// Emacs style mode select	 -*- C++ -*- 
//-----------------------------------------------------------------------------
//
// $Id:$
//
// Copyright (C) 1993-1996 by id Software, Inc.
//
// This source is available for distribution and/or modification
// only under the terms of the DOOM Source Code License as
// published by id Software. All rights reserved.
//
// The source is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
// for more details.
//
// $Log:$
//
// DESCRIPTION:
//		Movement, collision handling.
//		Shooting and aiming.
//
//-----------------------------------------------------------------------------

#include <stdlib.h>
#include <math.h>

#include "templates.h"

#include "m_bbox.h"
#include "m_random.h"
#include "i_system.h"
#include "c_dispatch.h"

#include "doomdef.h"
#include "p_local.h"
#include "p_lnspec.h"
#include "p_effect.h"
#include "p_terrain.h"
#include "p_trace.h"

#include "s_sound.h"
#include "decallib.h"

// State.
#include "doomstat.h"
#include "r_state.h"

#include "gi.h"

#include "a_sharedglobal.h"
#include "p_conversation.h"
#include "r_translate.h"
#include "g_level.h"

#define WATER_SINK_FACTOR		3
#define WATER_SINK_SMALL_FACTOR	4
#define WATER_SINK_SPEED		(FRACUNIT/2)
#define WATER_JUMP_SPEED		(FRACUNIT*7/2)

CVAR (Bool, cl_bloodsplats, true, CVAR_ARCHIVE)
CVAR (Int, sv_smartaim, 0, CVAR_ARCHIVE|CVAR_SERVERINFO)

static void CheckForPushSpecial (line_t *line, int side, AActor *mobj);
static void SpawnShootDecal (AActor *t1, const FTraceResults &trace);
static void SpawnDeepSplash (AActor *t1, const FTraceResults &trace, AActor *puff,
							 fixed_t vx, fixed_t vy, fixed_t vz, fixed_t shootz);

static FRandom pr_tracebleed ("TraceBleed");
static FRandom pr_checkthing ("CheckThing");
static FRandom pr_lineattack ("LineAttack");
static FRandom pr_crunch ("DoCrunch");

// keep track of special lines as they are hit,
// but don't process them until the move is proven valid
TArray<line_t *> spechit;

// Temporary holder for thing_sectorlist threads
msecnode_t* sector_list = NULL;		// phares 3/16/98

//==========================================================================
//
// PIT_FindFloorCeiling
//
//==========================================================================

static bool PIT_FindFloorCeiling (line_t *ld, const FBoundingBox &box, FCheckPosition &tmf)
{
	if (box.Right() <= ld->bbox[BOXLEFT]
		|| box.Left() >= ld->bbox[BOXRIGHT]
		|| box.Top() <= ld->bbox[BOXBOTTOM]
		|| box.Bottom() >= ld->bbox[BOXTOP] )
		return true;

	if (box.BoxOnLineSide (ld) != -1)
		return true;

	// A line has been hit
	
	if (!ld->backsector)
	{ // One sided line
		return true;
	}

	fixed_t sx, sy;
	FLineOpening open;

	// set openrange, opentop, openbottom
	if ((((ld->frontsector->floorplane.a | ld->frontsector->floorplane.b) |
		 (ld->backsector->floorplane.a | ld->backsector->floorplane.b) |
		 (ld->frontsector->ceilingplane.a | ld->frontsector->ceilingplane.b) |
		 (ld->backsector->ceilingplane.a | ld->backsector->ceilingplane.b)) == 0)
		 && ld->backsector->e->XFloor.ffloors.Size()==0 && ld->frontsector->e->XFloor.ffloors.Size()==0)
	{
		P_LineOpening (open, tmf.thing, ld, sx=tmf.x, sy=tmf.y, tmf.x, tmf.y);
	}
	else
	{ // Find the point on the line closest to the actor's center, and use
	  // that to calculate openings
		float dx = (float)ld->dx;
		float dy = (float)ld->dy;
		fixed_t r = (fixed_t)(((float)(tmf.x - ld->v1->x) * dx +
				 			   (float)(tmf.y - ld->v1->y) * dy) /
							  (dx*dx + dy*dy) * 16777216.f);
		if (r <= 0)
		{
			P_LineOpening (open, tmf.thing, ld, sx=ld->v1->x, sy=ld->v1->y, tmf.x, tmf.y);
		}
		else if (r >= (1<<24))
		{
			P_LineOpening (open, tmf.thing, ld, sx=ld->v2->x, sy=ld->v2->y, tmf.thing->x, tmf.thing->y);
		}
		else
		{
			P_LineOpening (open, tmf.thing, ld, sx=ld->v1->x + MulScale24 (r, ld->dx),
				sy=ld->v1->y + MulScale24 (r, ld->dy), tmf.x, tmf.y);
		}
	}

	// adjust floor / ceiling heights
	if (open.top < tmf.ceilingz)
	{
		tmf.ceilingz = open.top;
	}

	if (open.bottom > tmf.floorz)
	{
		tmf.floorz = open.bottom;
		tmf.floorsector = open.bottomsec;
		tmf.touchmidtex = open.touchmidtex;
	}
	else if (open.bottom == tmf.floorz)
	{
		tmf.touchmidtex |= open.touchmidtex;
	}

	if (open.lowfloor < tmf.dropoffz)
		tmf.dropoffz = open.lowfloor;
	
	return true;
}


void P_GetFloorCeilingZ(FCheckPosition &tmf, bool get)
{
	sector_t *sec;
	if (get)
	{
		sec = P_PointInSector (tmf.x, tmf.y);
		tmf.floorsector = sec;
		tmf.ceilingsector = sec;

		tmf.floorz = tmf.dropoffz = sec->floorplane.ZatPoint (tmf.x, tmf.y);
		tmf.ceilingz = sec->ceilingplane.ZatPoint (tmf.x, tmf.y);
		tmf.floorpic = sec->GetTexture(sector_t::floor);
		tmf.ceilingpic = sec->GetTexture(sector_t::ceiling);
	}
	else sec = tmf.thing->Sector;

#ifdef _3DFLOORS
	for(unsigned int i=0;i<sec->e->XFloor.ffloors.Size();i++)
	{
		F3DFloor*  rover = sec->e->XFloor.ffloors[i];

		if (!(rover->flags & FF_SOLID) || !(rover->flags & FF_EXISTS)) continue;

		fixed_t ff_bottom = rover->bottom.plane->ZatPoint(tmf.x, tmf.y);
		fixed_t ff_top = rover->top.plane->ZatPoint(tmf.x, tmf.y);

		if (ff_top > tmf.floorz)
		{
			if (ff_top < tmf.z || (tmf.thing != NULL && ff_bottom < tmf.z && ff_top < tmf.z + tmf.thing->MaxStepHeight))  
			{
				tmf.dropoffz = tmf.floorz = ff_top;
				tmf.floorpic = *rover->top.texture;
			}
		}
		if (ff_bottom < tmf.ceilingz && ff_bottom > tmf.z + tmf.thing->height) 
		{
			tmf.ceilingz = ff_bottom;
			tmf.ceilingpic = *rover->bottom.texture;
		}
	}
#endif
}

//==========================================================================
//
// P_FindFloorCeiling
//
//==========================================================================

void P_FindFloorCeiling (AActor *actor, bool onlyspawnpos)
{
	FCheckPosition tmf;

	tmf.thing = actor;
	tmf.x = actor->x;
	tmf.y = actor->y;
	tmf.z = actor->z;

	if (!onlyspawnpos)
	{
		P_GetFloorCeilingZ(tmf, true);
	}
	else
	{
		tmf.ceilingsector = tmf.floorsector = actor->Sector;

		tmf.floorz = tmf.dropoffz = actor->floorz;
		tmf.ceilingz = actor->ceilingz;
		tmf.floorpic = actor->floorpic;
		tmf.ceilingpic = actor->ceilingpic;
		P_GetFloorCeilingZ(tmf, false);
	}
	actor->floorz = tmf.floorz;
	actor->dropoffz = tmf.dropoffz;
	actor->ceilingz = tmf.ceilingz;
	actor->floorpic = tmf.floorpic;
	actor->floorsector = tmf.floorsector;
	actor->ceilingpic = tmf.ceilingpic;
	actor->ceilingsector = tmf.ceilingsector;

	FBoundingBox box(tmf.x, tmf.y, actor->radius);

	tmf.touchmidtex = false;
	validcount++;

	FBlockLinesIterator it(box);
	line_t *ld;

	while ((ld = it.Next()))
	{
		PIT_FindFloorCeiling(ld, box, tmf);
	}

	if (tmf.touchmidtex) tmf.dropoffz = tmf.floorz;

	if (!onlyspawnpos || (tmf.touchmidtex && (tmf.floorz <= actor->z)))
	{
		actor->floorz = tmf.floorz;
		actor->dropoffz = tmf.dropoffz;
		actor->ceilingz = tmf.ceilingz;
		actor->floorpic = tmf.floorpic;
		actor->floorsector = tmf.floorsector;
		actor->ceilingpic = tmf.ceilingpic;
		actor->ceilingsector = tmf.ceilingsector;
	}
	else
	{
		actor->floorsector = actor->ceilingsector = actor->Sector;
		// [BB] Don't forget to update floorpic and ceilingpic.
		if (actor->Sector != NULL)
		{
			actor->floorpic = actor->Sector->GetTexture(sector_t::floor);
			actor->ceilingpic = actor->Sector->GetTexture(sector_t::ceiling);
		}
	}
}

//
// TELEPORT MOVE
// 

//
// P_TeleportMove
//
// [RH] Added telefrag parameter: When true, anything in the spawn spot
//		will always be telefragged, and the move will be successful.
//		Added z parameter. Originally, the thing's z was set *after* the
//		move was made, so the height checking I added for 1.13 could
//		potentially erroneously indicate the move was okay if the thing
//		was being teleported between two non-overlapping height ranges.
bool P_TeleportMove (AActor *thing, fixed_t x, fixed_t y, fixed_t z, bool telefrag)
{
	FCheckPosition tmf;
	
	// kill anything occupying the position
		
	
	// The base floor/ceiling is from the subsector that contains the point.
	// Any contacted lines the step closer together will adjust them.
	tmf.thing = thing;
	tmf.x = x;
	tmf.y = y;
	tmf.z = z;
	P_GetFloorCeilingZ(tmf, true);
					
	spechit.Clear ();

	bool StompAlwaysFrags = (thing->flags2 & MF2_TELESTOMP) || 
							(level.flags & LEVEL_MONSTERSTELEFRAG) || telefrag;

	FBoundingBox box(x, y, thing->radius);
	FBlockLinesIterator it(box);
	line_t *ld;

	while ((ld = it.Next()))
	{
		PIT_FindFloorCeiling(ld, box, tmf);
	}

	if (tmf.touchmidtex) tmf.dropoffz = tmf.floorz;

	FBlockThingsIterator it2(FBoundingBox(x, y, thing->radius));
	AActor *th;

	while ((th = it2.Next()))
	{
		if (!(th->flags & MF_SHOOTABLE))
			continue;

		// don't clip against self
		if (th == thing)
			continue;

		fixed_t blockdist = th->radius + tmf.thing->radius;
		if ( abs(th->x - tmf.x) >= blockdist || abs(th->y - tmf.y) >= blockdist)
			continue;

		// [RH] Z-Check
		// But not if not MF2_PASSMOBJ or MF3_DONTOVERLAP are set!
		// Otherwise those things would get stuck inside each other.
		if ((thing->flags2 & MF2_PASSMOBJ || th->flags4 & MF4_ACTLIKEBRIDGE) && !(i_compatflags & COMPATF_NO_PASSMOBJ))
		{
			if (!(th->flags3 & thing->flags3 & MF3_DONTOVERLAP))
			{
				if (z > th->z + th->height ||	// overhead
					z+thing->height < th->z)	// underneath
					continue;
			}
		}

		// monsters don't stomp things except on boss level
		// [RH] Some Heretic/Hexen monsters can telestomp
		if (StompAlwaysFrags && !(th->flags6 & MF6_NOTELEFRAG))
		{
			P_DamageMobj (th, thing, thing, TELEFRAG_DAMAGE, NAME_Telefrag, DMG_THRUSTLESS);
			continue;
		}
		return false;
	}
	
	// the move is ok, so link the thing into its new position
	thing->SetOrigin (x, y, z);
	thing->floorz = tmf.floorz;
	thing->ceilingz = tmf.ceilingz;
	thing->floorsector = tmf.floorsector;
	thing->floorpic = tmf.floorpic;
	thing->ceilingsector = tmf.ceilingsector;
	thing->ceilingpic = tmf.ceilingpic;
	thing->dropoffz = tmf.dropoffz;        // killough 11/98
	thing->BlockingLine = NULL;

	if (thing->flags2 & MF2_FLOORCLIP)
	{
		thing->AdjustFloorClip ();
	}

	if (thing == players[consoleplayer].camera)
	{
		R_ResetViewInterpolation ();
	}

	thing->PrevX = x;
	thing->PrevY = y;
	thing->PrevZ = z;

	return true;
}

//
// [RH] P_PlayerStartStomp
//
// Like P_TeleportMove, but it doesn't move anything, and only monsters and other
// players get telefragged.
//
void P_PlayerStartStomp (AActor *actor)
{
	AActor *th;
	FBlockThingsIterator it(FBoundingBox(actor->x, actor->y, actor->radius));

	while ((th = it.Next()))
	{
		if (!(th->flags & MF_SHOOTABLE))
			continue;

		// don't clip against self, and don't kill your own voodoo dolls
		if (th == actor || (th->player == actor->player && th->player != NULL))
			continue;

		if (!th->intersects(actor))
			continue;

		// only kill monsters and other players
		if (th->player == NULL && !(th->flags3 & MF3_ISMONSTER))
			continue;

		if (actor->z > th->z + th->height)
			continue;        // overhead
		if (actor->z + actor->height < th->z)
			continue;        // underneath

		P_DamageMobj (th, actor, actor, TELEFRAG_DAMAGE, NAME_Telefrag);
	}
}

inline fixed_t secfriction (const sector_t *sec)
{
	fixed_t friction = Terrains[TerrainTypes[sec->GetTexture(sector_t::floor)]].Friction;
	return friction != 0 ? friction : sec->friction;
}

inline fixed_t secmovefac (const sector_t *sec)
{
	fixed_t movefactor = Terrains[TerrainTypes[sec->GetTexture(sector_t::floor)]].MoveFactor;
	return movefactor != 0 ? movefactor : sec->movefactor;
}

//
// killough 8/28/98:
//
// P_GetFriction()
//
// Returns the friction associated with a particular mobj.

int P_GetFriction (const AActor *mo, int *frictionfactor)
{
	int friction = ORIG_FRICTION;
	int movefactor = ORIG_FRICTION_FACTOR;
	const msecnode_t *m;
	const sector_t *sec;

	if (mo->flags2 & MF2_FLY && mo->flags & MF_NOGRAVITY)
	{
		friction = FRICTION_FLY;
	}
	else if ((!(mo->flags & MF_NOGRAVITY) && mo->waterlevel > 1) ||
		(mo->waterlevel == 1 && mo->z > mo->floorz + 6*FRACUNIT))
	{
		friction = secfriction (mo->Sector);
		movefactor = secmovefac (mo->Sector) >> 1;
	}
	else if (var_friction && !(mo->flags & (MF_NOCLIP|MF_NOGRAVITY)))
	{	// When the object is straddling sectors with the same
		// floor height that have different frictions, use the lowest
		// friction value (muddy has precedence over icy).

		for (m = mo->touching_sectorlist; m; m = m->m_tnext)
		{
			sec = m->m_sector;

#ifdef _3DFLOORS
			// 3D floors must be checked, too
			for(unsigned i=0;i<sec->e->XFloor.ffloors.Size();i++)
			{
				F3DFloor * rover=sec->e->XFloor.ffloors[i];
				if (!(rover->flags&FF_EXISTS)) continue;
				if(!(rover->flags & FF_SOLID)) continue;

				// Player must be on top of the floor to be affected...
				if(mo->z != rover->top.plane->ZatPoint(mo->x,mo->y)) continue;
				fixed_t newfriction=secfriction(rover->model);
				if (newfriction<friction)
				{
					friction = newfriction;
					movefactor = secmovefac(rover->model);
				}
			}
#endif

			if (!(sec->special & FRICTION_MASK) &&
				Terrains[TerrainTypes[sec->GetTexture(sector_t::floor)]].Friction == 0)
			{
				continue;
			}
			if ((secfriction(sec) < friction || friction == ORIG_FRICTION) &&
				(mo->z <= sec->floorplane.ZatPoint (mo->x, mo->y) ||
				(sec->GetHeightSec() != NULL &&
				 mo->z <= sec->heightsec->floorplane.ZatPoint (mo->x, mo->y))))
			{
				friction = secfriction (sec);
				movefactor = secmovefac (sec);
			}
		}
	}
  
	if (frictionfactor)
		*frictionfactor = movefactor;

	return friction;
}

// phares 3/19/98
// P_GetMoveFactor() returns the value by which the x,y
// movements are multiplied to add to player movement.
//
// killough 8/28/98: rewritten

int P_GetMoveFactor (const AActor *mo, int *frictionp)
{
	int movefactor, friction;

	// If the floor is icy or muddy, it's harder to get moving. This is where
	// the different friction factors are applied to 'trying to move'. In
	// p_mobj.c, the friction factors are applied as you coast and slow down.

	if ((friction = P_GetFriction(mo, &movefactor)) < ORIG_FRICTION)
	{
		// phares 3/11/98: you start off slowly, then increase as
		// you get better footing

		int velocity = P_AproxDistance(mo->velx, mo->vely);

		if (velocity > MORE_FRICTION_VELOCITY<<2)
			movefactor <<= 3;
		else if (velocity > MORE_FRICTION_VELOCITY<<1)
			movefactor <<= 2;
		else if (velocity > MORE_FRICTION_VELOCITY)
			movefactor <<= 1;
	}

	if (frictionp)
		*frictionp = friction;

	return movefactor;
}

//
// MOVEMENT ITERATOR FUNCTIONS
//

//
// PIT_CheckLine
// Adjusts tmfloorz and tmceilingz as lines are contacted
//

static // killough 3/26/98: make static
bool PIT_CheckLine (line_t *ld, const FBoundingBox &box, FCheckPosition &tm)
{
	bool rail = false;

	if (box.Right() <= ld->bbox[BOXLEFT]
		|| box.Left() >= ld->bbox[BOXRIGHT]
		|| box.Top() <= ld->bbox[BOXBOTTOM]
		|| box.Bottom() >= ld->bbox[BOXTOP] )
		return true;

	if (box.BoxOnLineSide (ld) != -1)
		return true;

	// A line has been hit
/*
=
= The moving thing's destination position will cross the given line.
= If this should not be allowed, return false.
= If the line is special, keep track of it to process later if the move
=       is proven ok.  NOTE: specials are NOT sorted by order, so two special lines
=       that are only 8 pixels apart could be crossed in either order.
*/
	
	if (!ld->backsector)
	{ // One sided line
		if (tm.thing->flags2 & MF2_BLASTED)
		{
			P_DamageMobj (tm.thing, NULL, NULL, tm.thing->Mass >> 5, NAME_Melee);
		}
		tm.thing->BlockingLine = ld;
		CheckForPushSpecial (ld, 0, tm.thing);
		return false;
	}

		// MBF bouncers are treated as missiles here.
		bool Projectile = (tm.thing->flags & MF_MISSILE || tm.thing->BounceFlags & BOUNCE_MBF);
		// MBF considers that friendly monsters are not blocked by monster-blocking lines.
		// This is added here as a compatibility option. Note that monsters that are dehacked
		// into being friendly with the MBF flag automatically gain MF3_NOBLOCKMONST, so this
		// just optionally generalizes the behavior to other friendly monsters.
		bool NotBlocked = ((tm.thing->flags3 & MF3_NOBLOCKMONST)
			|| ((i_compatflags & COMPATF_NOBLOCKFRIENDS) && (tm.thing->flags & MF_FRIENDLY)));

		if (!(Projectile) || (ld->flags & (ML_BLOCKEVERYTHING|ML_BLOCKPROJECTILE)))	{
		if (ld->flags & ML_RAILING)
		{
			rail = true;
		}
		else if ((ld->flags & (ML_BLOCKING|ML_BLOCKEVERYTHING)) || 				// explicitly blocking everything
			(!(NotBlocked) && (ld->flags & ML_BLOCKMONSTERS)) || 				// block monsters only
			(tm.thing->player != NULL && (ld->flags & ML_BLOCK_PLAYERS)) ||		// block players
			((Projectile) && (ld->flags & ML_BLOCKPROJECTILE)) ||				// block projectiles
			((tm.thing->flags & MF_FLOAT) && (ld->flags & ML_BLOCK_FLOATERS)))	// block floaters
		{
			if (tm.thing->flags2 & MF2_BLASTED)
			{
				P_DamageMobj (tm.thing, NULL, NULL, tm.thing->Mass >> 5, NAME_Melee);
			}
			tm.thing->BlockingLine = ld;
			CheckForPushSpecial (ld, 0, tm.thing);
			return false;
		}
	}

	// [RH] Steep sectors count as dropoffs (unless already in one)
	if (!(tm.thing->flags & MF_DROPOFF) &&
		!(tm.thing->flags & (MF_NOGRAVITY|MF_NOCLIP)))
	{
		if (ld->frontsector->floorplane.c < STEEPSLOPE ||
			ld->backsector->floorplane.c < STEEPSLOPE)
		{
			const msecnode_t *node = tm.thing->touching_sectorlist;
			bool allow = false;
			int count = 0;
			while (node != NULL)
			{
				count++;
				if (node->m_sector->floorplane.c < STEEPSLOPE)
				{
					allow = true;
					break;
				}
				node = node->m_tnext;
			}
			if (!allow)
			{
				return false;
			}
		}
	}

	fixed_t sx=0, sy=0;
	FLineOpening open;

	// set openrange, opentop, openbottom
	if ((((ld->frontsector->floorplane.a | ld->frontsector->floorplane.b) |
		 (ld->backsector->floorplane.a | ld->backsector->floorplane.b) |
		 (ld->frontsector->ceilingplane.a | ld->frontsector->ceilingplane.b) |
		 (ld->backsector->ceilingplane.a | ld->backsector->ceilingplane.b)) == 0)
		 && ld->backsector->e->XFloor.ffloors.Size()==0 && ld->frontsector->e->XFloor.ffloors.Size()==0)
	{
		P_LineOpening (open, tm.thing, ld, sx=tm.x, sy=tm.y, tm.x, tm.y);
	}
	else
	{ // Find the point on the line closest to the actor's center, and use
	  // that to calculate openings
		float dx = (float)ld->dx;
		float dy = (float)ld->dy;
		fixed_t r = (fixed_t)(((float)(tm.x - ld->v1->x) * dx +
				 			   (float)(tm.y - ld->v1->y) * dy) /
							  (dx*dx + dy*dy) * 16777216.f);
/*		Printf ("%d:%d: %d  (%d %d %d %d)  (%d %d %d %d)\n", level.time, ld-lines, r,
			ld->frontsector->floorplane.a,
			ld->frontsector->floorplane.b,
			ld->frontsector->floorplane.c,
			ld->frontsector->floorplane.ic,
			ld->backsector->floorplane.a,
			ld->backsector->floorplane.b,
			ld->backsector->floorplane.c,
			ld->backsector->floorplane.ic);*/
		if (r <= 0)
		{
			P_LineOpening (open, tm.thing, ld, sx=ld->v1->x, sy=ld->v1->y, tm.x, tm.y);
		}
		else if (r >= (1<<24))
		{
			P_LineOpening (open, tm.thing, ld, sx=ld->v2->x, sy=ld->v2->y, tm.thing->x, tm.thing->y);
		}
		else
		{
			P_LineOpening (open, tm.thing, ld, sx=ld->v1->x + MulScale24 (r, ld->dx),
				sy=ld->v1->y + MulScale24 (r, ld->dy), tm.x, tm.y);
		}

		// the floorplane on both sides is identical with the current one
		// so don't mess around with the z-position
		if (ld->frontsector->floorplane==ld->backsector->floorplane &&
			ld->frontsector->floorplane==tm.thing->Sector->floorplane &&
			!ld->frontsector->e->XFloor.ffloors.Size() && !ld->backsector->e->XFloor.ffloors.Size())
		{
			open.bottom=INT_MIN;
		}
		/*	Printf ("    %d %d %d\n", sx, sy, openbottom);*/
	}

	if (rail &&
		// Eww! Gross! This check means the rail only exists if you stand on the
		// high side of the rail. So if you're walking on the low side of the rail,
		// it's possible to get stuck in the rail until you jump out. Unfortunately,
		// there is an area on Strife MAP04 that requires this behavior. Still, it's
		// better than Strife's handling of rails, which lets you jump into rails
		// from either side. How long until somebody reports this as a bug and I'm
		// forced to say, "It's not a bug. It's a feature?" Ugh.
		(!(level.flags2 & LEVEL2_RAILINGHACK) ||
		 open.bottom == tm.thing->Sector->floorplane.ZatPoint (sx, sy)))
	{
		open.bottom += 32*FRACUNIT;
	}

	// adjust floor / ceiling heights
	if (open.top < tm.ceilingz)
	{
		tm.ceilingz = open.top;
		tm.ceilingsector = open.topsec;
		tm.ceilingpic = open.ceilingpic;
		tm.ceilingline = ld;
		tm.thing->BlockingLine = ld;
	}

	if (open.bottom > tm.floorz)
	{
		tm.floorz = open.bottom;
		tm.floorsector = open.bottomsec;
		tm.floorpic = open.floorpic;
		tm.touchmidtex = open.touchmidtex;
		tm.thing->BlockingLine = ld;
	}
	else if (open.bottom == tm.floorz)
	{
		tm.touchmidtex |= open.touchmidtex;
	}

	if (open.lowfloor < tm.dropoffz)
		tm.dropoffz = open.lowfloor;
	
	// if contacted a special line, add it to the list
	if (ld->special)
	{
		spechit.Push (ld);
	}

	return true;
}

//==========================================================================
//
// PIT_CheckThing
//
//==========================================================================

bool PIT_CheckThing (AActor *thing, FCheckPosition &tm)
{
	fixed_t topz;
	bool 	solid;
	int 	damage;

	if (!((thing->flags & (MF_SOLID|MF_SPECIAL|MF_SHOOTABLE)) || thing->flags6 & MF6_TOUCHY))
		return true;	// can't hit thing

	fixed_t blockdist = thing->radius + tm.thing->radius;
	if ( abs(thing->x - tm.x) >= blockdist || abs(thing->y - tm.y) >= blockdist)
		return true;

	// don't clip against self
	if (thing == tm.thing)
		return true;

	if ((thing->flags2 | tm.thing->flags2) & MF2_THRUACTORS) 
		return true;

	if ((tm.thing->flags6 & MF6_THRUSPECIES) && (tm.thing->GetSpecies() == thing->GetSpecies()))
		return true;

	tm.thing->BlockingMobj = thing;
	topz = thing->z + thing->height;
	if (!(i_compatflags & COMPATF_NO_PASSMOBJ) && !(tm.thing->flags & (MF_FLOAT|MF_MISSILE|MF_SKULLFLY|MF_NOGRAVITY)) &&
		(thing->flags & MF_SOLID) && (thing->flags4 & MF4_ACTLIKEBRIDGE))
	{
		// [RH] Let monsters walk on actors as well as floors
		if ((tm.thing->flags3 & MF3_ISMONSTER) &&
			topz >= tm.floorz && topz <= tm.thing->z + tm.thing->MaxStepHeight)
		{
			// The commented-out if is an attempt to prevent monsters from walking off a
			// thing further than they would walk off a ledge. I can't think of an easy
			// way to do this, so I restrict them to only walking on bridges instead.
			// Uncommenting the if here makes it almost impossible for them to walk on
			// anything, bridge or otherwise.
//			if (abs(thing->x - tmx) <= thing->radius &&
//				abs(thing->y - tmy) <= thing->radius)
			{
				tm.stepthing = thing;
				tm.floorz = topz;
			}
		}
	}
	// [RH] If the other thing is a bridge, then treat the moving thing as if it had MF2_PASSMOBJ, so
	// you can use a scrolling floor to move scenery items underneath a bridge.
	if ((tm.thing->flags2 & MF2_PASSMOBJ || thing->flags4 & MF4_ACTLIKEBRIDGE) && !(i_compatflags & COMPATF_NO_PASSMOBJ))
	{ // check if a mobj passed over/under another object
		if (tm.thing->flags3 & thing->flags3 & MF3_DONTOVERLAP)
		{ // Some things prefer not to overlap each other, if possible
			return false;
		}
		if ((tm.thing->z >= topz) || (tm.thing->z + tm.thing->height <= thing->z))
		{
			return true;
		}
	}

	// touchy object is alive, toucher is solid
	if (thing->flags6 & MF6_TOUCHY && tm.thing->flags & MF_SOLID && thing->health > 0 &&
	// Thing is an armed mine or a sentient thing
	(thing->flags6 & MF6_ARMED || thing->IsSentient()) &&
	// either different classes or players
		(thing->player || thing->GetClass() != tm.thing->GetClass()) &&
	// or different species if DONTHARMSPECIES
		(!(thing->flags6 & MF6_DONTHARMSPECIES) || thing->GetSpecies() != tm.thing->GetSpecies()) &&
	// touches vertically
		thing->z + thing->height >= tm.thing->z && tm.thing->z + tm.thing->height >= thing->z &&
	// prevents lost souls from exploding when fired by pain elementals
		(thing->master != tm.thing && tm.thing->master != thing))
	// Difference with MBF: MBF hardcodes the LS/PE check and lets actors of the same species
	// but different classes trigger the touchiness, but that seems less straightforwards.
	{
		thing->flags6 &= ~MF6_ARMED; // Disarm
		P_DamageMobj (thing, NULL, NULL, thing->health, NAME_None, DMG_FORCED);  // kill object
		return true;
	}

	// Check for MF6_BUMPSPECIAL
	// By default, only players can activate things by bumping into them
	if ((thing->flags6 & MF6_BUMPSPECIAL))
	{
		if (((tm.thing->player != NULL)
		|| ((thing->activationtype & THINGSPEC_MonsterTrigger) && (thing->flags3 & MF3_ISMONSTER))
		|| ((thing->activationtype & THINGSPEC_MissileTrigger) && (thing->flags & MF_MISSILE))
		))
		{	// Target switching mechanism
			if (thing->activationtype & THINGSPEC_ThingTargets) thing->target = tm.thing;
			if (thing->activationtype & THINGSPEC_TriggerTargets) tm.thing->target = thing;
			// Run the special
			
			int res = LineSpecials[thing->special] (NULL, 
				((thing->activationtype & THINGSPEC_ThingActs) ? thing : tm.thing), // Who triggers?
				false, thing->args[0], thing->args[1], thing->args[2], thing->args[3], thing->args[4]);

			if (thing->activationtype & THINGSPEC_ClearSpecial && res) thing->special = 0;

		}
	}

	// Check for skulls slamming into things
	if (tm.thing->flags & MF_SKULLFLY)
	{
		bool res = tm.thing->Slam (tm.thing->BlockingMobj);
		tm.thing->BlockingMobj = NULL;
		return res;
	}
	// Check for blasted thing running into another
	if ((tm.thing->flags2 & MF2_BLASTED) && (thing->flags & MF_SHOOTABLE))
	{
		if (!(thing->flags2 & MF2_BOSS) && (thing->flags3 & MF3_ISMONSTER))
		{
			thing->velx += tm.thing->velx;
			thing->vely += tm.thing->vely;
			if ((thing->velx + thing->vely) > 3*FRACUNIT)
			{
				damage = (tm.thing->Mass / 100) + 1;
				P_DamageMobj (thing, tm.thing, tm.thing, damage, tm.thing->DamageType);
				P_TraceBleed (damage, thing, tm.thing);
				damage = (thing->Mass / 100) + 1;
				P_DamageMobj (tm.thing, thing, thing, damage >> 2, tm.thing->DamageType);
				P_TraceBleed (damage, tm.thing, thing);
			}
			return false;
		}
	}
	// Check for missile or non-solid MBF bouncer
	if (tm.thing->flags & MF_MISSILE || ((tm.thing->BounceFlags & BOUNCE_MBF) && !(tm.thing->flags & MF_SOLID)))
	{
		// Check for a non-shootable mobj
		if (thing->flags2 & MF2_NONSHOOTABLE)
		{
			return true;
		}
		// Check for passing through a ghost
		if ((thing->flags3 & MF3_GHOST) && (tm.thing->flags2 & MF2_THRUGHOST))
		{
			return true;
		}

		if ((tm.thing->flags6 & MF6_MTHRUSPECIES) 
			&& tm.thing->target // NULL pointer check
			&& (tm.thing->target->GetSpecies() == thing->GetSpecies()))
			return true;

		// Check for rippers passing through corpses
		if ((thing->flags & MF_CORPSE) && (tm.thing->flags2 & MF2_RIP) && !(thing->flags & MF_SHOOTABLE))
		{
			return true;
		}

		int clipheight;
		
		if (thing->projectilepassheight > 0) 
		{
			clipheight = thing->projectilepassheight;
		}
		else if (thing->projectilepassheight < 0 && (i_compatflags & COMPATF_MISSILECLIP))
		{
			clipheight = -thing->projectilepassheight;
		}
		else
		{
			clipheight = thing->height;
		}

		// Check if it went over / under
		if (tm.thing->z > thing->z + clipheight)
		{ // Over thing
			return true;
		}
		if (tm.thing->z+tm.thing->height < thing->z)
		{ // Under thing
			return true;
		}

		// [RH] What is the point of this check, again? In Hexen, it is unconditional,
		// but here we only do it if the missile's damage is 0.
		// MBF bouncer might have a non-0 damage value, but they must not deal damage on impact either.
		if ((tm.thing->BounceFlags & BOUNCE_Actors) && (tm.thing->Damage == 0 || !(tm.thing->flags & MF_MISSILE)))
		{
			return (tm.thing->target == thing || !(thing->flags & MF_SOLID));
		}

		switch (tm.thing->SpecialMissileHit (thing))
		{
		case 0:		return false;
		case 1:		return true;
		default:	break;
		}

		// [RH] Extend DeHacked infighting to allow for monsters
		// to never fight each other

		// [Graf Zahl] Why do I have the feeling that this didn't really work anymore now
		// that ZDoom supports friendly monsters?
		

		if (tm.thing->target != NULL)
		{
			if (thing == tm.thing->target)
			{ // Don't missile self
				return true;
			}

			// players are never subject to infighting settings and are always allowed
			// to harm / be harmed by anything.
			if (!thing->player && !tm.thing->target->player)
			{
				int infight;
				if (level.flags2 & LEVEL2_TOTALINFIGHTING) infight=1;
				else if (level.flags2 & LEVEL2_NOINFIGHTING) infight=-1;
				else infight = infighting;
				
				if (infight < 0)
				{
					// -1: Monsters cannot hurt each other, but make exceptions for
					//     friendliness and hate status.
					if (tm.thing->target->flags & MF_SHOOTABLE)
					{
						if (!(thing->flags3 & MF3_ISMONSTER))
						{
							return false;	// Question: Should monsters be allowed to shoot barrels in this mode?
											// The old code does not.
						}

						// Monsters that are clearly hostile can always hurt each other
						if (!thing->IsHostile (tm.thing->target))
						{
							// The same if the shooter hates the target
							if (thing->tid == 0 || tm.thing->target->TIDtoHate != thing->tid)
							{
								return false;
							}
						}
					}
				}
				else if (infight == 0)
				{
					//  0: Monsters cannot hurt same species except 
					//     cases where they are clearly supposed to do that
					if (thing->IsFriend (tm.thing->target))
					{
						// Friends never harm each other
						return false;
					}
					if (thing->TIDtoHate != 0 && thing->TIDtoHate == tm.thing->target->TIDtoHate)
					{
						// [RH] Don't hurt monsters that hate the same thing as you do
						return false;
					}
					if (thing->GetSpecies() == tm.thing->target->GetSpecies())
					{
						// Don't hurt same species or any relative -
						// but only if the target isn't one's hostile.
						if (!thing->IsHostile (tm.thing->target))
						{
							// Allow hurting monsters the shooter hates.
							if (thing->tid == 0 || tm.thing->target->TIDtoHate != thing->tid)
							{
								return false;
							}
						}
					}
				}
				// else if (infight==1) any shot hurts anything - no further tests
			}
		}
		if (!(thing->flags & MF_SHOOTABLE))
		{ // Didn't do any damage
			return !(thing->flags & MF_SOLID);
		}
		if ((thing->flags4 & MF4_SPECTRAL) && !(tm.thing->flags4 & MF4_SPECTRAL))
		{
			return true;
		}
		if (tm.DoRipping && !(thing->flags5 & MF5_DONTRIP))
		{
			if (!(tm.thing->flags6 & MF6_NOBOSSRIP) || !(thing->flags2 & MF2_BOSS))
			{
				if (tm.LastRipped != thing)
				{
					tm.LastRipped = thing;
					if (!(thing->flags & MF_NOBLOOD) &&
						!(thing->flags2 & MF2_REFLECTIVE) &&
						!(tm.thing->flags3 & MF3_BLOODLESSIMPACT) &&
						!(thing->flags2 & (MF2_INVULNERABLE|MF2_DORMANT)))
					{ // Ok to spawn blood
						P_RipperBlood (tm.thing, thing);
					}
					S_Sound (tm.thing, CHAN_BODY, "misc/ripslop", 1, ATTN_IDLE);
					damage = tm.thing->GetMissileDamage (3, 2);
					P_DamageMobj (thing, tm.thing, tm.thing->target, damage, tm.thing->DamageType);
					if (!(tm.thing->flags3 & MF3_BLOODLESSIMPACT))
					{
						P_TraceBleed (damage, thing, tm.thing);
					}
					if (thing->flags2 & MF2_PUSHABLE
						&& !(tm.thing->flags2 & MF2_CANNOTPUSH))
					{ // Push thing
						if (thing->lastpush != tm.PushTime)
						{
							thing->velx += FixedMul(tm.thing->velx, thing->pushfactor);
							thing->vely += FixedMul(tm.thing->vely, thing->pushfactor);
							thing->lastpush = tm.PushTime;
						}
					}
				}
				spechit.Clear ();
				return true;
			}
		}
		// Do damage
		damage = tm.thing->GetMissileDamage ((tm.thing->flags4 & MF4_STRIFEDAMAGE) ? 3 : 7, 1);
		// [GZ] If MF6_FORCEPAIN is set, we need to call P_DamageMobj even if damage is 0!
		if ((damage > 0) || (tm.thing->flags6 & MF6_FORCEPAIN)) 
		{
			P_DamageMobj (thing, tm.thing, tm.thing->target, damage, tm.thing->DamageType);
			if (damage > 0)
			{
				if ((tm.thing->flags5 & MF5_BLOODSPLATTER) &&
					!(thing->flags & MF_NOBLOOD) &&
					!(thing->flags2 & MF2_REFLECTIVE) &&
					!(thing->flags2 & (MF2_INVULNERABLE|MF2_DORMANT)) &&
					!(tm.thing->flags3 & MF3_BLOODLESSIMPACT) &&
					(pr_checkthing() < 192))
				{
					P_BloodSplatter (tm.thing->x, tm.thing->y, tm.thing->z, thing);
				}
				if (!(tm.thing->flags3 & MF3_BLOODLESSIMPACT))
				{
					P_TraceBleed (damage, thing, tm.thing);
				}
			}
		}
		else if (damage < 0)
		{
			P_GiveBody (thing, -damage);
		}
		return false;		// don't traverse any more
	}
	if (thing->flags2 & MF2_PUSHABLE && !(tm.thing->flags2 & MF2_CANNOTPUSH) &&
		(tm.thing->player == NULL || !(tm.thing->player->cheats & CF_PREDICTING)))
	{ // Push thing
		if (thing->lastpush != tm.PushTime)
		{
			thing->velx += FixedMul(tm.thing->velx, thing->pushfactor);
			thing->vely += FixedMul(tm.thing->vely, thing->pushfactor);
			thing->lastpush = tm.PushTime;
		}
	}
	solid = (thing->flags & MF_SOLID) &&
			!(thing->flags & MF_NOCLIP) &&
			(tm.thing->flags & MF_SOLID);
	// Check for special pickup
	if ((thing->flags & MF_SPECIAL) && (tm.thing->flags & MF_PICKUP)
		// [RH] The next condition is to compensate for the extra height
		// that gets added by P_CheckPosition() so that you cannot pick
		// up things that are above your true height.
		&& thing->z < tm.thing->z + tm.thing->height - tm.thing->MaxStepHeight)
	{ // Can be picked up by tmthing
		P_TouchSpecialThing (thing, tm.thing);	// can remove thing
	}

	// killough 3/16/98: Allow non-solid moving objects to move through solid
	// ones, by allowing the moving thing (tmthing) to move if it's non-solid,
	// despite another solid thing being in the way.
	// killough 4/11/98: Treat no-clipping things as not blocking

	return !solid;

	// return !(thing->flags & MF_SOLID);	// old code -- killough
}



/*
===============================================================================

						MOVEMENT CLIPPING

===============================================================================
*/

//----------------------------------------------------------------------------
//
// FUNC P_TestMobjLocation
//
// Returns true if the mobj is not blocked by anything at its current
// location, otherwise returns false.
//
//----------------------------------------------------------------------------

bool P_TestMobjLocation (AActor *mobj)
{
	int flags;

	flags = mobj->flags;
	mobj->flags &= ~MF_PICKUP;
	if (P_CheckPosition(mobj, mobj->x, mobj->y))
	{ // XY is ok, now check Z
		mobj->flags = flags;
		fixed_t z = mobj->z;
		if (mobj->flags2 & MF2_FLOATBOB)
		{
			z -= FloatBobOffsets[(mobj->FloatBobPhase + level.maptime - 1) & 63];
		}
		if ((z < mobj->floorz) || (z + mobj->height > mobj->ceilingz))
		{ // Bad Z
			return false;
		}
		return true;
	}
	mobj->flags = flags;
	return false;
}


//
// P_CheckPosition
// This is purely informative, nothing is modified
// (except things picked up and missile damage applied).
// 
// in:
//	a AActor (can be valid or invalid)
//	a position to be checked
//	 (doesn't need to be related to the AActor->x,y)
//
// during:
//	special things are touched if MF_PICKUP
//	early out on solid lines?
//
// out:
//	newsubsec
//	floorz
//	ceilingz
//	tmdropoffz = the lowest point contacted (monsters won't move to a dropoff)
//	speciallines[]
//	numspeciallines
//  AActor *BlockingMobj = pointer to thing that blocked position (NULL if not
//   blocked, or blocked by a line).
bool P_CheckPosition (AActor *thing, fixed_t x, fixed_t y, FCheckPosition &tm)
{
	sector_t *newsec;
	AActor *thingblocker;
	AActor *fakedblocker;
	fixed_t realheight = thing->height;

	tm.thing = thing;

	tm.x = x;
	tm.y = y;

	newsec = P_PointInSector (x,y);
	tm.ceilingline = thing->BlockingLine = NULL;
	
// The base floor / ceiling is from the subsector that contains the point.
// Any contacted lines the step closer together will adjust them.
	tm.floorz = tm.dropoffz = newsec->floorplane.ZatPoint (x, y);
	tm.ceilingz = newsec->ceilingplane.ZatPoint (x, y);
	tm.floorpic = newsec->GetTexture(sector_t::floor);
	tm.floorsector = newsec;
	tm.ceilingpic = newsec->GetTexture(sector_t::ceiling);
	tm.ceilingsector = newsec;
	tm.touchmidtex = false;

	//Added by MC: Fill the tmsector.
	tm.sector = newsec;
	
#ifdef _3DFLOORS
	//Check 3D floors
	if(newsec->e->XFloor.ffloors.Size())
	{
		F3DFloor*  rover;
		fixed_t    delta1;
		fixed_t    delta2;
		int        thingtop = thing->z + (thing->height==0? 1:thing->height);
		
		for(unsigned i=0;i<newsec->e->XFloor.ffloors.Size();i++)
		{
			rover = newsec->e->XFloor.ffloors[i];
			if(!(rover->flags & FF_SOLID) || !(rover->flags & FF_EXISTS)) continue;

			fixed_t ff_bottom=rover->bottom.plane->ZatPoint(x, y);
			fixed_t ff_top=rover->top.plane->ZatPoint(x, y);
			
			delta1 = thing->z - (ff_bottom + ((ff_top-ff_bottom)/2));
			delta2 = thingtop - (ff_bottom + ((ff_top-ff_bottom)/2));

			if(ff_top > tm.floorz && abs(delta1) < abs(delta2)) 
			{
				tm.floorz = tm.dropoffz = ff_top;
				tm.floorpic = *rover->top.texture;
			}
			if(ff_bottom < tm.ceilingz && abs(delta1) >= abs(delta2)) 
			{
				tm.ceilingz = ff_bottom;
				tm.ceilingpic = *rover->bottom.texture;
			}
		}
	}
#endif
	
	validcount++;
	spechit.Clear ();

	if ((thing->flags & MF_NOCLIP) && !(thing->flags & MF_SKULLFLY))
		return true;
	
	// Check things first, possibly picking things up.
	// The bounding box is extended by MAXRADIUS
	// because DActors are grouped into mapblocks
	// based on their origin point, and can overlap
	// into adjacent blocks by up to MAXRADIUS units.
	thing->BlockingMobj = NULL;
	thingblocker = NULL;
	fakedblocker = NULL;
	if (thing->player)
	{ // [RH] Fake taller height to catch stepping up into things.
		thing->height = realheight + thing->MaxStepHeight;
	}

	tm.stepthing = NULL;
	FBoundingBox box(x, y, thing->radius);

	{
		FBlockThingsIterator it2(box);
		AActor *th;
		while ((th = it2.Next()))
		{
			if (!PIT_CheckThing(th, tm))
			{ // [RH] If a thing can be stepped up on, we need to continue checking
			  // other things in the blocks and see if we hit something that is
			  // definitely blocking. Otherwise, we need to check the lines, or we
			  // could end up stuck inside a wall.
				AActor *BlockingMobj = thing->BlockingMobj;

				if (BlockingMobj == NULL || (i_compatflags & COMPATF_NO_PASSMOBJ))
				{ // Thing slammed into something; don't let it move now.
					thing->height = realheight;
					return false;
				}
				else if (!BlockingMobj->player && !(thing->flags & (MF_FLOAT|MF_MISSILE|MF_SKULLFLY)) &&
					BlockingMobj->z+BlockingMobj->height-thing->z <= thing->MaxStepHeight)
				{
					if (thingblocker == NULL ||
						BlockingMobj->z > thingblocker->z)
					{
						thingblocker = BlockingMobj;
					}
					thing->BlockingMobj = NULL;
				}
				else if (thing->player &&
					thing->z + thing->height - BlockingMobj->z <= thing->MaxStepHeight)
				{
					if (thingblocker)
					{ // There is something to step up on. Return this thing as
					  // the blocker so that we don't step up.
						thing->height = realheight;
						return false;
					}
					// Nothing is blocking us, but this actor potentially could
					// if there is something else to step on.
					fakedblocker = BlockingMobj;
					thing->BlockingMobj = NULL;
				}
				else
				{ // Definitely blocking
					thing->height = realheight;
					return false;
				}
			}
		}
	}

	// check lines

	// [RH] We need to increment validcount again, because a function above may
	// have already set some lines to equal the current validcount.
	//
	// Specifically, when DehackedPickup spawns a new item in its TryPickup()
	// function, that new actor will set the lines around it to match validcount
	// when it links itself into the world. If we just leave validcount alone,
	// that will give the player the freedom to walk through walls at will near
	// a pickup they cannot get, because their validcount will prevent them from
	// being considered for collision with the player.
	validcount++;

	thing->BlockingMobj = NULL;
	thing->height = realheight;
	if (thing->flags & MF_NOCLIP)
		return (thing->BlockingMobj = thingblocker) == NULL;

	FBlockLinesIterator it(box);
	line_t *ld;

	fixed_t thingdropoffz = tm.floorz;
	//bool onthing = (thingdropoffz != tmdropoffz);
	tm.floorz = tm.dropoffz;

	while ((ld = it.Next()))
	{
		if (!PIT_CheckLine(ld, box, tm))
			return false;
	}

	if (tm.ceilingz - tm.floorz < thing->height)
		return false;

	if (tm.touchmidtex)
	{
		tm.dropoffz = tm.floorz;
	}
	else if (tm.stepthing != NULL)
	{
		tm.dropoffz = thingdropoffz;
	}

	return (thing->BlockingMobj = thingblocker) == NULL;
}

bool P_CheckPosition (AActor *thing, fixed_t x, fixed_t y)
{
	FCheckPosition tm;
	return P_CheckPosition(thing, x, y, tm);
}

//=============================================================================
//
// P_CheckOnmobj(AActor *thing)
//
//				Checks if the new Z position is legal
//=============================================================================

AActor *P_CheckOnmobj (AActor *thing)
{
	fixed_t oldz;
	bool good;
	AActor *onmobj;

	oldz = thing->z;
	P_FakeZMovement (thing);
	good = P_TestMobjZ (thing, false, &onmobj);
	thing->z = oldz;

	return good ? NULL : onmobj;
}

//=============================================================================
//
// P_TestMobjZ
//
//=============================================================================

bool P_TestMobjZ (AActor *actor, bool quick, AActor **pOnmobj)
{
	AActor *onmobj = NULL;
	if (actor->flags & MF_NOCLIP)
	{
		if (pOnmobj) *pOnmobj = NULL;
		return true;
	}

	FBlockThingsIterator it(FBoundingBox(actor->x, actor->y, actor->radius));
	AActor *thing;

	while ((thing = it.Next()))
	{
		if (!thing->intersects(actor))
		{
			continue;
		}
		if ((actor->flags2 | thing->flags2) & MF2_THRUACTORS)
		{
			continue;
		}
		if ((actor->flags6 & MF6_THRUSPECIES) && (thing->GetSpecies() == actor->GetSpecies()))
		{
			continue;
		}
		if (!(thing->flags & MF_SOLID))
		{ // Can't hit thing
			continue;
		}
		if (thing->flags & (MF_SPECIAL|MF_NOCLIP|MF_CORPSE))
		{ // [RH] Corpses and specials and noclippers don't block moves
			continue;
		}
		if (!(thing->flags4 & MF4_ACTLIKEBRIDGE) && (actor->flags & MF_SPECIAL))
		{ // [RH] Only bridges block pickup items
			continue;
		}
		if (thing == actor)
		{ // Don't clip against self
			continue;
		}
		if (actor->z > thing->z+thing->height)
		{ // over thing
			continue;
		}
		else if (actor->z+actor->height <= thing->z)
		{ // under thing
			continue;
		}
		else if (!quick && onmobj != NULL && thing->z + thing->height < onmobj->z + onmobj->height)
		{ // something higher is in the way
			continue;
		}
		onmobj = thing;
		if (quick) break;
	}

	if (pOnmobj) *pOnmobj = onmobj;
	return onmobj == NULL;
}

//=============================================================================
//
// P_FakeZMovement
//
//				Fake the zmovement so that we can check if a move is legal
//=============================================================================

void P_FakeZMovement (AActor *mo)
{
//
// adjust height
//
	mo->z += mo->velz;
	if ((mo->flags&MF_FLOAT) && mo->target)
	{ // float down towards target if too close
		if (!(mo->flags & MF_SKULLFLY) && !(mo->flags & MF_INFLOAT))
		{
			fixed_t dist = P_AproxDistance (mo->x - mo->target->x, mo->y - mo->target->y);
			fixed_t delta = (mo->target->z + (mo->height>>1)) - mo->z;
			if (delta < 0 && dist < -(delta*3))
				mo->z -= mo->FloatSpeed;
			else if (delta > 0 && dist < (delta*3))
				mo->z += mo->FloatSpeed;
		}
	}
	if (mo->player && mo->flags&MF_NOGRAVITY && (mo->z > mo->floorz))
	{
		mo->z += finesine[(FINEANGLES/80*level.maptime)&FINEMASK]/8;
	}

//
// clip movement
//
	if (mo->z <= mo->floorz)
	{ // hit the floor
		mo->z = mo->floorz;
	}

	if (mo->z + mo->height > mo->ceilingz)
	{ // hit the ceiling
		mo->z = mo->ceilingz - mo->height;
	}
}

//===========================================================================
//
// CheckForPushSpecial
//
//===========================================================================

static void CheckForPushSpecial (line_t *line, int side, AActor *mobj)
{
	if (line->special)
	{
		if (mobj->flags2 & MF2_PUSHWALL)
		{
			P_ActivateLine (line, mobj, side, SPAC_Push);
		}
		else if (mobj->flags2 & MF2_IMPACT)
		{
			if ((level.flags2 & LEVEL2_MISSILESACTIVATEIMPACT) ||
				!(mobj->flags & MF_MISSILE) ||
				(mobj->target == NULL))
			{
				P_ActivateLine (line, mobj, side, SPAC_Impact);
			}
			else
			{
				P_ActivateLine (line, mobj->target, side, SPAC_Impact);
			}
		}	
	}
}

//
// P_TryMove
// Attempt to move to a new position,
// crossing special lines unless MF_TELEPORT is set.
//
bool P_TryMove (AActor *thing, fixed_t x, fixed_t y,
				int dropoff, // killough 3/15/98: allow dropoff as option
				const secplane_t *onfloor, // [RH] Let P_TryMove keep the thing on the floor
				FCheckPosition &tm)
{
	fixed_t 	oldx;
	fixed_t 	oldy;
	fixed_t		oldz;
	int 		side;
	int 		oldside;
	line_t* 	ld;
	sector_t*	oldsec = thing->Sector;	// [RH] for sector actions
	sector_t*	newsec;

	tm.floatok = false;
	oldz = thing->z;
	if (onfloor)
	{
		thing->z = onfloor->ZatPoint (x, y);
	}
	if (!P_CheckPosition (thing, x, y, tm))
	{
		AActor *BlockingMobj = thing->BlockingMobj;
		// Solid wall or thing
		if (!BlockingMobj || BlockingMobj->player || !thing->player)
		{
			goto pushline;
		}
		else
		{
			if (BlockingMobj->player || !thing->player)
			{
				goto pushline;
			}
			else if (BlockingMobj->z+BlockingMobj->height-thing->z 
				> thing->MaxStepHeight
				|| (BlockingMobj->Sector->ceilingplane.ZatPoint (x, y)
				- (BlockingMobj->z+BlockingMobj->height) < thing->height)
				|| (tm.ceilingz-(BlockingMobj->z+BlockingMobj->height) 
				< thing->height))
			{
				goto pushline;
			}
		}
		if (!(tm.thing->flags2 & MF2_PASSMOBJ) || (i_compatflags & COMPATF_NO_PASSMOBJ))
		{
			thing->z = oldz;
			return false;
		}
	}

	if (thing->flags3 & MF3_FLOORHUGGER)
	{
		thing->z = tm.floorz;
	}
	else if (thing->flags3 & MF3_CEILINGHUGGER)
	{
		thing->z = tm.ceilingz - thing->height;
	}

	if (onfloor && tm.floorsector == thing->floorsector)
	{
		thing->z = tm.floorz;
	}
	if (!(thing->flags & MF_NOCLIP))
	{
		if (tm.ceilingz - tm.floorz < thing->height)
		{
			goto pushline;		// doesn't fit
		}

		tm.floatok = true;
		
		if (!(thing->flags & MF_TELEPORT)
			&& tm.ceilingz - thing->z < thing->height
			&& !(thing->flags3 & MF3_CEILINGHUGGER)
			&& (!(thing->flags2 & MF2_FLY) || !(thing->flags & MF_NOGRAVITY)))
		{
			goto pushline;		// mobj must lower itself to fit
		}
		if (thing->flags2 & MF2_FLY && thing->flags & MF_NOGRAVITY)
		{
#if 1
			if (thing->z+thing->height > tm.ceilingz)
				goto pushline;
#else
			// When flying, slide up or down blocking lines until the actor
			// is not blocked.
			if (thing->z+thing->height > tm.ceilingz)
			{
				thing->velz = -8*FRACUNIT;
				goto pushline;
			}
			else if (thing->z < tm.floorz && tm.floorz-tm.dropoffz > thing->MaxDropOffHeight)
			{
				thing->velz = 8*FRACUNIT;
				goto pushline;
			}
#endif
		}
		if (!(thing->flags & MF_TELEPORT) && !(thing->flags3 & MF3_FLOORHUGGER))
		{
			if (tm.floorz-thing->z > thing->MaxStepHeight)
			{ // too big a step up
				goto pushline;
			}
			else if ((thing->flags & MF_MISSILE)&& !(thing->flags6 && MF6_STEPMISSILE) && tm.floorz > thing->z)
			{ // [RH] Don't let normal missiles climb steps
				goto pushline;
			}
			else if (thing->z < tm.floorz)
			{ // [RH] Check to make sure there's nothing in the way for the step up
				fixed_t savedz = thing->z;
				bool good;
				thing->z = tm.floorz;
				good = P_TestMobjZ (thing);
				thing->z = savedz;
				if (!good)
				{
					goto pushline;
				}
			}
		}

		// compatibility check: Doom originally did not allow monsters to cross dropoffs at all.
		// If the compatibility flag is on, only allow this when the velocity comes from a scroller
		if ((i_compatflags & COMPATF_CROSSDROPOFF) && !(thing->flags4 & MF4_SCROLLMOVE))
		{
			dropoff = false;
		}

		if (dropoff==2 &&  // large jump down (e.g. dogs)
			(tm.floorz-tm.dropoffz > 128*FRACUNIT || thing->target == NULL || thing->target->z >tm.dropoffz))
		{
				dropoff = false;
		}


		// killough 3/15/98: Allow certain objects to drop off
		if ((!dropoff && !(thing->flags & (MF_DROPOFF|MF_FLOAT|MF_MISSILE))) || (thing->flags5&MF5_NODROPOFF))
		{
			if (!(thing->flags5&MF5_AVOIDINGDROPOFF))
			{
				fixed_t floorz = tm.floorz;
				// [RH] If the thing is standing on something, use its current z as the floorz.
				// This is so that it does not walk off of things onto a drop off.
				if (thing->flags2 & MF2_ONMOBJ)
				{
					floorz = MAX(thing->z, tm.floorz);
				}
				
				if (floorz - tm.dropoffz > thing->MaxDropOffHeight &&
					!(thing->flags2 & MF2_BLASTED))
				{ // Can't move over a dropoff unless it's been blasted
					thing->z = oldz;
					return false;
				}
			}
			else
			{
				// special logic to move a monster off a dropoff
				// this intentionally does not check for standing on things.
				if (thing->floorz - tm.floorz > thing->MaxDropOffHeight ||
					thing->dropoffz - tm.dropoffz > thing->MaxDropOffHeight) return false;
			}
		}
		if (thing->flags2 & MF2_CANTLEAVEFLOORPIC
			&& (tm.floorpic != thing->floorpic
				|| tm.floorz - thing->z != 0))
		{ // must stay within a sector of a certain floor type
			thing->z = oldz;
			return false;
		}
		
		//Added by MC: To prevent bot from getting into dangerous sectors.
		if (thing->player && thing->player->isbot && thing->flags & MF_SHOOTABLE)
		{
			if (tm.sector != thing->Sector
				&& bglobal.IsDangerous (tm.sector))
			{
				thing->player->prev = thing->player->dest;
				thing->player->dest = NULL;
				thing->velx = 0;
				thing->vely = 0;
				thing->z = oldz;
				return false;
			}
		} 
	}

	// [RH] Check status of eyes against fake floor/ceiling in case
	// it slopes or the player's eyes are bobbing in and out.

	bool oldAboveFakeFloor, oldAboveFakeCeiling;
	fixed_t viewheight;
	
	viewheight = thing->player ? thing->player->viewheight : thing->height / 2;
	oldAboveFakeFloor = oldAboveFakeCeiling = false;	// pacify GCC

	if (oldsec->heightsec)
	{
		fixed_t eyez = oldz + viewheight;

		oldAboveFakeFloor = eyez > oldsec->heightsec->floorplane.ZatPoint (thing->x, thing->y);
		oldAboveFakeCeiling = eyez > oldsec->heightsec->ceilingplane.ZatPoint (thing->x, thing->y);
	}

	// Borrowed from MBF: 
	if (thing->BounceFlags & BOUNCE_MBF &&  // killough 8/13/98
			!(thing->flags & (MF_MISSILE|MF_NOGRAVITY)) &&
			!thing->IsSentient() && tm.floorz - thing->z > 16*FRACUNIT)
	return false; // too big a step up for MBF bouncers under gravity

	// the move is ok, so link the thing into its new position
	thing->UnlinkFromWorld ();

	oldx = thing->x;
	oldy = thing->y;
	thing->floorz = tm.floorz;
	thing->ceilingz = tm.ceilingz;
	thing->dropoffz = tm.dropoffz;		// killough 11/98: keep track of dropoffs
	thing->floorpic = tm.floorpic;
	thing->floorsector = tm.floorsector;
	thing->ceilingpic = tm.ceilingpic;
	thing->ceilingsector = tm.ceilingsector;
	thing->x = x;
	thing->y = y;

	thing->LinkToWorld ();

	if (thing->flags2 & MF2_FLOORCLIP)
	{
		thing->AdjustFloorClip ();
	}

	// [RH] Don't activate anything if just predicting
	if (thing->player && (thing->player->cheats & CF_PREDICTING))
	{
		return true;
	}

	// if any special lines were hit, do the effect
	if (!(thing->flags & (MF_TELEPORT|MF_NOCLIP)))
	{
		while (spechit.Pop (ld))
		{
			// see if the line was crossed
			side = P_PointOnLineSide (thing->x, thing->y, ld);
			oldside = P_PointOnLineSide (oldx, oldy, ld);
			if (side != oldside && ld->special)
			{
				if (thing->player)
				{
					P_ActivateLine (ld, thing, oldside, SPAC_Cross);
				}
				else if (thing->flags2 & MF2_MCROSS)
				{
					P_ActivateLine (ld, thing, oldside, SPAC_MCross);
				}
				else if (thing->flags2 & MF2_PCROSS)
				{
					P_ActivateLine (ld, thing, oldside, SPAC_PCross);
				}
				else if ((ld->special == Teleport ||
						  ld->special == Teleport_NoFog ||
						  ld->special == Teleport_Line))
				{	// [RH] Just a little hack for BOOM compatibility
					P_ActivateLine (ld, thing, oldside, SPAC_MCross);
				}
				else
				{
					P_ActivateLine (ld, thing, oldside, SPAC_AnyCross);
				}
			}
		}
	}

	// [RH] Check for crossing fake floor/ceiling
	newsec = thing->Sector;
	if (newsec->heightsec && oldsec->heightsec && newsec->SecActTarget)
	{
		const sector_t *hs = newsec->heightsec;
		fixed_t eyez = thing->z + viewheight;
		fixed_t fakez = hs->floorplane.ZatPoint (x, y);

		if (!oldAboveFakeFloor && eyez > fakez)
		{ // View went above fake floor
			newsec->SecActTarget->TriggerAction (thing, SECSPAC_EyesSurface);
		}
		else if (oldAboveFakeFloor && eyez <= fakez)
		{ // View went below fake floor
			newsec->SecActTarget->TriggerAction (thing, SECSPAC_EyesDive);
		}

		if (!(hs->MoreFlags & SECF_FAKEFLOORONLY))
		{
			fakez = hs->ceilingplane.ZatPoint (x, y);
			if (!oldAboveFakeCeiling && eyez > fakez)
			{ // View went above fake ceiling
				newsec->SecActTarget->TriggerAction (thing, SECSPAC_EyesAboveC);
			}
			else if (oldAboveFakeCeiling && eyez <= fakez)
			{ // View went below fake ceiling
				newsec->SecActTarget->TriggerAction (thing, SECSPAC_EyesBelowC);
			}
		}
	}

	// [RH] If changing sectors, trigger transitions
	if (oldsec != newsec)
	{
		if (oldsec->SecActTarget)
		{
			oldsec->SecActTarget->TriggerAction (thing, SECSPAC_Exit);
		}
		if (newsec->SecActTarget)
		{
			int act = SECSPAC_Enter;
			if (thing->z <= newsec->floorplane.ZatPoint (thing->x, thing->y))
			{
				act |= SECSPAC_HitFloor;
			}
			if (thing->z + thing->height >= newsec->ceilingplane.ZatPoint (thing->x, thing->y))
			{
				act |= SECSPAC_HitCeiling;
			}
			if (newsec->heightsec &&
				thing->z == newsec->heightsec->floorplane.ZatPoint (thing->x, thing->y))
			{
				act |= SECSPAC_HitFakeFloor;
			}
			newsec->SecActTarget->TriggerAction (thing, act);
		}
	}
	return true;

pushline:
	// [RH] Don't activate anything if just predicting
	if (thing->player && (thing->player->cheats & CF_PREDICTING))
	{
		return false;
	}

	thing->z = oldz;
	if (!(thing->flags&(MF_TELEPORT|MF_NOCLIP)))
	{
		int numSpecHitTemp;

		if (tm.thing->flags2 & MF2_BLASTED)
		{
			P_DamageMobj (tm.thing, NULL, NULL, tm.thing->Mass >> 5, NAME_Melee);
		}
		numSpecHitTemp = (int)spechit.Size ();
		while (numSpecHitTemp > 0)
		{
			// see which lines were pushed
			ld = spechit[--numSpecHitTemp];
			side = P_PointOnLineSide (thing->x, thing->y, ld);
			CheckForPushSpecial (ld, side, thing);
		}
	}
	return false;
}

bool P_TryMove (AActor *thing, fixed_t x, fixed_t y,
				int dropoff, // killough 3/15/98: allow dropoff as option
				const secplane_t *onfloor) // [RH] Let P_TryMove keep the thing on the floor
{
	FCheckPosition tm;
	return P_TryMove(thing, x, y, dropoff, onfloor, tm);
}



//
// P_CheckMove
// Similar to P_TryMove but doesn't actually move the actor. Used for polyobject crushing
//

bool P_CheckMove(AActor *thing, fixed_t x, fixed_t y)
{
	FCheckPosition tm;
	fixed_t		newz = thing->z;

	if (!P_CheckPosition (thing, x, y, tm))
	{
		return false;
	}

	if (thing->flags3 & MF3_FLOORHUGGER)
	{
		newz = tm.floorz;
	}
	else if (thing->flags3 & MF3_CEILINGHUGGER)
	{
		newz = tm.ceilingz - thing->height;
	}

	if (!(thing->flags & MF_NOCLIP))
	{
		if (tm.ceilingz - tm.floorz < thing->height)
		{
			return false;
		}

		if (!(thing->flags & MF_TELEPORT)
			&& tm.ceilingz - newz < thing->height
			&& !(thing->flags3 & MF3_CEILINGHUGGER)
			&& (!(thing->flags2 & MF2_FLY) || !(thing->flags & MF_NOGRAVITY)))
		{
			return false;
		}
		if (thing->flags2 & MF2_FLY && thing->flags & MF_NOGRAVITY)
		{
			if (thing->z+thing->height > tm.ceilingz)
				return false;
		}
		if (!(thing->flags & MF_TELEPORT) && !(thing->flags3 & MF3_FLOORHUGGER))
		{
			if (tm.floorz-newz > thing->MaxStepHeight)
			{ // too big a step up
				return false;
			}
			else if ((thing->flags & MF_MISSILE) && !(thing->flags6 && MF6_STEPMISSILE) && tm.floorz > newz)
			{ // [RH] Don't let normal missiles climb steps
				return false;
			}
			else if (newz < tm.floorz)
			{ // [RH] Check to make sure there's nothing in the way for the step up
				fixed_t savedz = thing->z;
				thing->z = newz = tm.floorz;
				bool good = P_TestMobjZ (thing);
				thing->z = savedz;
				if (!good)
				{
					return false;
				}
			}
		}

		if (thing->flags2 & MF2_CANTLEAVEFLOORPIC
			&& (tm.floorpic != thing->floorpic
				|| tm.floorz - newz != 0))
		{ // must stay within a sector of a certain floor type
			return false;
		}
	}

	return true;
}



//
// SLIDE MOVE
// Allows the player to slide along any angled walls.
//
struct FSlide
{
	fixed_t 		bestslidefrac;
	fixed_t 		secondslidefrac;

	line_t* 		bestslideline;
	line_t* 		secondslideline;

	AActor* 		slidemo;

	fixed_t 		tmxmove;
	fixed_t 		tmymove;

	void HitSlideLine(line_t *ld);
	void SlideTraverse (fixed_t startx, fixed_t starty, fixed_t endx, fixed_t endy);
	void SlideMove (AActor *mo, fixed_t tryx, fixed_t tryy, int numsteps);

	// The bouncing code uses the same data structure
	bool BounceTraverse (fixed_t startx, fixed_t starty, fixed_t endx, fixed_t endy);
	bool BounceWall (AActor *mo);
};

//
// P_HitSlideLine
// Adjusts the xmove / ymove
// so that the next move will slide along the wall.
// If the floor is icy, then you can bounce off a wall.				// phares
//
void FSlide::HitSlideLine (line_t* ld)
{
	int 	side;

	angle_t lineangle;
	angle_t moveangle;
	angle_t deltaangle;
	
	fixed_t movelen;
	bool	icyfloor;	// is floor icy?							// phares
																	//   |
	// Under icy conditions, if the angle of approach to the wall	//   V
	// is more than 45 degrees, then you'll bounce and lose half
	// your velocity. If less than 45 degrees, you'll slide along
	// the wall. 45 is arbitrary and is believable.

	// Check for the special cases of horz or vert walls.

	// killough 10/98: only bounce if hit hard (prevents wobbling)
	icyfloor = 
		(P_AproxDistance(tmxmove, tmymove) > 4*FRACUNIT) &&
		var_friction &&  // killough 8/28/98: calc friction on demand
		slidemo->z <= slidemo->floorz &&
		P_GetFriction (slidemo, NULL) > ORIG_FRICTION;

	if (ld->slopetype == ST_HORIZONTAL)
	{
		if (icyfloor && (abs(tmymove) > abs(tmxmove)))
		{
			tmxmove /= 2; // absorb half the velocity
			tmymove = -tmymove/2;
			if (slidemo->player && slidemo->health > 0 && !(slidemo->player->cheats & CF_PREDICTING))
			{
				S_Sound (slidemo, CHAN_VOICE, "*grunt", 1, ATTN_IDLE); // oooff!
			}
		}
		else
			tmymove = 0; // no more movement in the Y direction
		return;
	}

	if (ld->slopetype == ST_VERTICAL)
	{
		if (icyfloor && (abs(tmxmove) > abs(tmymove)))
		{
			tmxmove = -tmxmove/2; // absorb half the velocity
			tmymove /= 2;
			if (slidemo->player && slidemo->health > 0 && !(slidemo->player->cheats & CF_PREDICTING))
			{
				S_Sound (slidemo, CHAN_VOICE, "*grunt", 1, ATTN_IDLE); // oooff!//   ^
			}
		}																		//   |
		else																	// phares
			tmxmove = 0; // no more movement in the X direction
		return;
	}

	// The wall is angled. Bounce if the angle of approach is		// phares
	// less than 45 degrees.										// phares

	side = P_PointOnLineSide (slidemo->x, slidemo->y, ld);

	lineangle = R_PointToAngle2 (0,0, ld->dx, ld->dy);

	if (side == 1)
		lineangle += ANG180;

	moveangle = R_PointToAngle2 (0,0, tmxmove, tmymove);

	moveangle += 10;		// prevents sudden path reversal due to	// phares
							// rounding error						//   |
	deltaangle = moveangle-lineangle;								//   V
	movelen = P_AproxDistance (tmxmove, tmymove);
	if (icyfloor && (deltaangle > ANG45) && (deltaangle < ANG90+ANG45))
	{
		moveangle = lineangle - deltaangle;
		movelen /= 2; // absorb
		if (slidemo->player && slidemo->health > 0 && !(slidemo->player->cheats & CF_PREDICTING))
		{
			S_Sound (slidemo, CHAN_VOICE, "*grunt", 1, ATTN_IDLE); // oooff!
		}
		moveangle >>= ANGLETOFINESHIFT;
		tmxmove = FixedMul (movelen, finecosine[moveangle]);
		tmymove = FixedMul (movelen, finesine[moveangle]);
	}																//   ^
	else															//   |
	{																// phares
#if 0
		fixed_t newlen;
	
		if (deltaangle > ANG180)
			deltaangle += ANG180;
		//	I_Error ("SlideLine: ang>ANG180");

		lineangle >>= ANGLETOFINESHIFT;
		deltaangle >>= ANGLETOFINESHIFT;

		newlen = FixedMul (movelen, finecosine[deltaangle]);

		tmxmove = FixedMul (newlen, finecosine[lineangle]);
		tmymove = FixedMul (newlen, finesine[lineangle]);
#else
		divline_t dll, dlv;
		fixed_t inter1, inter2, inter3;

		P_MakeDivline (ld, &dll);

		dlv.x = slidemo->x;
		dlv.y = slidemo->y;
		dlv.dx = dll.dy;
		dlv.dy = -dll.dx;

		inter1 = P_InterceptVector(&dll, &dlv);

		dlv.dx = tmxmove;
		dlv.dy = tmymove;
		inter2 = P_InterceptVector (&dll, &dlv);
		inter3 = P_InterceptVector (&dlv, &dll);

		if (inter3 != 0)
		{
			tmxmove = Scale (inter2-inter1, dll.dx, inter3);
			tmymove = Scale (inter2-inter1, dll.dy, inter3);
		}
		else
		{
			tmxmove = tmymove = 0;
		}
#endif
	}																// phares
}


//
// PTR_SlideTraverse
//
void FSlide::SlideTraverse (fixed_t startx, fixed_t starty, fixed_t endx, fixed_t endy)
{
	FLineOpening open;
	FPathTraverse it(startx, starty, endx, endy, PT_ADDLINES);
	intercept_t *in;

	while ((in = it.Next()))
	{
		line_t* 	li;
			
		if (!in->isaline)
		{
			// should never happen
			Printf ("PTR_SlideTraverse: not a line?");
			continue;
		}
					
		li = in->d.line;
		
		if ( !(li->flags & ML_TWOSIDED) || !li->backsector )
		{
			if (P_PointOnLineSide (slidemo->x, slidemo->y, li))
			{
				// don't hit the back side
				continue;				
			}
			goto isblocking;
		}
		if (li->flags & (ML_BLOCKING|ML_BLOCKEVERYTHING))
		{
			goto isblocking;
		}
		if (li->flags & ML_BLOCK_PLAYERS && slidemo->player != NULL)
		{
			goto isblocking;
		}
		if (li->flags & ML_BLOCKMONSTERS && !((slidemo->flags3 & MF3_NOBLOCKMONST)
			|| ((i_compatflags & COMPATF_NOBLOCKFRIENDS) && (slidemo->flags & MF_FRIENDLY))))
		{
			goto isblocking;
		}

		// set openrange, opentop, openbottom
		P_LineOpening (open, slidemo, li, it.Trace().x + FixedMul (it.Trace().dx, in->frac),
			it.Trace().y + FixedMul (it.Trace().dy, in->frac));
		
		if (open.range < slidemo->height)
			goto isblocking;				// doesn't fit
					
		if (open.top - slidemo->z < slidemo->height)
			goto isblocking;				// mobj is too high

		if (open.bottom - slidemo->z > slidemo->MaxStepHeight)
		{
			goto isblocking;				// too big a step up
		}
		else if (slidemo->z < open.bottom)
		{ // [RH] Check to make sure there's nothing in the way for the step up
			fixed_t savedz = slidemo->z;
			slidemo->z = open.bottom;
			bool good = P_TestMobjZ (slidemo);
			slidemo->z = savedz;
			if (!good)
			{
				goto isblocking;
			}
		}

		// this line doesn't block movement
		continue;				
			
		// the line does block movement,
		// see if it is closer than best so far
	  isblocking:			
		if (in->frac < bestslidefrac)
		{
			secondslidefrac = bestslidefrac;
			secondslideline = bestslideline;
			bestslidefrac = in->frac;
			bestslideline = li;
		}
			
		return;		// stop
	}
}



//
// P_SlideMove
//
// The velx / vely move is bad, so try to slide along a wall.
//
// Find the first line hit, move flush to it, and slide along it
//
// This is a kludgy mess.
//
void FSlide::SlideMove (AActor *mo, fixed_t tryx, fixed_t tryy, int numsteps)
{
	fixed_t leadx, leady;
	fixed_t trailx, traily;
	fixed_t newx, newy;
	fixed_t xmove, ymove;
	const secplane_t * walkplane;
	int hitcount;

	hitcount = 3;
	slidemo = mo;

	if (mo->player && mo->reactiontime > 0)
		return;	// player coming right out of a teleporter.
	
  retry:
	if (!--hitcount)
		goto stairstep; 		// don't loop forever
	
	// trace along the three leading corners
	if (tryx > 0)
	{
		leadx = mo->x + mo->radius;
		trailx = mo->x - mo->radius;
	}
	else
	{
		leadx = mo->x - mo->radius;
		trailx = mo->x + mo->radius;
	}

	if (tryy > 0)
	{
		leady = mo->y + mo->radius;
		traily = mo->y - mo->radius;
	}
	else
	{
		leady = mo->y - mo->radius;
		traily = mo->y + mo->radius;
	}

	bestslidefrac = FRACUNIT+1;
		
	SlideTraverse (leadx, leady, leadx+tryx, leady+tryy);
	SlideTraverse (trailx, leady, trailx+tryx, leady+tryy);
	SlideTraverse (leadx, traily, leadx+tryx, traily+tryy);

	// move up to the wall
	if (bestslidefrac == FRACUNIT+1)
	{
		// the move must have hit the middle, so stairstep
	  stairstep:
		// killough 3/15/98: Allow objects to drop off ledges
		xmove = 0, ymove = tryy;
		walkplane = P_CheckSlopeWalk (mo, xmove, ymove);
		if (!P_TryMove (mo, mo->x + xmove, mo->y + ymove, true, walkplane))
		{
			xmove = tryx, ymove = 0;
			walkplane = P_CheckSlopeWalk (mo, xmove, ymove);
			P_TryMove (mo, mo->x + xmove, mo->y + ymove, true, walkplane);
		}
		return;
	}

	// fudge a bit to make sure it doesn't hit
	bestslidefrac -= FRACUNIT/32;
	if (bestslidefrac > 0)
	{
		newx = FixedMul (tryx, bestslidefrac);
		newy = FixedMul (tryy, bestslidefrac);
		
		// killough 3/15/98: Allow objects to drop off ledges
		if (!P_TryMove (mo, mo->x+newx, mo->y+newy, true))
			goto stairstep;
	}

	// Now continue along the wall.
	bestslidefrac = FRACUNIT - (bestslidefrac + FRACUNIT/32);	// remainder
	if (bestslidefrac > FRACUNIT)
		bestslidefrac = FRACUNIT;
	else if (bestslidefrac <= 0)
		return;

	tryx = tmxmove = FixedMul (tryx, bestslidefrac);
	tryy = tmymove = FixedMul (tryy, bestslidefrac);

	HitSlideLine (bestslideline); 	// clip the moves

	mo->velx = tmxmove * numsteps;
	mo->vely = tmymove * numsteps;

	// killough 10/98: affect the bobbing the same way (but not voodoo dolls)
	if (mo->player && mo->player->mo == mo)
	{
		if (abs(mo->player->velx) > abs(mo->velx))
			mo->player->velx = mo->velx;
		if (abs(mo->player->vely) > abs(mo->vely))
			mo->player->vely = mo->vely;
	}

	walkplane = P_CheckSlopeWalk (mo, tmxmove, tmymove);

	// killough 3/15/98: Allow objects to drop off ledges
	if (!P_TryMove (mo, mo->x+tmxmove, mo->y+tmymove, true, walkplane))
	{
		goto retry;
	}
}

void P_SlideMove (AActor *mo, fixed_t tryx, fixed_t tryy, int numsteps)
{
	FSlide slide;
	slide.SlideMove(mo, tryx, tryy, numsteps);
}

//============================================================================
//
// P_CheckSlopeWalk
//
//============================================================================

const secplane_t * P_CheckSlopeWalk (AActor *actor, fixed_t &xmove, fixed_t &ymove)
{
	static secplane_t copyplane;
	if (actor->flags & MF_NOGRAVITY)
	{
		return NULL;
	}

	const secplane_t *plane = &actor->floorsector->floorplane;
	fixed_t planezhere = plane->ZatPoint (actor->x, actor->y);

#ifdef _3DFLOORS
	for(unsigned int i=0;i<actor->floorsector->e->XFloor.ffloors.Size();i++)
	{
		F3DFloor * rover= actor->floorsector->e->XFloor.ffloors[i];
		if(!(rover->flags & FF_SOLID) || !(rover->flags & FF_EXISTS)) continue;

		fixed_t thisplanez = rover->top.plane->ZatPoint(actor->x, actor->y);

		if (thisplanez>planezhere && thisplanez<=actor->z + actor->MaxStepHeight)
		{
			copyplane = *rover->top.plane;
			if (copyplane.c<0) copyplane.FlipVert();
			plane = &copyplane;
			planezhere=thisplanez;
		}
	}

	if (actor->floorsector != actor->Sector)
	{
		for(unsigned int i=0;i<actor->Sector->e->XFloor.ffloors.Size();i++)
		{
			F3DFloor * rover= actor->Sector->e->XFloor.ffloors[i];
			if(!(rover->flags & FF_SOLID) || !(rover->flags & FF_EXISTS)) continue;

			fixed_t thisplanez = rover->top.plane->ZatPoint(actor->x, actor->y);

			if (thisplanez>planezhere && thisplanez<=actor->z + actor->MaxStepHeight)
			{
				copyplane = *rover->top.plane;
				if (copyplane.c<0) copyplane.FlipVert();
				plane = &copyplane;
				planezhere=thisplanez;
			}
		}
	}
#endif

	if (actor->floorsector != actor->Sector)
	{
		// this additional check prevents sliding on sloped dropoffs
		if (planezhere>actor->floorz+4*FRACUNIT)
			return NULL;
	}

	if (actor->z - planezhere > FRACUNIT)
	{ // not on floor
		return NULL;
	}

	if ((plane->a | plane->b) != 0)
	{
		fixed_t destx, desty;
		fixed_t t;

		destx = actor->x + xmove;
		desty = actor->y + ymove;
		t = TMulScale16 (plane->a, destx, plane->b, desty, plane->c, actor->z) + plane->d;
		if (t < 0)
		{ // Desired location is behind (below) the plane
		  // (i.e. Walking up the plane)
			if (plane->c < STEEPSLOPE)
			{ // Can't climb up slopes of ~45 degrees or more
				if (actor->flags & MF_NOCLIP)
				{
					return (actor->floorsector == actor->Sector) ? plane : NULL;
				}
				else
				{
					const msecnode_t *node;
					bool dopush = true;

					if (plane->c > STEEPSLOPE*2/3)
					{
						for (node = actor->touching_sectorlist; node; node = node->m_tnext)
						{
							const sector_t *sec = node->m_sector;
							if (sec->floorplane.c >= STEEPSLOPE)
							{
								if (sec->floorplane.ZatPoint (destx, desty) >= actor->z - actor->MaxStepHeight)
								{
									dopush = false;
									break;
								}
							}
						}
					}
					if (dopush)
					{
						xmove = actor->velx = plane->a * 2;
						ymove = actor->vely = plane->b * 2;
					}
					return (actor->floorsector == actor->Sector) ? plane : NULL;
				}
			}
			// Slide the desired location along the plane's normal
			// so that it lies on the plane's surface
			destx -= FixedMul (plane->a, t);
			desty -= FixedMul (plane->b, t);
			xmove = destx - actor->x;
			ymove = desty - actor->y;
			return (actor->floorsector == actor->Sector) ? plane : NULL;
		}
		else if (t > 0)
		{ // Desired location is in front of (above) the plane
			if (planezhere == actor->z)
			{ // Actor's current spot is on/in the plane, so walk down it
			  // Same principle as walking up, except reversed
				destx += FixedMul (plane->a, t);
				desty += FixedMul (plane->b, t);
				xmove = destx - actor->x;
				ymove = desty - actor->y;
				return (actor->floorsector == actor->Sector) ? plane : NULL;
			}
		}
	}
	return NULL;
}

//============================================================================
//
// PTR_BounceTraverse
//
//============================================================================

bool FSlide::BounceTraverse (fixed_t startx, fixed_t starty, fixed_t endx, fixed_t endy)
{
	FLineOpening open;
	FPathTraverse it(startx, starty, endx, endy, PT_ADDLINES);
	intercept_t *in;

	while ((in = it.Next()))
	{

		line_t  *li;

		if (!in->isaline)
		{
			Printf ("PTR_BounceTraverse: not a line?");
			continue;
		}

		li = in->d.line;
		assert(((size_t)li - (size_t)lines) % sizeof(line_t) == 0);
		if (li->flags & ML_BLOCKEVERYTHING)
		{
			goto bounceblocking;
		}
		if (!(li->flags&ML_TWOSIDED) || !li->backsector)
		{
			if (P_PointOnLineSide (slidemo->x, slidemo->y, li))
				continue;			// don't hit the back side
			goto bounceblocking;
		}


		P_LineOpening (open, slidemo, li, it.Trace().x + FixedMul (it.Trace().dx, in->frac),
			it.Trace().y + FixedMul (it.Trace().dy, in->frac));	// set openrange, opentop, openbottom
		if (open.range < slidemo->height)
			goto bounceblocking;				// doesn't fit

		if (open.top - slidemo->z < slidemo->height)
			goto bounceblocking;				// mobj is too high

		if (open.bottom > slidemo->z)
			goto bounceblocking;				// mobj is too low

		continue;			// this line doesn't block movement

	// the line does block movement, see if it is closer than best so far
	bounceblocking:
		if (in->frac < bestslidefrac)
		{
			secondslidefrac = bestslidefrac;
			secondslideline = bestslideline;
			bestslidefrac = in->frac;
			bestslideline = li;
		}
		return false;   // stop
	}
	return true;
}

//============================================================================
//
// P_BounceWall
//
//============================================================================

bool FSlide::BounceWall (AActor *mo)
{
	fixed_t         leadx, leady;
	int             side;
	angle_t         lineangle, moveangle, deltaangle;
	fixed_t         movelen;
	line_t			*line;

	if (!(mo->BounceFlags & BOUNCE_Walls))
	{
		return false;
	}

	slidemo = mo;
//
// trace along the three leading corners
//
	if (mo->velx > 0)
	{
		leadx = mo->x+mo->radius;
	}
	else
	{
		leadx = mo->x-mo->radius;
	}
	if (mo->vely > 0)
	{
		leady = mo->y+mo->radius;
	}
	else
	{
		leady = mo->y-mo->radius;
	}
	bestslidefrac = FRACUNIT+1;
	bestslideline = mo->BlockingLine;
	if (BounceTraverse(leadx, leady, leadx+mo->velx, leady+mo->vely) && mo->BlockingLine == NULL)
	{ // Could not find a wall, so bounce off the floor/ceiling instead.
		fixed_t floordist = mo->z - mo->floorz;
		fixed_t ceildist = mo->ceilingz - mo->z;
		if (floordist <= ceildist)
		{
			mo->FloorBounceMissile (mo->Sector->floorplane);
			return true;
		}
		else
		{
			mo->FloorBounceMissile (mo->Sector->ceilingplane);
			return true;
		}
	}
	line = bestslideline;

	if (line->special == Line_Horizon)
	{
		mo->SeeSound = 0;	// it might make a sound otherwise
		mo->Destroy();
		return true;
	}

	// The amount of bounces is limited
	if (mo->bouncecount>0 && --mo->bouncecount==0)
	{
		if (mo->flags & MF_MISSILE)
			P_ExplodeMissile(mo, NULL, NULL);
		else
			mo->Die(NULL, NULL);
		return true;
	}

	side = P_PointOnLineSide (mo->x, mo->y, line);
	lineangle = R_PointToAngle2 (0, 0, line->dx, line->dy);
	if (side == 1)
	{
		lineangle += ANG180;
	}
	moveangle = R_PointToAngle2 (0, 0, mo->velx, mo->vely);
	deltaangle = (2*lineangle)-moveangle;
	mo->angle = deltaangle;

	lineangle >>= ANGLETOFINESHIFT;
	deltaangle >>= ANGLETOFINESHIFT;

	movelen = fixed_t(sqrt(double(mo->velx)*mo->velx + double(mo->vely)*mo->vely));
	movelen = FixedMul(movelen, mo->wallbouncefactor);

	FBoundingBox box(mo->x, mo->y, mo->radius);
	if (box.BoxOnLineSide (line) == -1)
	{
		mo->SetOrigin (mo->x + FixedMul(mo->radius,
			finecosine[deltaangle]), mo->y + FixedMul(mo->radius, finesine[deltaangle]), mo->z);
	}
	if (movelen < FRACUNIT)
	{
		movelen = 2*FRACUNIT;
	}
	mo->velx = FixedMul(movelen, finecosine[deltaangle]);
	mo->vely = FixedMul(movelen, finesine[deltaangle]);
	return true;
}

bool P_BounceWall (AActor *mo)
{
	FSlide slide;
	return slide.BounceWall(mo);
}

extern FRandom pr_bounce;
bool P_BounceActor (AActor *mo, AActor * BlockingMobj)
{
	if (mo && BlockingMobj && ((mo->BounceFlags & BOUNCE_AllActors)
		|| ((mo->flags & MF_MISSILE) && (BlockingMobj->flags2 & MF2_REFLECTIVE)
		|| ((!BlockingMobj->player) && (!(BlockingMobj->flags3 & MF3_ISMONSTER))))
		))
	{
		fixed_t speed;
		angle_t angle = R_PointToAngle2 (BlockingMobj->x,
		BlockingMobj->y, mo->x, mo->y) + ANGLE_1*((pr_bounce()%16)-8);
		speed = P_AproxDistance (mo->velx, mo->vely);
		speed = FixedMul (speed, mo->wallbouncefactor); // [GZ] was 0.75, using wallbouncefactor seems more consistent
		mo->angle = angle;
		angle >>= ANGLETOFINESHIFT;
		mo->velx = FixedMul (speed, finecosine[angle]);
		mo->vely = FixedMul (speed, finesine[angle]);
		mo->PlayBounceSound(true);
		return true;
	}
	else return false;
}

//============================================================================
//
// Aiming
//
//============================================================================

struct aim_t
{
	fixed_t			aimpitch;
	fixed_t			attackrange;
	fixed_t			shootz;			// Height if not aiming up or down
	AActor*			shootthing;

	fixed_t			toppitch, bottompitch;
	AActor *		linetarget;
	AActor *		thing_friend, * thing_other;
	angle_t			pitch_friend, pitch_other;
	bool			notsmart;
	bool			check3d;
#ifdef _3DFLOORS
	sector_t *		lastsector;
	secplane_t *	lastfloorplane;
	secplane_t *	lastceilingplane;

	bool			crossedffloors;

	bool AimTraverse3DFloors(const divline_t &trace, intercept_t * in);
#endif

	void AimTraverse (fixed_t startx, fixed_t starty, fixed_t endx, fixed_t endy, bool checknonshootable = false);

};

#ifdef _3DFLOORS
//============================================================================
//
// AimTraverse3DFloors
//
//============================================================================
bool aim_t::AimTraverse3DFloors(const divline_t &trace, intercept_t * in)
{
	sector_t * nextsector;
	secplane_t * nexttopplane, * nextbottomplane;
	line_t * li=in->d.line;

	nextsector=NULL;
	nexttopplane=nextbottomplane=NULL;

    if(li->frontsector->e->XFloor.ffloors.Size() || li->backsector->e->XFloor.ffloors.Size())
    {
		int  frontflag;
		F3DFloor* rover;
		int    highpitch, lowpitch;

		fixed_t trX = trace.x + FixedMul (trace.dx, in->frac);
		fixed_t trY = trace.y + FixedMul (trace.dy, in->frac);
		fixed_t dist = FixedMul (attackrange, in->frac);

		
		int dir = aimpitch < 0 ? 1 : aimpitch > 0 ? -1 : 0;
		
		frontflag = P_PointOnLineSide(shootthing->x, shootthing->y, li);
		
		// 3D floor check. This is not 100% accurate but normally sufficient when
		// combined with a final sight check
		for(int i=1;i<=2;i++)
		{
			sector_t * s=i==1? li->frontsector:li->backsector;

			for(unsigned k=0;k<s->e->XFloor.ffloors.Size();k++)
			{
				crossedffloors=true;
				rover=s->e->XFloor.ffloors[k];
			
				if((rover->flags & FF_SHOOTTHROUGH) || !(rover->flags & FF_EXISTS)) continue;
				
				fixed_t ff_bottom=rover->bottom.plane->ZatPoint(trX, trY);
				fixed_t ff_top=rover->top.plane->ZatPoint(trX, trY);
				

				highpitch = -(int)R_PointToAngle2 (0, shootz, dist, ff_top);
				lowpitch = -(int)R_PointToAngle2 (0, shootz, dist, ff_bottom);

				if (highpitch<=toppitch)
				{
					// blocks completely
					if (lowpitch>=bottompitch) return false;	
					// blocks upper edge of view
					if (lowpitch>toppitch) 
					{
						toppitch=lowpitch;
						if (frontflag!=i-1)
						{
							nexttopplane=rover->bottom.plane;
						}
					}
				}
				else if (lowpitch>=bottompitch)
				{
					// blocks lower edge of view
					if (highpitch<bottompitch)  
					{
						bottompitch=highpitch;
						if (frontflag!=i-1)
						{
							nextbottomplane=rover->top.plane;
						}
					}
				}
				// trace is leaving a sector with a 3d-floor

				if (frontflag==i-1)
				{
					if (s==lastsector)
					{
						// upper slope intersects with this 3d-floor
						if (rover->bottom.plane==lastceilingplane && lowpitch > toppitch)
						{
							toppitch=lowpitch;
						}
						// lower slope intersects with this 3d-floor
						if (rover->top.plane==lastfloorplane && highpitch < bottompitch)
						{
							bottompitch=highpitch;
						}
					}
				}
				if (toppitch >= bottompitch) return false;		// stop
			}
		}
    }

	lastsector=nextsector;
	lastceilingplane=nexttopplane;
	lastfloorplane=nextbottomplane;
	return true;
}
#endif

//============================================================================
//
// PTR_AimTraverse
// Sets linetaget and aimpitch when a target is aimed at.
//
//============================================================================

void aim_t::AimTraverse (fixed_t startx, fixed_t starty, fixed_t endx, fixed_t endy, bool checknonshootable)
{
	FPathTraverse it(startx, starty, endx, endy, PT_ADDLINES|PT_ADDTHINGS);
	intercept_t *in;

	while ((in = it.Next()))
	{
		line_t* 			li;
		AActor* 			th;
		fixed_t 			pitch;
		fixed_t 			thingtoppitch;
		fixed_t 			thingbottompitch;
		fixed_t 			dist;
		int					thingpitch;

		if (in->isaline) 
		{
			li = in->d.line;

			if ( !(li->flags & ML_TWOSIDED) || (li->flags & ML_BLOCKEVERYTHING) )
				return;				// stop

			// Crosses a two sided line.
			// A two sided line will restrict the possible target ranges.
			FLineOpening open;
			P_LineOpening (open, NULL, li, it.Trace().x + FixedMul (it.Trace().dx, in->frac),
				it.Trace().y + FixedMul (it.Trace().dy, in->frac));

			if (open.bottom >= open.top)
				return;				// stop

			dist = FixedMul (attackrange, in->frac);

			pitch = -(int)R_PointToAngle2 (0, shootz, dist, open.bottom);
			if (pitch < bottompitch)
				bottompitch = pitch;

			pitch = -(int)R_PointToAngle2 (0, shootz, dist, open.top);
			if (pitch > toppitch)
				toppitch = pitch;

			if (toppitch >= bottompitch)
				return;				// stop
						
#ifdef _3DFLOORS
			if (!AimTraverse3DFloors(it.Trace(), in)) return;
#endif
			continue;					// shot continues
		}

		// shoot a thing
		th = in->d.thing;
		if (th == shootthing)
			continue;					// can't shoot self

		if (!checknonshootable)			// For info CCMD, ignore stuff about GHOST and SHOOTABLE flags
		{
 			if (!(th->flags&MF_SHOOTABLE))
				continue;					// corpse or something

			// check for physical attacks on a ghost
			if ((th->flags3 & MF3_GHOST) && 
				shootthing->player &&	// [RH] Be sure shootthing is a player
				shootthing->player->ReadyWeapon &&
				(shootthing->player->ReadyWeapon->flags2 & MF2_THRUGHOST))
			{
				continue;
			}
		}
		dist = FixedMul (attackrange, in->frac);

#ifdef _3DFLOORS
		// we must do one last check whether the trace has crossed a 3D floor
		if (lastsector==th->Sector && th->Sector->e->XFloor.ffloors.Size())
		{
			if (lastceilingplane)
			{
				fixed_t ff_top=lastceilingplane->ZatPoint(th->x, th->y);
				fixed_t pitch = -(int)R_PointToAngle2 (0, shootz, dist, ff_top);
				// upper slope intersects with this 3d-floor
				if (pitch > toppitch)
				{
					toppitch=pitch;
				}
			}
			if (lastfloorplane)
			{
				fixed_t ff_bottom=lastfloorplane->ZatPoint(th->x, th->y);
				fixed_t pitch = -(int)R_PointToAngle2 (0, shootz, dist, ff_bottom);
				// lower slope intersects with this 3d-floor
				if (pitch < bottompitch)
				{
					bottompitch=pitch;
				}
			}
		}
#endif

		// check angles to see if the thing can be aimed at

		thingtoppitch = -(int)R_PointToAngle2 (0, shootz, dist, th->z + th->height);

		if (thingtoppitch > bottompitch)
			continue;					// shot over the thing

		thingbottompitch = -(int)R_PointToAngle2 (0, shootz, dist, th->z);

		if (thingbottompitch < toppitch)
			continue;					// shot under the thing
		
#ifdef _3DFLOORS
		if (crossedffloors)
		{
			// if 3D floors were in the way do an extra visibility check for safety
			if (!P_CheckSight(shootthing, th, 1)) 
			{
				// the thing can't be seen so we can safely exclude its range from our aiming field
				if (thingtoppitch<toppitch) 
				{
					if (thingbottompitch>toppitch) toppitch=thingbottompitch;
				}
				else if (thingbottompitch>bottompitch)
				{
					if (thingtoppitch<bottompitch) bottompitch=thingtoppitch;
				}
				if (toppitch < bottompitch) continue;
				else return;
			}
		}
#endif

		// this thing can be hit!
		if (thingtoppitch < toppitch)
			thingtoppitch = toppitch;

		if (thingbottompitch > bottompitch)
			thingbottompitch = bottompitch;
		
		thingpitch = thingtoppitch/2 + thingbottompitch/2;
		
		if (check3d)
		{
			// We need to do a 3D distance check here because this is nearly always used in
			// combination with P_LineAttack. P_LineAttack uses 3D distance but FPathTraverse
			// only 2D. This causes some problems with Hexen's weapons that use different
			// attack modes based on distance to target
			fixed_t cosine = finecosine[thingpitch >> ANGLETOFINESHIFT];
			if (cosine != 0)
			{
				fixed_t d3 = FixedDiv( FixedMul( P_AproxDistance(it.Trace().dx, it.Trace().dy), in->frac), cosine);
				if (d3 > attackrange)
				{
					return;
				}
			}
		}

		if (sv_smartaim && !notsmart)
		{
			// try to be a little smarter about what to aim at!
			// In particular avoid autoaiming at friends amd barrels.
			if (th->IsFriend(shootthing))
			{
				if (sv_smartaim < 2)
				{
					// friends don't aim at friends (except players), at least not first
					thing_friend=th;
					pitch_friend=thingpitch;
				}
			}
			else if (!(th->flags3&MF3_ISMONSTER) && th->player == NULL)
			{
				if (sv_smartaim < 3)
				{
					// don't autoaim at barrels and other shootable stuff unless no monsters have been found
					thing_other=th;
					pitch_other=thingpitch;
				}
			}
			else
			{
				linetarget=th;
				aimpitch=thingpitch;
				return;
			}
		}
		else
		{
			linetarget=th;
			aimpitch=thingpitch;
			return;
		}
		if (checknonshootable)
		{
			linetarget=th;
			aimpitch=thingpitch;
		}
	}
}

//============================================================================
//
// P_AimLineAttack
//
//============================================================================
fixed_t P_AimLineAttack (AActor *t1, angle_t angle, fixed_t distance, AActor **pLineTarget, fixed_t vrange, bool forcenosmart, bool check3d, bool checknonshootable)
{
	fixed_t x2;
	fixed_t y2;
	aim_t aim;

	angle >>= ANGLETOFINESHIFT;
	aim.shootthing = t1;
	aim.check3d = check3d;

	x2 = t1->x + (distance>>FRACBITS)*finecosine[angle];
	y2 = t1->y + (distance>>FRACBITS)*finesine[angle];
	aim.shootz = t1->z + (t1->height>>1) - t1->floorclip;
	if (t1->player != NULL)
	{
		aim.shootz += FixedMul (t1->player->mo->AttackZOffset, t1->player->crouchfactor);
	}
	else
	{
		aim.shootz += 8*FRACUNIT;
	}

	// can't shoot outside view angles
	if (vrange == 0)
	{
		if (t1->player == NULL || !level.IsFreelookAllowed())
		{
			vrange = ANGLE_1*35;
		}
		else
		{
			// 35 degrees is approximately what Doom used. You cannot have a
			// vrange of 0 degrees, because then toppitch and bottompitch will
			// be equal, and PTR_AimTraverse will never find anything to shoot at
			// if it crosses a line.
			vrange = clamp (t1->player->userinfo.GetAimDist(), ANGLE_1/2, ANGLE_1*35);
		}
	}
	aim.toppitch = t1->pitch - vrange;
	aim.bottompitch = t1->pitch + vrange;
	aim.notsmart = forcenosmart;

	aim.attackrange = distance;
	aim.linetarget = NULL;

	// for smart aiming
	aim.thing_friend=aim.thing_other=NULL;

	// Information for tracking crossed 3D floors
	aim.aimpitch=t1->pitch;

#ifdef _3DFLOORS
	aim.crossedffloors=t1->Sector->e->XFloor.ffloors.Size()!=0;
	aim.lastsector=t1->Sector;
	aim.lastfloorplane=aim.lastceilingplane=NULL;

	// set initial 3d-floor info
	for(unsigned i=0;i<t1->Sector->e->XFloor.ffloors.Size();i++)
	{
		F3DFloor * rover=t1->Sector->e->XFloor.ffloors[i];
		fixed_t bottomz=rover->bottom.plane->ZatPoint(t1->x, t1->y);

		if (bottomz>=t1->z+t1->height) aim.lastceilingplane=rover->bottom.plane;

		bottomz=rover->top.plane->ZatPoint(t1->x, t1->y);
		if (bottomz<=t1->z) aim.lastfloorplane=rover->top.plane;
	}
#endif

	aim.AimTraverse (t1->x, t1->y, x2, y2, checknonshootable);

	if (!aim.linetarget) 
	{
		if (aim.thing_other)
		{
			aim.linetarget=aim.thing_other;
			aim.aimpitch=aim.pitch_other;
		}
		else if (aim.thing_friend)
		{
			aim.linetarget=aim.thing_friend;
			aim.aimpitch=aim.pitch_friend;
		}
	}
	if (pLineTarget) *pLineTarget = aim.linetarget;
	return aim.linetarget ? aim.aimpitch : t1->pitch;
}


/*
=================
=
= P_LineAttack
=
= if damage == 0, it is just a test trace that will leave linetarget set
=
=================
*/

static bool CheckForGhost (FTraceResults &res)
{
	if (res.HitType != TRACE_HitActor)
	{
		return false;
	}

	// check for physical attacks on a ghost
	if (res.Actor->flags3 & MF3_GHOST || res.Actor->flags4 & MF4_SPECTRAL)
	{
		res.HitType = TRACE_HitNone;
		return true;
	}

	return false;
}

static bool CheckForSpectral (FTraceResults &res)
{
	if (res.HitType != TRACE_HitActor)
	{
		return false;
	}

	// check for physical attacks on spectrals
	if (res.Actor->flags4 & MF4_SPECTRAL)
	{
		res.HitType = TRACE_HitNone;
		return true;
	}

	return false;
}

AActor *P_LineAttack (AActor *t1, angle_t angle, fixed_t distance,
				   int pitch, int damage, FName damageType, const PClass *pufftype, bool ismeleeattack)
{
	fixed_t vx, vy, vz, shootz;
	FTraceResults trace;
	angle_t srcangle = angle;
	int srcpitch = pitch;
	bool hitGhosts;
	bool killPuff = false;
	AActor *puff = NULL;
	int flags = ismeleeattack? PF_MELEERANGE : 0;

	angle >>= ANGLETOFINESHIFT;
	pitch = (angle_t)(pitch) >> ANGLETOFINESHIFT;

	vx = FixedMul (finecosine[pitch], finecosine[angle]);
	vy = FixedMul (finecosine[pitch], finesine[angle]);
	vz = -finesine[pitch];

	shootz = t1->z - t1->floorclip + (t1->height>>1);
	if (t1->player != NULL)
	{
		shootz += FixedMul (t1->player->mo->AttackZOffset, t1->player->crouchfactor);
	}
	else
	{
		shootz += 8*FRACUNIT;
	}

	hitGhosts = (t1->player != NULL &&
		t1->player->ReadyWeapon != NULL &&
		(t1->player->ReadyWeapon->flags2 & MF2_THRUGHOST));

	if (!Trace (t1->x, t1->y, shootz, t1->Sector, vx, vy, vz, distance,
		MF_SHOOTABLE, ML_BLOCKEVERYTHING, t1, trace,
		TRACE_NoSky|TRACE_Impact, hitGhosts ? CheckForGhost : CheckForSpectral))
	{ // hit nothing
		AActor *puffDefaults = GetDefaultByType (pufftype);
		if (puffDefaults->ActiveSound)
		{ // Play miss sound
			S_Sound (t1, CHAN_WEAPON, puffDefaults->ActiveSound, 1, ATTN_NORM);
		}
		if (puffDefaults->flags3 & MF3_ALWAYSPUFF)
		{ // Spawn the puff anyway
			puff = P_SpawnPuff (t1, pufftype, trace.X, trace.Y, trace.Z, angle - ANG180, 2, flags);
		}
		else
		{
			return NULL;
		}
	}
	else
	{
		fixed_t hitx = 0, hity = 0, hitz = 0;

		if (trace.HitType != TRACE_HitActor)
		{
			// position a bit closer for puffs
			if (trace.HitType != TRACE_HitWall || trace.Line->special != Line_Horizon)
			{
				fixed_t closer = trace.Distance - 4*FRACUNIT;
				puff = P_SpawnPuff (t1, pufftype, t1->x + FixedMul (vx, closer),
					t1->y + FixedMul (vy, closer),
					shootz + FixedMul (vz, closer), angle - ANG90, 0, flags);
			}

			// [RH] Spawn a decal
			if (trace.HitType == TRACE_HitWall && trace.Line->special != Line_Horizon)
			{				
				// [TN] If the actor or weapon has a decal defined, use that one.
				if(t1->DecalGenerator != NULL || 
					(t1->player != NULL && t1->player->ReadyWeapon != NULL && t1->player->ReadyWeapon->DecalGenerator != NULL))
				{
					SpawnShootDecal (t1, trace);
				}

				// Else, look if the bulletpuff has a decal defined.
				else if(puff != NULL && puff->DecalGenerator)
				{
					SpawnShootDecal (puff, trace);
				}				
				
				else
				{
					SpawnShootDecal (t1, trace);
				}				
			}
			else if (puff != NULL &&
				trace.CrossedWater == NULL &&
				trace.Sector->heightsec == NULL &&
				trace.HitType == TRACE_HitFloor)
			{
				// Using the puff's position is not accurate enough.
				// Instead make it splash at the actual hit position
				hitx = t1->x + FixedMul (vx, trace.Distance);
				hity = t1->y + FixedMul (vy, trace.Distance);
				hitz = shootz + FixedMul (vz, trace.Distance);
				P_HitWater (puff, P_PointInSector(hitx, hity), hitx, hity, hitz);
			}
		}
		else
		{
			bool bloodsplatter = (t1->flags5 & MF5_BLOODSPLATTER) ||
									(t1->player != NULL &&	t1->player->ReadyWeapon != NULL &&
										(t1->player->ReadyWeapon->WeaponFlags & WIF_AXEBLOOD));

			bool axeBlood = (t1->player != NULL &&
				t1->player->ReadyWeapon != NULL &&
				(t1->player->ReadyWeapon->WeaponFlags & WIF_AXEBLOOD));

			// Hit a thing, so it could be either a puff or blood
			hitx = t1->x + FixedMul (vx, trace.Distance);
			hity = t1->y + FixedMul (vy, trace.Distance);
			hitz = shootz + FixedMul (vz, trace.Distance);

			// Spawn bullet puffs or blood spots, depending on target type.
			AActor *puffDefaults = GetDefaultByType (pufftype);
			if ((puffDefaults->flags3 & MF3_PUFFONACTORS) ||
				(trace.Actor->flags & MF_NOBLOOD) ||
				(trace.Actor->flags2 & (MF2_INVULNERABLE|MF2_DORMANT)))
			{
				puff = P_SpawnPuff (t1, pufftype, hitx, hity, hitz, angle - ANG180, 2, flags|PF_HITTHING);
			}
			if (!(GetDefaultByType(pufftype)->flags3&MF3_BLOODLESSIMPACT))
			{
				if (!bloodsplatter && !axeBlood &&
					!(trace.Actor->flags & MF_NOBLOOD) &&
					!(trace.Actor->flags2 & (MF2_INVULNERABLE|MF2_DORMANT)))
				{
					P_SpawnBlood (hitx, hity, hitz, angle - ANG180, damage, trace.Actor);
				}
	
				if (damage)
				{
					if (bloodsplatter || axeBlood)
					{
						if (!(trace.Actor->flags&MF_NOBLOOD) &&
							!(trace.Actor->flags2&(MF2_INVULNERABLE|MF2_DORMANT)))
						{
							if (axeBlood)
							{
								P_BloodSplatter2 (hitx, hity, hitz, trace.Actor);
							}
							if (pr_lineattack() < 192)
							{
								P_BloodSplatter (hitx, hity, hitz, trace.Actor);
							}
						}
					}
					// [RH] Stick blood to walls
					P_TraceBleed (damage, trace.X, trace.Y, trace.Z,
						trace.Actor, srcangle, srcpitch);
				}
			}
			// [GZ] If MF6_FORCEPAIN is set, we need to call P_DamageMobj even if damage is 0!
			// Note: The puff may not yet be spawned here so we must check the class defaults, not the actor.
			if (damage || (puffDefaults->flags6 & MF6_FORCEPAIN))
			{
				int flags = DMG_INFLICTOR_IS_PUFF;
				// Allow MF5_PIERCEARMOR on a weapon as well.
				if (t1->player != NULL && t1->player->ReadyWeapon != NULL &&
					t1->player->ReadyWeapon->flags5 & MF5_PIERCEARMOR)
				{
					flags |= DMG_NO_ARMOR;
				}
			
				if (puff == NULL)
				{ 
					// Since the puff is the damage inflictor we need it here 
					// regardless of whether it is displayed or not.
					puff = P_SpawnPuff (t1, pufftype, hitx, hity, hitz, angle - ANG180, 2, flags|PF_HITTHING|PF_TEMPORARY);
					killPuff = true;
				}
				P_DamageMobj (trace.Actor, puff ? puff : t1, t1, damage, damageType, flags);
			}
		}
		if (trace.CrossedWater)
		{

			if (puff == NULL)
			{ // Spawn puff just to get a mass for the splash
				puff = P_SpawnPuff (t1, pufftype, hitx, hity, hitz, angle - ANG180, 2, flags|PF_HITTHING|PF_TEMPORARY);
				killPuff = true;
			}
			SpawnDeepSplash (t1, trace, puff, vx, vy, vz, shootz);
		}
	}
	if (killPuff && puff != NULL)
	{
		puff->Destroy();
		puff = NULL;
	}
	return puff;
}

AActor *P_LineAttack (AActor *t1, angle_t angle, fixed_t distance,
				   int pitch, int damage, FName damageType, FName pufftype, bool ismeleeattack)
{
	const PClass * type = PClass::FindClass(pufftype);
	if (type == NULL)
	{
		Printf("Attempt to spawn unknown actor type '%s'\n", pufftype.GetChars());
	}
	else
	{
		return P_LineAttack(t1, angle, distance, pitch, damage, damageType, type, ismeleeattack);
	}
	return NULL;
}

void P_TraceBleed (int damage, fixed_t x, fixed_t y, fixed_t z, AActor *actor, angle_t angle, int pitch)
{
	if (!cl_bloodsplats)
		return;

	const char *bloodType = "BloodSplat";
	int count;
	int noise;

	if ((actor->flags & MF_NOBLOOD) ||
		(actor->flags5 & MF5_NOBLOODDECALS) ||
		(actor->flags2 & (MF2_INVULNERABLE|MF2_DORMANT)) ||
		(actor->player && actor->player->cheats & CF_GODMODE))
	{
		return;
	}
	if (damage < 15)
	{	// For low damages, there is a chance to not spray blood at all
		if (damage <= 10)
		{
			if (pr_tracebleed() < 160)
			{
				return;
			}
		}
		count = 1;
		noise = 18;
	}
	else if (damage < 25)
	{
		count = 2;
		noise = 19;
	}
	else
	{	// For high damages, there is a chance to spray just one big glob of blood
		if (pr_tracebleed() < 24)
		{
			bloodType = "BloodSmear";
			count = 1;
			noise = 20;
		}
		else
		{
			count = 3;
			noise = 20;
		}
	}

	for (; count; --count)
	{
		FTraceResults bleedtrace;

		angle_t bleedang = (angle + ((pr_tracebleed()-128) << noise)) >> ANGLETOFINESHIFT;
		angle_t bleedpitch = (angle_t)(pitch + ((pr_tracebleed()-128) << noise)) >> ANGLETOFINESHIFT;
		fixed_t vx = FixedMul (finecosine[bleedpitch], finecosine[bleedang]);
		fixed_t vy = FixedMul (finecosine[bleedpitch], finesine[bleedang]);
		fixed_t vz = -finesine[bleedpitch];

		if (Trace (x, y, z, actor->Sector,
					vx, vy, vz, 172*FRACUNIT, 0, ML_BLOCKEVERYTHING, actor,
					bleedtrace, TRACE_NoSky))
		{
			if (bleedtrace.HitType == TRACE_HitWall)
			{
				PalEntry bloodcolor = (PalEntry)actor->GetClass()->Meta.GetMetaInt(AMETA_BloodColor);
				if (bloodcolor != 0)
				{
					bloodcolor.r>>=1;	// the full color is too bright for blood decals
					bloodcolor.g>>=1;
					bloodcolor.b>>=1;
					bloodcolor.a=1;
				}

				DImpactDecal::StaticCreate (bloodType,
					bleedtrace.X, bleedtrace.Y, bleedtrace.Z,
					bleedtrace.Line->sidedef[bleedtrace.Side],
					bleedtrace.ffloor,
					bloodcolor);
			}
		}
	}
}

void P_TraceBleed (int damage, AActor *target, angle_t angle, int pitch)
{
	P_TraceBleed (damage, target->x, target->y, target->z + target->height/2,
		target, angle, pitch);
}

void P_TraceBleed (int damage, AActor *target, AActor *missile)
{
	int pitch;

	if (target == NULL || missile->flags3 & MF3_BLOODLESSIMPACT)
	{
		return;
	}

	if (missile->velz != 0)
	{
		double aim;

		aim = atan ((double)missile->velz / (double)P_AproxDistance (missile->x - target->x, missile->y - target->y));
		pitch = -(int)(aim * ANGLE_180/PI);
	}
	else
	{
		pitch = 0;
	}
	P_TraceBleed (damage, target->x, target->y, target->z + target->height/2,
		target, R_PointToAngle2 (missile->x, missile->y, target->x, target->y),
		pitch);
}

void P_TraceBleed (int damage, AActor *target)
{
	if (target != NULL)
	{
		fixed_t one = pr_tracebleed() << 24;
		fixed_t two = (pr_tracebleed()-128) << 16;

		P_TraceBleed (damage, target->x, target->y, target->z + target->height/2,
			target, one, two);
	}
}

//
// [RH] Rail gun stuffage
//
struct SRailHit
{
	AActor *HitActor;
	fixed_t Distance;
};
static TArray<SRailHit> RailHits (16);

static bool ProcessRailHit (FTraceResults &res)
{
	if (res.HitType != TRACE_HitActor)
	{
		return false;
	}

	// Invulnerable things completely block the shot
	if (res.Actor->flags2 & MF2_INVULNERABLE)
	{
		return false;
	}

	// Save this thing for damaging later, and continue the trace
	SRailHit newhit;
	newhit.HitActor = res.Actor;
	newhit.Distance = res.Distance - 10*FRACUNIT;	// put blood in front
	RailHits.Push (newhit);

	return true;
}

static bool ProcessNoPierceRailHit (FTraceResults &res)
{
	if (res.HitType != TRACE_HitActor)
	{
		return false;
	}

	// Invulnerable things completely block the shot
	if (res.Actor->flags2 & MF2_INVULNERABLE)
	{
		return false;
	}

	// Only process the first hit
	SRailHit newhit;
	newhit.HitActor = res.Actor;
	newhit.Distance = res.Distance - 10*FRACUNIT;	// put blood in front
	RailHits.Push (newhit);

	return false;
}

void P_RailAttack (AActor *source, int damage, int offset, int color1, int color2, float maxdiff, bool silent, const PClass *puffclass, bool pierce)
{
	fixed_t vx, vy, vz;
	angle_t angle, pitch;
	fixed_t x1, y1;
	FVector3 start, end;
	FTraceResults trace;
	fixed_t shootz;

	if (puffclass == NULL) puffclass = PClass::FindClass(NAME_BulletPuff);

	pitch = (angle_t)(-source->pitch) >> ANGLETOFINESHIFT;
	angle = source->angle >> ANGLETOFINESHIFT;

	vx = FixedMul (finecosine[pitch], finecosine[angle]);
	vy = FixedMul (finecosine[pitch], finesine[angle]);
	vz = finesine[pitch];

	x1 = source->x;
	y1 = source->y;

	shootz = source->z - source->floorclip + (source->height >> 1);

	if (source->player != NULL)
	{
		shootz += FixedMul (source->player->mo->AttackZOffset, source->player->crouchfactor);
	}
	else
	{
		shootz += 8*FRACUNIT;
	}

	angle = (source->angle - ANG90) >> ANGLETOFINESHIFT;
	x1 += offset*finecosine[angle];
	y1 += offset*finesine[angle];

	RailHits.Clear ();
	start.X = FIXED2FLOAT(x1);
	start.Y = FIXED2FLOAT(y1);
	start.Z = FIXED2FLOAT(shootz);

	if (pierce)
	{
		Trace (x1, y1, shootz, source->Sector, vx, vy, vz,
			8192*FRACUNIT, MF_SHOOTABLE, ML_BLOCKEVERYTHING, source, trace,
			TRACE_PCross|TRACE_Impact, ProcessRailHit);
	}
	else
	{
		Trace (x1, y1, shootz, source->Sector, vx, vy, vz,
			8192*FRACUNIT, MF_SHOOTABLE, ML_BLOCKEVERYTHING, source, trace,
			TRACE_PCross|TRACE_Impact, ProcessNoPierceRailHit);
	}

	// Hurt anything the trace hit
	unsigned int i;
	AActor *puffDefaults = puffclass == NULL? NULL : GetDefaultByType (puffclass);
	FName damagetype = (puffDefaults == NULL || puffDefaults->DamageType == NAME_None) ? FName(NAME_Railgun) : puffDefaults->DamageType;

	// used as damage inflictor
	AActor *thepuff = NULL;
	
	if (puffclass != NULL) thepuff = Spawn (puffclass, source->x, source->y, source->z, ALLOW_REPLACE);

	for (i = 0; i < RailHits.Size (); i++)
	{
		fixed_t x, y, z;

		x = x1 + FixedMul (RailHits[i].Distance, vx);
		y = y1 + FixedMul (RailHits[i].Distance, vy);
		z = shootz + FixedMul (RailHits[i].Distance, vz);

		if ((RailHits[i].HitActor->flags & MF_NOBLOOD) ||
			(RailHits[i].HitActor->flags2 & (MF2_DORMANT|MF2_INVULNERABLE)))
		{
			if (puffclass != NULL) P_SpawnPuff (source, puffclass, x, y, z, source->angle - ANG90, 1, PF_HITTHING);
		}
		else
		{
			P_SpawnBlood (x, y, z, source->angle - ANG180, damage, RailHits[i].HitActor);
			P_TraceBleed (damage, x, y, z, RailHits[i].HitActor, source->angle, pitch);
		}
		P_DamageMobj (RailHits[i].HitActor, thepuff? thepuff:source, source, damage, damagetype, DMG_INFLICTOR_IS_PUFF);
	}

	// Spawn a decal or puff at the point where the trace ended.
	if (trace.HitType == TRACE_HitWall)
	{
		SpawnShootDecal (source, trace);
	}
	if (trace.HitType == TRACE_HitFloor &&
		trace.CrossedWater == NULL &&
		trace.Sector->heightsec == NULL)
	{
		if (thepuff != NULL)
		{
			thepuff->SetOrigin(trace.X, trace.Y, trace.Z);
			P_HitWater (thepuff, trace.Sector);
		}
	}
	if (trace.CrossedWater)
	{
		if (thepuff != NULL)
		{
			SpawnDeepSplash (source, trace, thepuff, vx, vy, vz, shootz);
		}
	}
	thepuff->Destroy ();

	// Draw the slug's trail.
	end.X = FIXED2FLOAT(trace.X);
	end.Y = FIXED2FLOAT(trace.Y);
	end.Z = FIXED2FLOAT(trace.Z);
	P_DrawRailTrail (source, start, end, color1, color2, maxdiff, silent);
}

//
// [RH] P_AimCamera
//
CVAR (Float, chase_height, -8.f, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
CVAR (Float, chase_dist, 90.f, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)

void P_AimCamera (AActor *t1, fixed_t &CameraX, fixed_t &CameraY, fixed_t &CameraZ, sector_t *&CameraSector)
{
	fixed_t distance = (fixed_t)(chase_dist * FRACUNIT);
	angle_t angle = (t1->angle - ANG180) >> ANGLETOFINESHIFT;
	angle_t pitch = (angle_t)(t1->pitch) >> ANGLETOFINESHIFT;
	FTraceResults trace;
	fixed_t vx, vy, vz, sz;

	vx = FixedMul (finecosine[pitch], finecosine[angle]);
	vy = FixedMul (finecosine[pitch], finesine[angle]);
	vz = finesine[pitch];

	sz = t1->z - t1->floorclip + t1->height + (fixed_t)(chase_height * FRACUNIT);

	if (Trace (t1->x, t1->y, sz, t1->Sector,
		vx, vy, vz, distance, 0, 0, NULL, trace) &&
		trace.Distance > 10*FRACUNIT)
	{
		// Position camera slightly in front of hit thing
		fixed_t dist = trace.Distance - 5*FRACUNIT;
		CameraX = t1->x + FixedMul (vx, dist);
		CameraY = t1->y + FixedMul (vy, dist);
		CameraZ = sz + FixedMul (vz, dist);
	}
	else
	{
		CameraX = trace.X;
		CameraY = trace.Y;
		CameraZ = trace.Z;
	}
	CameraSector = trace.Sector;
}


//
// USE LINES
//

bool P_UseTraverse(AActor *usething, fixed_t endx, fixed_t endy, bool &foundline)
{
	FPathTraverse it(usething->x, usething->y, endx, endy, PT_ADDLINES|PT_ADDTHINGS);
	intercept_t *in;

	while ((in = it.Next()))
	{
		// [RH] Check for things to talk with or use a puzzle item on
		if (!in->isaline)
		{
			if (usething==in->d.thing) continue;
			// Check thing

			// Check for puzzle item use or USESPECIAL flag
			// Extended to use the same activationtype mechanism as BUMPSPECIAL does
			if (in->d.thing->flags5 & MF5_USESPECIAL || in->d.thing->special == UsePuzzleItem)
			{	// Target switching mechanism
				if (in->d.thing->activationtype & THINGSPEC_ThingTargets) in->d.thing->target = usething;
				if (in->d.thing->activationtype & THINGSPEC_TriggerTargets) usething->target = in->d.thing;
				// Run the special
				if (LineSpecials[in->d.thing->special] (NULL, // Who triggers?
					((in->d.thing->activationtype & THINGSPEC_ThingActs) ? in->d.thing : usething), false, 
					in->d.thing->args[0], in->d.thing->args[1], in->d.thing->args[2],
					in->d.thing->args[3], in->d.thing->args[4]))
				{
					if (in->d.thing->activationtype & THINGSPEC_ClearSpecial) in->d.thing->special = 0;
					return true;
				}
			}
			// Dead things can't talk.
			if (in->d.thing->health <= 0)
			{
				continue;
			}
			// Fighting things don't talk either.
			if (in->d.thing->flags4 & MF4_INCOMBAT)
			{
				continue;
			}
			if (in->d.thing->Conversation != NULL)
			{
				// Give the NPC a chance to play a brief animation
				in->d.thing->ConversationAnimation (0);
				P_StartConversation (in->d.thing, usething, true, true);
				return true;
			}
			continue;
		}

		FLineOpening open;
		// [RH] The range passed to P_PathTraverse was doubled so that it could
		// find things up to 128 units away (for Strife), but it should still reject
		// lines further than 64 units away.
		if (in->frac > FRACUNIT/2)
		{
			// don't pass usething here. It will not do what might be expected!
			P_LineOpening (open, NULL, in->d.line, it.Trace().x + FixedMul (it.Trace().dx, in->frac),
				it.Trace().y + FixedMul (it.Trace().dy, in->frac));
			if (open.range <= 0) return false;
			else continue;
		}
		if (in->d.line->special == 0 || !(in->d.line->activation & (SPAC_Use|SPAC_UseThrough)))
		{
	blocked:
			if (in->d.line->flags & (ML_BLOCKEVERYTHING|ML_BLOCKUSE))
			{
				open.range = 0;
			}
			else
			{
				P_LineOpening (open, NULL, in->d.line, it.Trace().x + FixedMul (it.Trace().dx, in->frac),
					it.Trace().y + FixedMul (it.Trace().dy, in->frac));
			}
			if (open.range <= 0 ||
				(in->d.line->special != 0 && (i_compatflags & COMPATF_USEBLOCKING)))
			{
				// [RH] Give sector a chance to intercept the use

				sector_t * sec;

				sec = usething->Sector;

				if (sec->SecActTarget && sec->SecActTarget->TriggerAction (usething, SECSPAC_Use))
				{
					return true;
				}

				sec = P_PointOnLineSide(usething->x, usething->y, in->d.line) == 0?
					in->d.line->frontsector : in->d.line->backsector;

				if (sec != NULL && sec->SecActTarget &&
					sec->SecActTarget->TriggerAction (usething, SECSPAC_UseWall))
				{
					return true;
				}

				if (usething->player)
				{
					S_Sound (usething, CHAN_VOICE, "*usefail", 1, ATTN_IDLE);
				}
				return true;		// can't use through a wall
			}
			foundline = true;
			continue;			// not a special line, but keep checking
		}
			
		if (P_PointOnLineSide (usething->x, usething->y, in->d.line) == 1)
			// [RH] continue traversal for two-sided lines
			//return in->d.line->backsector != NULL;		// don't use back side
			goto blocked;	// do a proper check for back sides of triggers
			
		P_ActivateLine (in->d.line, usething, 0, SPAC_Use);

		//WAS can't use more than one special line in a row
		//jff 3/21/98 NOW multiple use allowed with enabling line flag
		//[RH] And now I've changed it again. If the line is of type
		//	   SPAC_USE, then it eats the use. Everything else passes
		//	   it through, including SPAC_USETHROUGH.
		if (i_compatflags & COMPATF_USEBLOCKING)
		{
			if (in->d.line->activation & SPAC_UseThrough) continue;
			else return true;
		}
		else
		{
			if (!(in->d.line->activation & SPAC_Use)) continue;
			else return true;
		}
	}
	return false;
}

// Returns false if a "oof" sound should be made because of a blocking
// linedef. Makes 2s middles which are impassable, as well as 2s uppers
// and lowers which block the player, cause the sound effect when the
// player tries to activate them. Specials are excluded, although it is
// assumed that all special linedefs within reach have been considered
// and rejected already (see P_UseLines).
//
// by Lee Killough
//

bool P_NoWayTraverse (AActor *usething, fixed_t endx, fixed_t endy)
{
	FPathTraverse it(usething->x, usething->y, endx, endy, PT_ADDLINES);
	intercept_t *in;

	while ((in = it.Next()))
	{
		line_t *ld = in->d.line;
		FLineOpening open;

		// [GrafZahl] de-obfuscated. Was I the only one who was unable to makes sense out of
		// this convoluted mess?
		if (ld->special) continue;
		if (ld->flags&(ML_BLOCKING|ML_BLOCKEVERYTHING|ML_BLOCK_PLAYERS)) return true;
		P_LineOpening(open, NULL, ld, it.Trace().x+FixedMul(it.Trace().dx, in->frac),
									  it.Trace().y+FixedMul(it.Trace().dy, in->frac));
		if (open.range <= 0 ||
			open.bottom > usething->z + usething->MaxStepHeight ||
			open.top < usething->z + usething->height) return true;
	}
	return false;
}

/*
================
=
= P_UseLines
=
= Looks for special lines in front of the player to activate
================
*/

void P_UseLines (player_t *player)
{
	angle_t angle;
	fixed_t x2, y2;
	bool foundline;

	foundline = false;

	angle = player->mo->angle >> ANGLETOFINESHIFT;
	x2 = player->mo->x + (USERANGE>>FRACBITS)*finecosine[angle]*2;
	y2 = player->mo->y + (USERANGE>>FRACBITS)*finesine[angle]*2;

	// old code:
	//
	// P_PathTraverse ( x1, y1, x2, y2, PT_ADDLINES, PTR_UseTraverse );
	//
	// This added test makes the "oof" sound work on 2s lines -- killough:

	if (!P_UseTraverse (player->mo, x2, y2, foundline))
	{ // [RH] Give sector a chance to eat the use
		sector_t *sec = player->mo->Sector;
		int spac = SECSPAC_Use;
		if (foundline) spac |= SECSPAC_UseWall;
		if ((!sec->SecActTarget || !sec->SecActTarget->TriggerAction (player->mo, spac)) &&
			P_NoWayTraverse (player->mo, x2, y2))
		{
			S_Sound (player->mo, CHAN_VOICE, "*usefail", 1, ATTN_IDLE);
		}
	}
}

//==========================================================================
//
// P_UsePuzzleItem
//
// Returns true if the puzzle item was used on a line or a thing.
//
//==========================================================================

bool P_UsePuzzleItem (AActor *PuzzleItemUser, int PuzzleItemType)
{
	int angle;
	fixed_t x1, y1, x2, y2;

	angle = PuzzleItemUser->angle>>ANGLETOFINESHIFT;
	x1 = PuzzleItemUser->x;
	y1 = PuzzleItemUser->y;
	x2 = x1+(USERANGE>>FRACBITS)*finecosine[angle];
	y2 = y1+(USERANGE>>FRACBITS)*finesine[angle];

	FPathTraverse it(x1, y1, x2, y2, PT_ADDLINES|PT_ADDTHINGS);
	intercept_t *in;

	while ((in = it.Next()))
	{
		AActor *mobj;
		FLineOpening open;

		if (in->isaline)
		{ // Check line
			if (in->d.line->special != UsePuzzleItem)
			{
				P_LineOpening (open, NULL, in->d.line, it.Trace().x + FixedMul (it.Trace().dx, in->frac),
					it.Trace().y + FixedMul (it.Trace().dy, in->frac));
				if (open.range <= 0)
				{
					return false; // can't use through a wall
				}
				continue;
			}
			if (P_PointOnLineSide (PuzzleItemUser->x, PuzzleItemUser->y, in->d.line) == 1)
			{ // Don't use back sides
				return false;
			}
			if (PuzzleItemType != in->d.line->args[0])
			{ // Item type doesn't match
				return false;
			}
			P_StartScript (PuzzleItemUser, in->d.line, in->d.line->args[1], NULL, 0,
				in->d.line->args[2], in->d.line->args[3], in->d.line->args[4], true, false);
			in->d.line->special = 0;
			return true;
		}
		// Check thing
		mobj = in->d.thing;
		if (mobj->special != UsePuzzleItem)
		{ // Wrong special
			continue;
		}
		if (PuzzleItemType != mobj->args[0])
		{ // Item type doesn't match
			continue;
		}
		P_StartScript (PuzzleItemUser, NULL, mobj->args[1], NULL, 0,
			mobj->args[2], mobj->args[3], mobj->args[4], true, false);
		mobj->special = 0;
		return true;
	}
	return false;
}

//
// RADIUS ATTACK
//

// [RH] Damage scale to apply to thing that shot the missile.
static float selfthrustscale;

CUSTOM_CVAR (Float, splashfactor, 1.f, CVAR_SERVERINFO)
{
	if (self <= 0.f)
		self = 1.f;
	else
		selfthrustscale = 1.f / self;
}

//
// P_RadiusAttack
// Source is the creature that caused the explosion at spot.
//
void P_RadiusAttack (AActor *bombspot, AActor *bombsource, int bombdamage, int bombdistance, FName bombmod,
	bool DamageSource, bool bombdodamage, int fulldamagedistance)
{
	if (bombdistance <= 0)
		return;
	fulldamagedistance = clamp<int>(fulldamagedistance, 0, bombdistance-1);

	float bombdistancefloat = 1.f / (float)(bombdistance - fulldamagedistance);
	float bombdamagefloat = (float)bombdamage;

	FVector3 bombvec(FIXED2FLOAT(bombspot->x), FIXED2FLOAT(bombspot->y), FIXED2FLOAT(bombspot->z));

	FBlockThingsIterator it(FBoundingBox(bombspot->x, bombspot->y, bombdistance<<FRACBITS));
	AActor *thing;

	while ((thing = it.Next()))
	{
		// Vulnerable actors can be damaged by radius attacks even if not shootable
		// Used to emulate MBF's vulnerability of non-missile bouncers to explosions.
		if (!((thing->flags & MF_SHOOTABLE) || (thing->flags6 & MF6_VULNERABLE)))
			continue;

		// Boss spider and cyborg and Heretic's ep >= 2 bosses
		// take no damage from concussion.
		if (thing->flags3 & MF3_NORADIUSDMG && !(bombspot->flags4 & MF4_FORCERADIUSDMG))
			continue;

		if (!DamageSource && thing == bombsource)
		{ // don't damage the source of the explosion
			continue;
		}

		// a much needed option: monsters that fire explosive projectiles cannot 
		// be hurt by projectiles fired by a monster of the same type.
		// Controlled by the DONTHARMCLASS and DONTHARMSPECIES flags.
		if ((bombsource && !thing->player) // code common to both checks
		&& ( // Class check first
			((bombsource->flags4 & MF4_DONTHARMCLASS) && (thing->GetClass() == bombsource->GetClass()))
			|| // Nigh-identical species check second
			((bombsource->flags6 & MF6_DONTHARMSPECIES) && (thing->GetSpecies() == bombsource->GetSpecies()))
			)
		)	continue;

		// Barrels always use the original code, since this makes
		// them far too "active." BossBrains also use the old code
		// because some user levels require they have a height of 16,
		// which can make them near impossible to hit with the new code.
		if (!bombdodamage || !((bombspot->flags5 | thing->flags5) & MF5_OLDRADIUSDMG))
		{
			// [RH] New code. The bounding box only covers the
			// height of the thing and not the height of the map.
			float points;
			float len;
			fixed_t dx, dy;
			float boxradius;

			dx = abs (thing->x - bombspot->x);
			dy = abs (thing->y - bombspot->y);
			boxradius = float (thing->radius);

			// The damage pattern is square, not circular.
			len = float (dx > dy ? dx : dy);

			if (bombspot->z < thing->z || bombspot->z >= thing->z + thing->height)
			{
				float dz;

				if (bombspot->z > thing->z)
				{
					dz = float (bombspot->z - thing->z - thing->height);
				}
				else
				{
					dz = float (thing->z - bombspot->z);
				}
				if (len <= boxradius)
				{
					len = dz;
				}
				else
				{
					len -= boxradius;
					len = sqrtf (len*len + dz*dz);
				}
			}
			else
			{
				len -= boxradius;
				if (len < 0.f)
					len = 0.f;
			}
			len /= FRACUNIT;
			len = clamp<float>(len - (float)fulldamagedistance, 0, len);
			points = bombdamagefloat * (1.f - len * bombdistancefloat);
			if (thing == bombsource)
			{
				points = points * splashfactor;
			}
			points *= thing->GetClass()->Meta.GetMetaFixed(AMETA_RDFactor, FRACUNIT)/(float)FRACUNIT;

			if (points > 0.f && P_CheckSight (thing, bombspot, 1))
			{ // OK to damage; target is in direct path
				float velz;
				float thrust;
				int damage = (int)points;

				if (bombdodamage) P_DamageMobj (thing, bombspot, bombsource, damage, bombmod);
				else if (thing->player == NULL) thing->flags2 |= MF2_BLASTED;

				if (!(thing->flags & MF_ICECORPSE))
				{
					if (bombdodamage && !(bombspot->flags3 & MF3_BLOODLESSIMPACT)) P_TraceBleed (damage, thing, bombspot);

					if (!bombdodamage || !(bombspot->flags2 & MF2_NODMGTHRUST))
					{
						if (bombsource == NULL  || !(bombsource->flags2 & MF2_NODMGTHRUST))
						{
							thrust = points * 0.5f / (float)thing->Mass;
							if (bombsource == thing)
							{
								thrust *= selfthrustscale;
							}
							velz = (float)(thing->z + (thing->height>>1) - bombspot->z) * thrust;
							if (bombsource != thing)
							{
								velz *= 0.5f;
							}
							else
							{
								velz *= 0.8f;
							}
							angle_t ang = R_PointToAngle2 (bombspot->x, bombspot->y, thing->x, thing->y) >> ANGLETOFINESHIFT;
							thing->velx += fixed_t (finecosine[ang] * thrust);
							thing->vely += fixed_t (finesine[ang] * thrust);
							if (bombdodamage)
								thing->velz += (fixed_t)velz;	// this really doesn't work well
						}
					}
				}
			}
		}
		else
		{
			// [RH] Old code just for barrels
			fixed_t dx, dy, dist;

			dx = abs (thing->x - bombspot->x);
			dy = abs (thing->y - bombspot->y);

			dist = dx>dy ? dx : dy;
			dist = (dist - thing->radius) >> FRACBITS;

			if (dist < 0)
				dist = 0;

			if (dist >= bombdistance)
				continue;  // out of range

			if (P_CheckSight (thing, bombspot, 1))
			{ // OK to damage; target is in direct path
				dist = clamp<int>(dist - fulldamagedistance, 0, dist);
				int damage = Scale (bombdamage, bombdistance-dist, bombdistance-fulldamagedistance);
				damage = (int)((float)damage * splashfactor);

				damage = Scale(damage, thing->GetClass()->Meta.GetMetaFixed(AMETA_RDFactor, FRACUNIT), FRACUNIT);
				if (damage > 0)
				{
					P_DamageMobj (thing, bombspot, bombsource, damage, bombmod);
					P_TraceBleed (damage, thing, bombspot);
				}
			}
		}
	}
}

//
// SECTOR HEIGHT CHANGING
// After modifying a sector's floor or ceiling height,
// call this routine to adjust the positions
// of all things that touch the sector.
//
// If anything doesn't fit anymore, true will be returned.
//
// [RH] If crushchange is non-negative, they will take the
//		specified amount of damage as they are being crushed.
//		If crushchange is negative, you should set the sector
//		height back the way it was and call P_ChangeSector()
//		again to undo the changes.
//		Note that this is very different from the original
//		true/false usage of crushchange! If you want regular
//		DOOM crushing behavior set crushchange to 10 or -1
//		if no crushing is desired.
//

struct FChangePosition
{
	sector_t *sector;
	int moveamt;
	int crushchange;
	bool nofit;
	bool movemidtex;
};

TArray<AActor *> intersectors;

EXTERN_CVAR (Int, cl_bloodtype)

//=============================================================================
//
// P_AdjustFloorCeil
//
//=============================================================================

bool P_AdjustFloorCeil (AActor *thing, FChangePosition *cpos)
{
	int flags2 = thing->flags2 & MF2_PASSMOBJ;
	FCheckPosition tm;

	if (cpos->movemidtex)
	{
		// From Eternity:
		// ALL things must be treated as PASSMOBJ when moving
		// 3DMidTex lines, otherwise you get stuck in them.
		thing->flags2 |= MF2_PASSMOBJ;
	}

	bool isgood = P_CheckPosition (thing, thing->x, thing->y, tm);
	thing->floorz = tm.floorz;
	thing->ceilingz = tm.ceilingz;
	thing->dropoffz = tm.dropoffz;		// killough 11/98: remember dropoffs
	thing->floorpic = tm.floorpic;
	thing->floorsector = tm.floorsector;
	thing->ceilingpic = tm.ceilingpic;
	thing->ceilingsector = tm.ceilingsector;

	// restore the PASSMOBJ flag but leave the other flags alone.
	thing->flags2 = (thing->flags2 & ~MF2_PASSMOBJ) | flags2;

	return isgood;
}

//=============================================================================
//
// P_FindAboveIntersectors
//
//=============================================================================

void P_FindAboveIntersectors (AActor *actor)
{
	if (actor->flags & MF_NOCLIP)
		return;

	if (!(actor->flags & MF_SOLID))
		return;

	AActor *thing;
	FBlockThingsIterator it(FBoundingBox(actor->x, actor->y, actor->radius));
	while ((thing = it.Next()))
	{
		if (!thing->intersects(actor))
		{
			continue;
		}
		if (!(thing->flags & MF_SOLID))
		{ // Can't hit thing
			continue;
		}
		if (thing->flags & (MF_CORPSE|MF_SPECIAL))
		{ // [RH] Corpses and specials don't block moves
			continue;
		}
		if (thing == actor)
		{ // Don't clip against self
			continue;
		}
		if (thing->z >= actor->z &&
			thing->z <= actor->z + actor->height)
		{ // Thing intersects above the base
			intersectors.Push (thing);
		}
	}
}

//=============================================================================
//
// P_FindBelowIntersectors
//
//=============================================================================

void P_FindBelowIntersectors (AActor *actor)
{
	if (actor->flags & MF_NOCLIP)
		return;

	if (!(actor->flags & MF_SOLID))
		return;

	AActor *thing;
	FBlockThingsIterator it(FBoundingBox(actor->x, actor->y, actor->radius));
	while ((thing = it.Next()))
	{
		if (!thing->intersects(actor))
		{
			continue;
		}
		if (!(thing->flags & MF_SOLID))
		{ // Can't hit thing
			continue;
		}
		if (thing->flags & (MF_CORPSE|MF_SPECIAL))
		{ // [RH] Corpses and specials don't block moves
			continue;
		}
		if (thing == actor)
		{ // Don't clip against self
			continue;
		}
		if (thing->z + thing->height <= actor->z + actor->height &&
			thing->z + thing->height > actor->z)
		{ // Thing intersects below the base
			intersectors.Push (thing);
		}
	}
}

//=============================================================================
//
// P_DoCrunch
//
//=============================================================================

void P_DoCrunch (AActor *thing, FChangePosition *cpos)
{
	if (!(thing && thing->Grind(true) && cpos)) return;
	cpos->nofit = true;

	if ((cpos->crushchange > 0) && !(level.maptime & 3))
	{
		P_DamageMobj (thing, NULL, NULL, cpos->crushchange, NAME_Crush);

		// spray blood in a random direction
		if ((!(thing->flags&MF_NOBLOOD)) &&
			(!(thing->flags2&(MF2_INVULNERABLE|MF2_DORMANT))))
		{
			PalEntry bloodcolor = (PalEntry)thing->GetClass()->Meta.GetMetaInt(AMETA_BloodColor);
			const PClass *bloodcls = PClass::FindClass((ENamedName)thing->GetClass()->Meta.GetMetaInt(AMETA_BloodType, NAME_Blood));

			P_TraceBleed (cpos->crushchange, thing);
			if (cl_bloodtype <= 1 && bloodcls != NULL)
			{
				AActor *mo;

				mo = Spawn (bloodcls, thing->x, thing->y,
					thing->z + thing->height/2, ALLOW_REPLACE);

				mo->velx = pr_crunch.Random2 () << 12;
				mo->vely = pr_crunch.Random2 () << 12;
				if (bloodcolor != 0 && !(mo->flags2 & MF2_DONTTRANSLATE))
				{
					mo->Translation = TRANSLATION(TRANSLATION_Blood, bloodcolor.a);
				}
			}
			if (cl_bloodtype >= 1)
			{
				angle_t an;

				an = (M_Random () - 128) << 24;
				P_DrawSplash2 (32, thing->x, thing->y,
							   thing->z + thing->height/2, an, 2, bloodcolor);
			}
		}
	}

	// keep checking (crush other things)
	return;
}

//=============================================================================
//
// P_PushUp
//
// Returns 0 if thing fits, 1 if ceiling got in the way, or 2 if something
// above it didn't fit.
//=============================================================================

int P_PushUp (AActor *thing, FChangePosition *cpos)
{
	unsigned int firstintersect = intersectors.Size ();
	unsigned int lastintersect;
	int mymass = thing->Mass;

	if (thing->z + thing->height > thing->ceilingz)
	{
		return 1;
	}
	P_FindAboveIntersectors (thing);
	lastintersect = intersectors.Size ();
	for (; firstintersect < lastintersect; firstintersect++)
	{
		AActor *intersect = intersectors[firstintersect];
		if (!(intersect->flags2 & MF2_PASSMOBJ) ||
			(!(intersect->flags3 & MF3_ISMONSTER) &&
			 intersect->Mass > mymass))
		{ // Can't push things more massive than ourself
			return 2;
		}
		fixed_t oldz = intersect->z;
		P_AdjustFloorCeil (intersect, cpos);
		intersect->z = thing->z + thing->height + 1;
		if (P_PushUp (intersect, cpos))
		{ // Move blocked
			P_DoCrunch (intersect, cpos);
			intersect->z = oldz;
			return 2;
		}
	}
	return 0;
}

//=============================================================================
//
// P_PushDown
//
// Returns 0 if thing fits, 1 if floor got in the way, or 2 if something
// below it didn't fit.
//=============================================================================

int P_PushDown (AActor *thing, FChangePosition *cpos)
{
	unsigned int firstintersect = intersectors.Size ();
	unsigned int lastintersect;
	int mymass = thing->Mass;

	if (thing->z <= thing->floorz)
	{
		return 1;
	}
	P_FindBelowIntersectors (thing);
	lastintersect = intersectors.Size ();
	for (; firstintersect < lastintersect; firstintersect++)
	{
		AActor *intersect = intersectors[firstintersect];
		if (!(intersect->flags2 & MF2_PASSMOBJ) ||
			(!(intersect->flags3 & MF3_ISMONSTER) &&
			 intersect->Mass > mymass))
		{ // Can't push things more massive than ourself
			return 2;
		}
		fixed_t oldz = intersect->z;
		P_AdjustFloorCeil (intersect, cpos);
		if (oldz > thing->z - intersect->height)
		{ // Only push things down, not up.
			intersect->z = thing->z - intersect->height;
			if (P_PushDown (intersect, cpos))
			{ // Move blocked
				P_DoCrunch (intersect, cpos);
				intersect->z = oldz;
				return 2;
			}
		}
	}
	return 0;
}

//=============================================================================
//
// PIT_FloorDrop
//
//=============================================================================

void PIT_FloorDrop (AActor *thing, FChangePosition *cpos)
{
	fixed_t oldfloorz = thing->floorz;

	P_AdjustFloorCeil (thing, cpos);

	if (oldfloorz == thing->floorz) return;

	if (thing->velz == 0 &&
		(!(thing->flags & MF_NOGRAVITY) ||
		 (thing->z == oldfloorz && !(thing->flags & MF_NOLIFTDROP))))
	{
		fixed_t oldz = thing->z;

		// If float bob, always stay the same approximate distance above
		// the floor; otherwise only move things standing on the floor,
		// and only do it if the drop is slow enough.
		if (thing->flags2 & MF2_FLOATBOB)
		{
			thing->z = thing->z - oldfloorz + thing->floorz;
			P_CheckFakeFloorTriggers (thing, oldz);
		}
		else if ((thing->flags & MF_NOGRAVITY) || (thing->flags5 & MF5_MOVEWITHSECTOR) ||
			(((cpos->sector->Flags & SECF_FLOORDROP) || cpos->moveamt < 9*FRACUNIT)
			 && thing->z - thing->floorz <= cpos->moveamt))
		{
			thing->z = thing->floorz;
			P_CheckFakeFloorTriggers (thing, oldz);
		}
	}
}

//=============================================================================
//
// PIT_FloorRaise
//
//=============================================================================

void PIT_FloorRaise (AActor *thing, FChangePosition *cpos)
{
	fixed_t oldfloorz = thing->floorz;

	P_AdjustFloorCeil (thing, cpos);

	if (oldfloorz == thing->floorz) return;

	// Move things intersecting the floor up
	if (thing->z <= thing->floorz ||
		(!(thing->flags & MF_NOGRAVITY) && (thing->flags2 & MF2_FLOATBOB)))
	{
		intersectors.Clear ();
		fixed_t oldz = thing->z;
		if (!(thing->flags2 & MF2_FLOATBOB))
		{
			thing->z = thing->floorz;
		}
		else
		{
			thing->z = thing->z - oldfloorz + thing->floorz;
		}
		switch (P_PushUp (thing, cpos))
		{
		default:
			P_CheckFakeFloorTriggers (thing, oldz);
			break;
		case 1:
			P_DoCrunch (thing, cpos);
			P_CheckFakeFloorTriggers (thing, oldz);
			break;
		case 2:
			P_DoCrunch (thing, cpos);
			thing->z = oldz;
			break;
		}
	}
}

//=============================================================================
//
// PIT_CeilingLower
//
//=============================================================================

void PIT_CeilingLower (AActor *thing, FChangePosition *cpos)
{
	bool onfloor;

	onfloor = thing->z <= thing->floorz;
	P_AdjustFloorCeil (thing, cpos);

	if (thing->z + thing->height > thing->ceilingz)
	{
		intersectors.Clear ();
		fixed_t oldz = thing->z;
		if (thing->ceilingz - thing->height >= thing->floorz)
		{
			thing->z = thing->ceilingz - thing->height;
		}
		else
		{
			thing->z = thing->floorz;
		}
		switch (P_PushDown (thing, cpos))
		{
		case 2:
			// intentional fall-through
		case 1:
			if (onfloor)
				thing->z = thing->floorz;
			P_DoCrunch (thing, cpos);
			P_CheckFakeFloorTriggers (thing, oldz);
			break;
		default:
			P_CheckFakeFloorTriggers (thing, oldz);
			break;
		}
	}
}

//=============================================================================
//
// PIT_CeilingRaise
//
//=============================================================================

void PIT_CeilingRaise (AActor *thing, FChangePosition *cpos)
{
	bool isgood = P_AdjustFloorCeil (thing, cpos);

	// For DOOM compatibility, only move things that are inside the floor.
	// (or something else?) Things marked as hanging from the ceiling will
	// stay where they are.
	if (thing->z < thing->floorz &&
		thing->z + thing->height >= thing->ceilingz - cpos->moveamt &&
		!(thing->flags & MF_NOLIFTDROP))
	{
		fixed_t oldz = thing->z;
		thing->z = thing->floorz;
		if (thing->z + thing->height > thing->ceilingz)
		{
			thing->z = thing->ceilingz - thing->height;
		}
		P_CheckFakeFloorTriggers (thing, oldz);
	}
	else if ((thing->flags2 & MF2_PASSMOBJ) && !isgood && thing->z + thing->height < thing->ceilingz)
	{
		AActor *onmobj;
		if (!P_TestMobjZ (thing, true, &onmobj) && onmobj->z <= thing->z)
		{
			thing->z = MIN (thing->ceilingz - thing->height,
							onmobj->z + onmobj->height);
		}
	}
}

//=============================================================================
//
// P_ChangeSector	[RH] Was P_CheckSector in BOOM
//
// jff 3/19/98 added to just check monsters on the periphery
// of a moving sector instead of all in bounding box of the
// sector. Both more accurate and faster.
//
//=============================================================================

bool P_ChangeSector (sector_t *sector, int crunch, int amt, int floorOrCeil, bool isreset)
{
	FChangePosition cpos;
	void (*iterator)(AActor *, FChangePosition *);
	void (*iterator2)(AActor *, FChangePosition *) = NULL;
	msecnode_t *n;

	cpos.nofit = false;
	cpos.crushchange = crunch;
	cpos.moveamt = abs (amt);
	cpos.movemidtex = false;
	cpos.sector = sector;

#ifdef _3DFLOORS
	// Also process all sectors that have 3D floors transferred from the
	// changed sector.
	if(sector->e->XFloor.attached.Size())
	{
		unsigned       i;
		sector_t*      sec;


		// Use different functions for the four different types of sector movement.
		// for 3D-floors the meaning of floor and ceiling is inverted!!!
		if (floorOrCeil == 1)
		{ 
			iterator = (amt >= 0) ? PIT_FloorRaise : PIT_FloorDrop;
		}
		else
		{ 
			iterator = (amt >=0) ? PIT_CeilingRaise : PIT_CeilingLower;
		}

		for(i = 0; i < sector->e->XFloor.attached.Size(); i ++)
		{
			sec = sector->e->XFloor.attached[i];
			P_Recalculate3DFloors(sec);	// Must recalculate the 3d floor and light lists

			// no thing checks for attached sectors because of heightsec
			if (sec->heightsec==sector) continue;

			for (n=sec->touching_thinglist; n; n=n->m_snext) n->visited = false;
			do 
			{
				for (n=sec->touching_thinglist; n; n=n->m_snext)
				{
					if (!n->visited)
					{
						n->visited  = true;
						if (!(n->m_thing->flags & MF_NOBLOCKMAP) ||	//jff 4/7/98 don't do these
							(n->m_thing->flags5 & MF5_MOVEWITHSECTOR))
						{
							iterator(n->m_thing, &cpos);
						}
						break;
					}
				}
			} 
			while (n);
		}
	}
	P_Recalculate3DFloors(sector);			// Must recalculate the 3d floor and light lists
#endif


	// [RH] Use different functions for the four different types of sector
	// movement.
	switch (floorOrCeil)
	{
	case 0:
		// floor
		iterator = (amt < 0) ? PIT_FloorDrop : PIT_FloorRaise;
		break;

	case 1:
		// ceiling
		iterator = (amt < 0) ? PIT_CeilingLower : PIT_CeilingRaise;
		break;

	case 2:
		// 3dmidtex
		// This must check both floor and ceiling 
		iterator = (amt < 0) ? PIT_FloorDrop : PIT_FloorRaise;
		iterator2 = (amt < 0) ? PIT_CeilingLower : PIT_CeilingRaise;
		cpos.movemidtex = true;
		break;

	default:
		// invalid
		assert(floorOrCeil > 0 && floorOrCeil < 2);
		return false;
	}

	// killough 4/4/98: scan list front-to-back until empty or exhausted,
	// restarting from beginning after each thing is processed. Avoids
	// crashes, and is sure to examine all things in the sector, and only
	// the things which are in the sector, until a steady-state is reached.
	// Things can arbitrarily be inserted and removed and it won't mess up.
	//
	// killough 4/7/98: simplified to avoid using complicated counter

	// Mark all things invalid

	for (n = sector->touching_thinglist; n; n = n->m_snext)
		n->visited = false;

	do
	{
		for (n = sector->touching_thinglist; n; n = n->m_snext)	// go through list
		{
			if (!n->visited)								// unprocessed thing found
			{
				n->visited = true; 							// mark thing as processed
				if (!(n->m_thing->flags & MF_NOBLOCKMAP) ||	//jff 4/7/98 don't do these
					(n->m_thing->flags5 & MF5_MOVEWITHSECTOR))
				{
					iterator (n->m_thing, &cpos);		 			// process it
					if (iterator2 != NULL) iterator2 (n->m_thing, &cpos);
				}
				break;										// exit and start over
			}
		}
	} while (n);	// repeat from scratch until all things left are marked valid

	if (!cpos.nofit && !isreset /* && sector->MoreFlags & (SECF_UNDERWATERMASK)*/)
	{
		// If this is a control sector for a deep water transfer, all actors in affected
		// sectors need to have their waterlevel information updated and if applicable,
		// execute appropriate sector actions.
		// Only check if the sector move was successful.
		TArray<sector_t *> & secs = sector->e->FakeFloor.Sectors;
		for(unsigned i = 0; i < secs.Size(); i++)
		{
			sector_t * s = secs[i];

			for (n = s->touching_thinglist; n; n = n->m_snext)
				n->visited = false;

			do
			{
				for (n = s->touching_thinglist; n; n = n->m_snext)	// go through list
				{
					if (!n->visited && n->m_thing->Sector == s)		// unprocessed thing found
					{
						n->visited = true; 							// mark thing as processed

						n->m_thing->UpdateWaterLevel(n->m_thing->z, false);
						P_CheckFakeFloorTriggers(n->m_thing, n->m_thing->z - amt);
					}
				}
			} while (n);	// repeat from scratch until all things left are marked valid
		}

	}

	return cpos.nofit;
}

//=============================================================================
// phares 3/21/98
//
// Maintain a freelist of msecnode_t's to reduce memory allocs and frees.
//=============================================================================

msecnode_t *headsecnode = NULL;

//=============================================================================
//
// P_GetSecnode
//
// Retrieve a node from the freelist. The calling routine
// should make sure it sets all fields properly.
//
//=============================================================================

msecnode_t *P_GetSecnode()
{
	msecnode_t *node;

	if (headsecnode)
	{
		node = headsecnode;
		headsecnode = headsecnode->m_snext;
	}
	else
	{
		node = (msecnode_t *)M_Malloc (sizeof(*node));
	}
	return node;
}

//=============================================================================
//
// P_PutSecnode
//
// Returns a node to the freelist.
//
//=============================================================================

void P_PutSecnode (msecnode_t *node)
{
	node->m_snext = headsecnode;
	headsecnode = node;
}

//=============================================================================
// phares 3/16/98
//
// P_AddSecnode
//
// Searches the current list to see if this sector is
// already there. If not, it adds a sector node at the head of the list of
// sectors this object appears in. This is called when creating a list of
// nodes that will get linked in later. Returns a pointer to the new node.
//
//=============================================================================

msecnode_t *P_AddSecnode (sector_t *s, AActor *thing, msecnode_t *nextnode)
{
	msecnode_t *node;

	if (s == 0)
	{
		I_FatalError ("AddSecnode of 0 for %s\n", thing->_StaticType.TypeName.GetChars());
	}

	node = nextnode;
	while (node)
	{
		if (node->m_sector == s)	// Already have a node for this sector?
		{
			node->m_thing = thing;	// Yes. Setting m_thing says 'keep it'.
			return nextnode;
		}
		node = node->m_tnext;
	}

	// Couldn't find an existing node for this sector. Add one at the head
	// of the list.

	node = P_GetSecnode();

	// killough 4/4/98, 4/7/98: mark new nodes unvisited.
	node->visited = 0;

	node->m_sector = s; 			// sector
	node->m_thing  = thing; 		// mobj
	node->m_tprev  = NULL;			// prev node on Thing thread
	node->m_tnext  = nextnode;		// next node on Thing thread
	if (nextnode)
		nextnode->m_tprev = node;	// set back link on Thing

	// Add new node at head of sector thread starting at s->touching_thinglist

	node->m_sprev  = NULL;			// prev node on sector thread
	node->m_snext  = s->touching_thinglist; // next node on sector thread
	if (s->touching_thinglist)
		node->m_snext->m_sprev = node;
	s->touching_thinglist = node;
	return node;
}

//=============================================================================
//
// P_DelSecnode
//
// Deletes a sector node from the list of
// sectors this object appears in. Returns a pointer to the next node
// on the linked list, or NULL.
//
//=============================================================================

msecnode_t *P_DelSecnode (msecnode_t *node)
{
	msecnode_t* tp;  // prev node on thing thread
	msecnode_t* tn;  // next node on thing thread
	msecnode_t* sp;  // prev node on sector thread
	msecnode_t* sn;  // next node on sector thread

	if (node)
	{
		// Unlink from the Thing thread. The Thing thread begins at
		// sector_list and not from AActor->touching_sectorlist.

		tp = node->m_tprev;
		tn = node->m_tnext;
		if (tp)
			tp->m_tnext = tn;
		if (tn)
			tn->m_tprev = tp;

		// Unlink from the sector thread. This thread begins at
		// sector_t->touching_thinglist.

		sp = node->m_sprev;
		sn = node->m_snext;
		if (sp)
			sp->m_snext = sn;
		else
			node->m_sector->touching_thinglist = sn;
		if (sn)
			sn->m_sprev = sp;

		// Return this node to the freelist

		P_PutSecnode(node);
		return tn;
	}
	return NULL;
} 														// phares 3/13/98

//=============================================================================
//
// P_DelSector_List
//
// Deletes the sector_list and NULLs it.
//
//=============================================================================

void P_DelSector_List ()
{
	if (sector_list != NULL)
	{
		P_DelSeclist (sector_list);
		sector_list = NULL;
	}
}

//=============================================================================
//
// P_DelSeclist
//
// Delete an entire sector list
//
//=============================================================================

void P_DelSeclist (msecnode_t *node)
{
	while (node)
		node = P_DelSecnode (node);
}

//=============================================================================
// phares 3/14/98
//
// P_CreateSecNodeList
//
// Alters/creates the sector_list that shows what sectors the object resides in
//
//=============================================================================

void P_CreateSecNodeList (AActor *thing, fixed_t x, fixed_t y)
{
	msecnode_t *node;

	// First, clear out the existing m_thing fields. As each node is
	// added or verified as needed, m_thing will be set properly. When
	// finished, delete all nodes where m_thing is still NULL. These
	// represent the sectors the Thing has vacated.

	node = sector_list;
	while (node)
	{
		node->m_thing = NULL;
		node = node->m_tnext;
	}

	FBoundingBox box(thing->x, thing->y, thing->radius);
	FBlockLinesIterator it(box);
	line_t *ld;

	while ((ld = it.Next()))
	{
		if (box.Right()  <= ld->bbox[BOXLEFT]	 ||
			box.Left()   >= ld->bbox[BOXRIGHT]  ||
			box.Top()    <= ld->bbox[BOXBOTTOM] ||
			box.Bottom() >= ld->bbox[BOXTOP])
			continue;

		if (box.BoxOnLineSide (ld) != -1)
			continue;

		// This line crosses through the object.

		// Collect the sector(s) from the line and add to the
		// sector_list you're examining. If the Thing ends up being
		// allowed to move to this position, then the sector_list
		// will be attached to the Thing's AActor at touching_sectorlist.

		sector_list = P_AddSecnode (ld->frontsector,thing,sector_list);

		// Don't assume all lines are 2-sided, since some Things
		// like MT_TFOG are allowed regardless of whether their radius takes
		// them beyond an impassable linedef.

		// killough 3/27/98, 4/4/98:
		// Use sidedefs instead of 2s flag to determine two-sidedness.

		if (ld->backsector)
			sector_list = P_AddSecnode(ld->backsector, thing, sector_list);
	}

	// Add the sector of the (x,y) point to sector_list.

	sector_list = P_AddSecnode (thing->Sector, thing, sector_list);

	// Now delete any nodes that won't be used. These are the ones where
	// m_thing is still NULL.

	node = sector_list;
	while (node)
	{
		if (node->m_thing == NULL)
		{
			if (node == sector_list)
				sector_list = node->m_tnext;
			node = P_DelSecnode (node);
		}
		else
		{
			node = node->m_tnext;
		}
	}
}

void SpawnShootDecal (AActor *t1, const FTraceResults &trace)
{
	FDecalBase *decalbase = NULL;

	if (t1->player != NULL && t1->player->ReadyWeapon != NULL)
	{
		decalbase = t1->player->ReadyWeapon->GetDefault()->DecalGenerator;
	}
	else
	{
		decalbase = t1->DecalGenerator;
	}
	if (decalbase != NULL)
	{
		DImpactDecal::StaticCreate (decalbase->GetDecal (),
			trace.X, trace.Y, trace.Z, trace.Line->sidedef[trace.Side], trace.ffloor);
	}
}

static void SpawnDeepSplash (AActor *t1, const FTraceResults &trace, AActor *puff,
	fixed_t vx, fixed_t vy, fixed_t vz, fixed_t shootz)
{
	if (!trace.CrossedWater->heightsec) return;
	
	fixed_t num, den, hitdist;
	const secplane_t *plane = &trace.CrossedWater->heightsec->floorplane;

	den = TMulScale16 (plane->a, vx, plane->b, vy, plane->c, vz);
	if (den != 0)
	{
		num = TMulScale16 (plane->a, t1->x, plane->b, t1->y, plane->c, shootz) + plane->d;
		hitdist = FixedDiv (-num, den);

		if (hitdist >= 0 && hitdist <= trace.Distance)
		{
			fixed_t hitx = t1->x+FixedMul (vx, hitdist);
			fixed_t hity = t1->y+FixedMul (vy, hitdist);
			fixed_t hitz = shootz+FixedMul (vz, hitdist);

			P_HitWater (puff != NULL? puff:t1, P_PointInSector(hitx, hity), hitx, hity, hitz);
		}
	}
}