/*
Copyright (C) 1996-1997 Id Software, Inc.
Copyright (C) 1999,2000  contributors of the QuakeForge project
Please see the file "AUTHORS" for a list of contributors

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/
#include "quakedef.h"

static	hull_t		box_hull;
static	dclipnode_t	box_clipnodes[6];
static	mplane_t	box_planes[6];

extern	vec3_t player_mins;
extern	vec3_t player_maxs;

/*
===================
PM_InitBoxHull

Set up the planes and clipnodes so that the six floats of a bounding box
can just be stored out and get a proper hull_t structure.
===================
*/
void PM_InitBoxHull (void)
{
	int		i;
	int		side;

	box_hull.clipnodes = box_clipnodes;
	box_hull.planes = box_planes;
	box_hull.firstclipnode = 0;
	box_hull.lastclipnode = 5;

	for (i=0 ; i<6 ; i++)
	{
		box_clipnodes[i].planenum = i;
		
		side = i&1;
		
		box_clipnodes[i].children[side] = CONTENTS_EMPTY;
		if (i != 5)
			box_clipnodes[i].children[side^1] = i + 1;
		else
			box_clipnodes[i].children[side^1] = CONTENTS_SOLID;
		
		box_planes[i].type = i>>1;
		box_planes[i].normal[i>>1] = 1;
	}
	
}


/*
===================
PM_HullForBox

To keep everything totally uniform, bounding boxes are turned into small
BSP trees instead of being compared directly.
===================
*/
hull_t	*PM_HullForBox (vec3_t mins, vec3_t maxs)
{
	box_planes[0].dist = maxs[0];
	box_planes[1].dist = mins[0];
	box_planes[2].dist = maxs[1];
	box_planes[3].dist = mins[1];
	box_planes[4].dist = maxs[2];
	box_planes[5].dist = mins[2];

	return &box_hull;
}


/*
==================
PM_HullPointContents

==================
*/
int PM_HullPointContents (hull_t *hull, int num, vec3_t p)
{
	float		d;
	dclipnode_t	*node;
	mplane_t	*plane;

	while (num >= 0)
	{
		if (num < hull->firstclipnode || num > hull->lastclipnode)
			Sys_Error ("PM_HullPointContents: bad node number");
	
		node = hull->clipnodes + num;
		plane = hull->planes + node->planenum;
		
		if (plane->type < 3)
			d = p[plane->type] - plane->dist;
		else
			d = DotProduct (plane->normal, p) - plane->dist;
		if (d < 0)
			num = node->children[1];
		else
			num = node->children[0];
	}
	
	return num;
}

/*
==================
PM_PointContents

==================
*/
int PM_PointContents (vec3_t p)
{
	float		d;
	dclipnode_t	*node;
	mplane_t	*plane;
	hull_t		*hull;
	int			num;

	hull = &pmove.physents[0].model->hulls[0];

	num = hull->firstclipnode;

	while (num >= 0)
	{
		if (num < hull->firstclipnode || num > hull->lastclipnode)
			Sys_Error ("PM_HullPointContents: bad node number");
	
		node = hull->clipnodes + num;
		plane = hull->planes + node->planenum;
		
		if (plane->type < 3)
			d = p[plane->type] - plane->dist;
		else
			d = DotProduct (plane->normal, p) - plane->dist;
		if (d < 0)
			num = node->children[1];
		else
			num = node->children[0];
	}
	
	return num;
}

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

LINE TESTING IN HULLS

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

// 1/32 epsilon to keep floating point happy
#define	DIST_EPSILON	(0.03125)

/*
==================
PM_RecursiveHullCheck

==================
*/
qboolean PM_RecursiveHullCheck (hull_t *hull, int num, float p1f, float p2f, vec3_t p1, vec3_t p2, pmtrace_t *trace)
{
	dclipnode_t	*node;
	mplane_t	*plane;
	float		t1, t2;
	float		frac;
	int			i;
	vec3_t		mid;
	int			side;
	float		midf;

// check for empty
	if (num < 0)
	{
		if (num != CONTENTS_SOLID)
		{
			trace->allsolid = false;
			if (num == CONTENTS_EMPTY)
				trace->inopen = true;
			else
				trace->inwater = true;
		}
		else
			trace->startsolid = true;
		return true;		// empty
	}

	if (num < hull->firstclipnode || num > hull->lastclipnode)
		Sys_Error ("PM_RecursiveHullCheck: bad node number");

//
// find the point distances
//
	node = hull->clipnodes + num;
	plane = hull->planes + node->planenum;

	if (plane->type < 3)
	{
		t1 = p1[plane->type] - plane->dist;
		t2 = p2[plane->type] - plane->dist;
	}
	else
	{
		t1 = DotProduct (plane->normal, p1) - plane->dist;
		t2 = DotProduct (plane->normal, p2) - plane->dist;
	}
	
#if 1
	if (t1 >= 0 && t2 >= 0)
		return PM_RecursiveHullCheck (hull, node->children[0], p1f, p2f, p1, p2, trace);
	if (t1 < 0 && t2 < 0)
		return PM_RecursiveHullCheck (hull, node->children[1], p1f, p2f, p1, p2, trace);
#else
	if ( (t1 >= DIST_EPSILON && t2 >= DIST_EPSILON) || (t2 > t1 && t1 >= 0) )
		return PM_RecursiveHullCheck (hull, node->children[0], p1f, p2f, p1, p2, trace);
	if ( (t1 <= -DIST_EPSILON && t2 <= -DIST_EPSILON) || (t2 < t1 && t1 <= 0) )
		return PM_RecursiveHullCheck (hull, node->children[1], p1f, p2f, p1, p2, trace);
#endif

// put the crosspoint DIST_EPSILON pixels on the near side
	if (t1 < 0)
		frac = (t1 + DIST_EPSILON)/(t1-t2);
	else
		frac = (t1 - DIST_EPSILON)/(t1-t2);
	if (frac < 0)
		frac = 0;
	if (frac > 1)
		frac = 1;
		
	midf = p1f + (p2f - p1f)*frac;
	for (i=0 ; i<3 ; i++)
		mid[i] = p1[i] + frac*(p2[i] - p1[i]);

	side = (t1 < 0);

// move up to the node
	if (!PM_RecursiveHullCheck (hull, node->children[side], p1f, midf, p1, mid, trace) )
		return false;

//#ifdef PARANOID
//	if (PM_HullPointContents (pm_hullmodel, mid, node->children[side]) == CONTENTS_SOLID)
//	{
//		Con_Printf ("mid PointInHullSolid\n");
//		return false;
//	}
//#endif
	
	if (PM_HullPointContents (hull, node->children[side^1], mid)
	!= CONTENTS_SOLID)
// go past the node
		return PM_RecursiveHullCheck (hull, node->children[side^1], midf, p2f, mid, p2, trace);
	
	if (trace->allsolid)
		return false;		// never got out of the solid area
		
//==================
// the other side of the node is solid, this is the impact point
//==================
	if (!side)
	{
		VectorCopy (plane->normal, trace->plane.normal);
		trace->plane.dist = plane->dist;
	}
	else
	{
		VectorSubtract (vec3_origin, plane->normal, trace->plane.normal);
		trace->plane.dist = -plane->dist;
	}

	while (PM_HullPointContents (hull, hull->firstclipnode, mid)
	== CONTENTS_SOLID)
	{ // shouldn't really happen, but does occasionally
		frac -= 0.1;
		if (frac < 0)
		{
			trace->fraction = midf;
			VectorCopy (mid, trace->endpos);
			Con_DPrintf ("backup past 0\n");
			return false;
		}
		midf = p1f + (p2f - p1f)*frac;
		for (i=0 ; i<3 ; i++)
			mid[i] = p1[i] + frac*(p2[i] - p1[i]);
	}

	trace->fraction = midf;
	VectorCopy (mid, trace->endpos);

	return false;
}


/*
================
PM_TestPlayerPosition

Returns false if the given player position is not valid (in solid)
================
*/
qboolean PM_TestPlayerPosition (vec3_t pos)
{
	int			i;
	physent_t	*pe;
	vec3_t		mins, maxs, test;
	hull_t		*hull;

	for (i=0 ; i< pmove.numphysent ; i++)
	{
		pe = &pmove.physents[i];
	// get the clipping hull
		if (pe->model)
			hull = &pmove.physents[i].model->hulls[1];
		else
		{
			VectorSubtract (pe->mins, player_maxs, mins);
			VectorSubtract (pe->maxs, player_mins, maxs);
			hull = PM_HullForBox (mins, maxs);
		}

		VectorSubtract (pos, pe->origin, test);

		if (PM_HullPointContents (hull, hull->firstclipnode, test) == CONTENTS_SOLID)
			return false;
	}

	return true;
}

/*
================
PM_PlayerMove
================
*/
pmtrace_t PM_PlayerMove (vec3_t start, vec3_t end)
{
	pmtrace_t		trace, total;
	vec3_t		offset;
	vec3_t		start_l, end_l;
	hull_t		*hull;
	int			i;
	physent_t	*pe;
	vec3_t		mins, maxs;

// fill in a default trace
	memset (&total, 0, sizeof(pmtrace_t));
	total.fraction = 1;
	total.ent = -1;
	VectorCopy (end, total.endpos);

	for (i=0 ; i< pmove.numphysent ; i++)
	{
		pe = &pmove.physents[i];
	// get the clipping hull
		if (pe->model)
			hull = &pmove.physents[i].model->hulls[1];
		else
		{
			VectorSubtract (pe->mins, player_maxs, mins);
			VectorSubtract (pe->maxs, player_mins, maxs);
			hull = PM_HullForBox (mins, maxs);
		}

	// PM_HullForEntity (ent, mins, maxs, offset);
	VectorCopy (pe->origin, offset);

		VectorSubtract (start, offset, start_l);
		VectorSubtract (end, offset, end_l);

	// fill in a default trace
		memset (&trace, 0, sizeof(pmtrace_t));
		trace.fraction = 1;
		trace.allsolid = true;
//		trace.startsolid = true;
		VectorCopy (end, trace.endpos);

	// trace a line through the apropriate clipping hull
		PM_RecursiveHullCheck (hull, hull->firstclipnode, 0, 1, start_l, end_l, &trace);

		if (trace.allsolid)
			trace.startsolid = true;
		if (trace.startsolid)
			trace.fraction = 0;

	// did we clip the move?
		if (trace.fraction < total.fraction)
		{
			// fix trace up by the offset
			VectorAdd (trace.endpos, offset, trace.endpos);
			total = trace;
			total.ent = i;
		}

	}

	return total;
}