/* -------------------------------------------------------------------------------

   Copyright (C) 1999-2007 id Software, Inc. and contributors.
   For a list of contributors, see the accompanying CONTRIBUTORS file.

   This file is part of GtkRadiant.

   GtkRadiant 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.

   GtkRadiant 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 GtkRadiant; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

   ----------------------------------------------------------------------------------

   This code has been altered significantly from its original form, to support
   several games based on the Quake III Arena engine, in the form of "Q3Map2."

   ------------------------------------------------------------------------------- */



/* marker */
#define VISFLOW_C



/* dependencies */
#include "vmap.h"




/*

   each portal will have a list of all possible to see from first portal

   if (!thread->portalmightsee[portalnum])

   portal mightsee

   for p2 = all other portals in leaf
    get sperating planes
    for all portals that might be seen by p2
        mark as unseen if not present in seperating plane
    flood fill a new mightsee
    save as passagemightsee


   void CalcMightSee (leaf_t *leaf,
 */

int CountBits( byte *bits, int numbits ){
	int i;
	int c;

	c = 0;
	for ( i = 0 ; i < numbits ; i++ )
		if ( bits[i >> 3] & ( 1 << ( i & 7 ) ) ) {
			c++;
		}

	return c;
}

int c_fullskip;

int c_chop, c_nochop;

int active;

void CheckStack( leaf_t *leaf, threaddata_t *thread ){
	pstack_t    *p, *p2;

	for ( p = thread->pstack_head.next ; p ; p = p->next )
	{
//		Sys_Printf ("=");
		if ( p->leaf == leaf ) {
			Error( "CheckStack: leaf recursion" );
		}
		for ( p2 = thread->pstack_head.next ; p2 != p ; p2 = p2->next )
			if ( p2->leaf == p->leaf ) {
				Error( "CheckStack: late leaf recursion" );
			}
	}
//	Sys_Printf ("\n");
}


fixedWinding_t *AllocStackWinding( pstack_t *stack ){
	int i;

	for ( i = 0 ; i < 3 ; i++ )
	{
		if ( stack->freewindings[i] ) {
			stack->freewindings[i] = 0;
			return &stack->windings[i];
		}
	}

	Error( "AllocStackWinding: failed" );

	return NULL;
}

void FreeStackWinding( fixedWinding_t *w, pstack_t *stack ){
	int i;

	i = w - stack->windings;

	if ( i < 0 || i > 2 ) {
		return;     // not from local

	}
	if ( stack->freewindings[i] ) {
		Error( "FreeStackWinding: allready free" );
	}
	stack->freewindings[i] = 1;
}

/*
   ==============
   VisChopWinding

   ==============
 */
fixedWinding_t  *VisChopWinding( fixedWinding_t *in, pstack_t *stack, visPlane_t *split ){
	vec_t dists[128];
	int sides[128];
	int counts[3];
	vec_t dot;
	int i, j;
	vec_t   *p1, *p2;
	vec3_t mid;
	fixedWinding_t  *neww;

	counts[0] = counts[1] = counts[2] = 0;

	// determine sides for each point
	for ( i = 0 ; i < in->numpoints ; i++ )
	{
		dot = DotProduct( in->points[i], split->normal );
		dot -= split->dist;
		dists[i] = dot;
		if ( dot > ON_EPSILON ) {
			sides[i] = SIDE_FRONT;
		}
		else if ( dot < -ON_EPSILON ) {
			sides[i] = SIDE_BACK;
		}
		else
		{
			sides[i] = SIDE_ON;
		}
		counts[sides[i]]++;
	}

	if ( !counts[1] ) {
		return in;      // completely on front side

	}
	if ( !counts[0] ) {
		FreeStackWinding( in, stack );
		return NULL;
	}

	sides[i] = sides[0];
	dists[i] = dists[0];

	neww = AllocStackWinding( stack );

	neww->numpoints = 0;

	for ( i = 0 ; i < in->numpoints ; i++ )
	{
		p1 = in->points[i];

		if ( neww->numpoints == MAX_POINTS_ON_FIXED_WINDING ) {
			FreeStackWinding( neww, stack );
			return in;      // can't chop -- fall back to original
		}

		if ( sides[i] == SIDE_ON ) {
			VectorCopy( p1, neww->points[neww->numpoints] );
			neww->numpoints++;
			continue;
		}

		if ( sides[i] == SIDE_FRONT ) {
			VectorCopy( p1, neww->points[neww->numpoints] );
			neww->numpoints++;
		}

		if ( sides[i + 1] == SIDE_ON || sides[i + 1] == sides[i] ) {
			continue;
		}

		if ( neww->numpoints == MAX_POINTS_ON_FIXED_WINDING ) {
			FreeStackWinding( neww, stack );
			return in;      // can't chop -- fall back to original
		}

		// generate a split point
		p2 = in->points[( i + 1 ) % in->numpoints];

		dot = dists[i] / ( dists[i] - dists[i + 1] );
		for ( j = 0 ; j < 3 ; j++ )
		{   // avoid round off error when possible
			if ( split->normal[j] == 1 ) {
				mid[j] = split->dist;
			}
			else if ( split->normal[j] == -1 ) {
				mid[j] = -split->dist;
			}
			else{
				mid[j] = p1[j] + dot * ( p2[j] - p1[j] );
			}
		}

		VectorCopy( mid, neww->points[neww->numpoints] );
		neww->numpoints++;
	}

	// free the original winding
	FreeStackWinding( in, stack );

	return neww;
}

/*
   ==============
   ClipToSeperators

   Source, pass, and target are an ordering of portals.

   Generates seperating planes canidates by taking two points from source and one
   point from pass, and clips target by them.

   If target is totally clipped away, that portal can not be seen through.

   Normal clip keeps target on the same side as pass, which is correct if the
   order goes source, pass, target.  If the order goes pass, source, target then
   flipclip should be set.
   ==============
 */
fixedWinding_t  *ClipToSeperators( fixedWinding_t *source, fixedWinding_t *pass, fixedWinding_t *target, qboolean flipclip, pstack_t *stack ){
	int i, j, k, l;
	visPlane_t plane;
	vec3_t v1, v2;
	float d;
	vec_t length;
	int counts[3];
	qboolean fliptest;

	// check all combinations
	for ( i = 0 ; i < source->numpoints ; i++ )
	{
		l = ( i + 1 ) % source->numpoints;
		VectorSubtract( source->points[l], source->points[i], v1 );

		// find a vertex of pass that makes a plane that puts all of the
		// vertexes of pass on the front side and all of the vertexes of
		// source on the back side
		for ( j = 0 ; j < pass->numpoints ; j++ )
		{
			VectorSubtract( pass->points[j], source->points[i], v2 );

			plane.normal[0] = v1[1] * v2[2] - v1[2] * v2[1];
			plane.normal[1] = v1[2] * v2[0] - v1[0] * v2[2];
			plane.normal[2] = v1[0] * v2[1] - v1[1] * v2[0];

			// if points don't make a valid plane, skip it

			length = plane.normal[0] * plane.normal[0]
					 + plane.normal[1] * plane.normal[1]
					 + plane.normal[2] * plane.normal[2];

			if ( length < ON_EPSILON ) {
				continue;
			}

			length = 1 / sqrt( length );

			plane.normal[0] *= length;
			plane.normal[1] *= length;
			plane.normal[2] *= length;

			plane.dist = DotProduct( pass->points[j], plane.normal );

			//
			// find out which side of the generated seperating plane has the
			// source portal
			//
#if 1
			fliptest = qfalse;
			for ( k = 0 ; k < source->numpoints ; k++ )
			{
				if ( k == i || k == l ) {
					continue;
				}
				d = DotProduct( source->points[k], plane.normal ) - plane.dist;
				if ( d < -ON_EPSILON ) { // source is on the negative side, so we want all
					                    // pass and target on the positive side
					fliptest = qfalse;
					break;
				}
				else if ( d > ON_EPSILON ) { // source is on the positive side, so we want all
					                        // pass and target on the negative side
					fliptest = qtrue;
					break;
				}
			}
			if ( k == source->numpoints ) {
				continue;       // planar with source portal
			}
#else
			fliptest = flipclip;
#endif
			//
			// flip the normal if the source portal is backwards
			//
			if ( fliptest ) {
				VectorSubtract( vec3_origin, plane.normal, plane.normal );
				plane.dist = -plane.dist;
			}
#if 1
			//
			// if all of the pass portal points are now on the positive side,
			// this is the seperating plane
			//
			counts[0] = counts[1] = counts[2] = 0;
			for ( k = 0 ; k < pass->numpoints ; k++ )
			{
				if ( k == j ) {
					continue;
				}
				d = DotProduct( pass->points[k], plane.normal ) - plane.dist;
				if ( d < -ON_EPSILON ) {
					break;
				}
				else if ( d > ON_EPSILON ) {
					counts[0]++;
				}
				else{
					counts[2]++;
				}
			}
			if ( k != pass->numpoints ) {
				continue;   // points on negative side, not a seperating plane

			}
			if ( !counts[0] ) {
				continue;   // planar with seperating plane
			}
#else
			k = ( j + 1 ) % pass->numpoints;
			d = DotProduct( pass->points[k], plane.normal ) - plane.dist;
			if ( d < -ON_EPSILON ) {
				continue;
			}
			k = ( j + pass->numpoints - 1 ) % pass->numpoints;
			d = DotProduct( pass->points[k], plane.normal ) - plane.dist;
			if ( d < -ON_EPSILON ) {
				continue;
			}
#endif
			//
			// flip the normal if we want the back side
			//
			if ( flipclip ) {
				VectorSubtract( vec3_origin, plane.normal, plane.normal );
				plane.dist = -plane.dist;
			}

#ifdef SEPERATORCACHE
			stack->seperators[flipclip][stack->numseperators[flipclip]] = plane;
			if ( ++stack->numseperators[flipclip] >= MAX_SEPERATORS ) {
				Error( "MAX_SEPERATORS" );
			}
#endif
			//MrE: fast check first
			d = DotProduct( stack->portal->origin, plane.normal ) - plane.dist;
			//if completely at the back of the seperator plane
			if ( d < -stack->portal->radius ) {
				return NULL;
			}
			//if completely on the front of the seperator plane
			if ( d > stack->portal->radius ) {
				break;
			}

			//
			// clip target by the seperating plane
			//
			target = VisChopWinding( target, stack, &plane );
			if ( !target ) {
				return NULL;        // target is not visible

			}
			break;      // optimization by Antony Suter
		}
	}

	return target;
}

/*
   ==================
   RecursiveLeafFlow

   Flood fill through the leafs
   If src_portal is NULL, this is the originating leaf
   ==================
 */
void RecursiveLeafFlow( int leafnum, threaddata_t *thread, pstack_t *prevstack ){
	pstack_t stack;
	vportal_t   *p;
	visPlane_t backplane;
	leaf_t      *leaf;
	int i, j, n;
	long        *test, *might, *prevmight, *vis, more;
	int pnum;

	thread->c_chains++;

	leaf = &leafs[leafnum];
//	CheckStack (leaf, thread);

	prevstack->next = &stack;

	stack.next = NULL;
	stack.leaf = leaf;
	stack.portal = NULL;
	stack.depth = prevstack->depth + 1;

#ifdef SEPERATORCACHE
	stack.numseperators[0] = 0;
	stack.numseperators[1] = 0;
#endif

	might = (long *)stack.mightsee;
	vis = (long *)thread->base->portalvis;

	// check all portals for flowing into other leafs
	for ( i = 0; i < leaf->numportals; i++ )
	{
		p = leaf->portals[i];
		if ( p->removed ) {
			continue;
		}
		pnum = p - portals;

		/* MrE: portal trace debug code
		   {
		    int portaltrace[] = {13, 16, 17, 37};
		    pstack_t *s;

		    s = &thread->pstack_head;
		    for (j = 0; s->next && j < sizeof(portaltrace)/sizeof(int) - 1; j++, s = s->next)
		    {
		        if (s->portal->num != portaltrace[j])
		            break;
		    }
		    if (j >= sizeof(portaltrace)/sizeof(int) - 1)
		    {
		        if (p->num == portaltrace[j])
		            n = 0; //traced through all the portals
		    }
		   }
		 */

		if ( !( prevstack->mightsee[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) ) {
			continue;   // can't possibly see it
		}

		// if the portal can't see anything we haven't allready seen, skip it
		if ( p->status == stat_done ) {
			test = (long *)p->portalvis;
		}
		else
		{
			test = (long *)p->portalflood;
		}

		more = 0;
		prevmight = (long *)prevstack->mightsee;
		for ( j = 0 ; j < portallongs ; j++ )
		{
			might[j] = prevmight[j] & test[j];
			more |= ( might[j] & ~vis[j] );
		}

		if ( !more &&
			 ( thread->base->portalvis[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) ) { // can't see anything new
			continue;
		}

		// get plane of portal, point normal into the neighbor leaf
		stack.portalplane = p->plane;
		VectorSubtract( vec3_origin, p->plane.normal, backplane.normal );
		backplane.dist = -p->plane.dist;

//		c_portalcheck++;

		stack.portal = p;
		stack.next = NULL;
		stack.freewindings[0] = 1;
		stack.freewindings[1] = 1;
		stack.freewindings[2] = 1;

#if 1
		{
			float d;

			d = DotProduct( p->origin, thread->pstack_head.portalplane.normal );
			d -= thread->pstack_head.portalplane.dist;
			if ( d < -p->radius ) {
				continue;
			}
			else if ( d > p->radius ) {
				stack.pass = p->winding;
			}
			else
			{
				stack.pass = VisChopWinding( p->winding, &stack, &thread->pstack_head.portalplane );
				if ( !stack.pass ) {
					continue;
				}
			}
		}
#else
		stack.pass = VisChopWinding( p->winding, &stack, &thread->pstack_head.portalplane );
		if ( !stack.pass ) {
			continue;
		}
#endif


#if 1
		{
			float d;

			d = DotProduct( thread->base->origin, p->plane.normal );
			d -= p->plane.dist;
			//MrE: vis-bug fix
			//if (d > p->radius)
			if ( d > thread->base->radius ) {
				continue;
			}
			//MrE: vis-bug fix
			//if (d < -p->radius)
			else if ( d < -thread->base->radius ) {
				stack.source = prevstack->source;
			}
			else
			{
				stack.source = VisChopWinding( prevstack->source, &stack, &backplane );
				//FIXME: shouldn't we create a new source origin and radius for fast checks?
				if ( !stack.source ) {
					continue;
				}
			}
		}
#else
		stack.source = VisChopWinding( prevstack->source, &stack, &backplane );
		if ( !stack.source ) {
			continue;
		}
#endif

		if ( !prevstack->pass ) { // the second leaf can only be blocked if coplanar

			// mark the portal as visible
			thread->base->portalvis[pnum >> 3] |= ( 1 << ( pnum & 7 ) );

			RecursiveLeafFlow( p->leaf, thread, &stack );
			continue;
		}

#ifdef SEPERATORCACHE
		if ( stack.numseperators[0] ) {
			for ( n = 0; n < stack.numseperators[0]; n++ )
			{
				stack.pass = VisChopWinding( stack.pass, &stack, &stack.seperators[0][n] );
				if ( !stack.pass ) {
					break;      // target is not visible
				}
			}
			if ( n < stack.numseperators[0] ) {
				continue;
			}
		}
		else
		{
			stack.pass = ClipToSeperators( prevstack->source, prevstack->pass, stack.pass, qfalse, &stack );
		}
#else
		stack.pass = ClipToSeperators( stack.source, prevstack->pass, stack.pass, qfalse, &stack );
#endif
		if ( !stack.pass ) {
			continue;
		}

#ifdef SEPERATORCACHE
		if ( stack.numseperators[1] ) {
			for ( n = 0; n < stack.numseperators[1]; n++ )
			{
				stack.pass = VisChopWinding( stack.pass, &stack, &stack.seperators[1][n] );
				if ( !stack.pass ) {
					break;      // target is not visible
				}
			}
		}
		else
		{
			stack.pass = ClipToSeperators( prevstack->pass, prevstack->source, stack.pass, qtrue, &stack );
		}
#else
		stack.pass = ClipToSeperators( prevstack->pass, stack.source, stack.pass, qtrue, &stack );
#endif
		if ( !stack.pass ) {
			continue;
		}

		// mark the portal as visible
		thread->base->portalvis[pnum >> 3] |= ( 1 << ( pnum & 7 ) );

		// flow through it for real
		RecursiveLeafFlow( p->leaf, thread, &stack );
		//
		stack.next = NULL;
	}
}

/*
   ===============
   PortalFlow

   generates the portalvis bit vector
   ===============
 */
void PortalFlow( int portalnum ){
	threaddata_t data;
	int i;
	vportal_t       *p;
	int c_might, c_can;

#ifdef MREDEBUG
	Sys_Printf( "\r%6d", portalnum );
#endif

	p = sorted_portals[portalnum];

	if ( p->removed ) {
		p->status = stat_done;
		return;
	}

	p->status = stat_working;

	c_might = CountBits( p->portalflood, numportals * 2 );

	memset( &data, 0, sizeof( data ) );
	data.base = p;

	data.pstack_head.portal = p;
	data.pstack_head.source = p->winding;
	data.pstack_head.portalplane = p->plane;
	data.pstack_head.depth = 0;
	for ( i = 0 ; i < portallongs ; i++ )
		( (long *)data.pstack_head.mightsee )[i] = ( (long *)p->portalflood )[i];

	RecursiveLeafFlow( p->leaf, &data, &data.pstack_head );

	p->status = stat_done;

	c_can = CountBits( p->portalvis, numportals * 2 );

	Sys_FPrintf( SYS_VRB,"portal:%4i  mightsee:%4i  cansee:%4i (%i chains)\n",
				 (int)( p - portals ), c_might, c_can, data.c_chains );
}

/*
   ==================
   RecursivePassageFlow
   ==================
 */
void RecursivePassageFlow( vportal_t *portal, threaddata_t *thread, pstack_t *prevstack ){
	pstack_t stack;
	vportal_t   *p;
	leaf_t      *leaf;
	passage_t   *passage, *nextpassage;
	int i, j;
	long        *might, *vis, *prevmight, *cansee, *portalvis, more;
	int pnum;

	leaf = &leafs[portal->leaf];

	prevstack->next = &stack;

	stack.next = NULL;
	stack.depth = prevstack->depth + 1;

	vis = (long *)thread->base->portalvis;

	passage = portal->passages;
	nextpassage = passage;
	// check all portals for flowing into other leafs
	for ( i = 0; i < leaf->numportals; i++, passage = nextpassage )
	{
		p = leaf->portals[i];
		if ( p->removed ) {
			continue;
		}
		nextpassage = passage->next;
		pnum = p - portals;

		if ( !( prevstack->mightsee[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) ) {
			continue;   // can't possibly see it
		}

		// mark the portal as visible
		thread->base->portalvis[pnum >> 3] |= ( 1 << ( pnum & 7 ) );

		prevmight = (long *)prevstack->mightsee;
		cansee = (long *)passage->cansee;
		might = (long *)stack.mightsee;
		memcpy( might, prevmight, portalbytes );
		if ( p->status == stat_done ) {
			portalvis = (long *) p->portalvis;
		}
		else{
			portalvis = (long *) p->portalflood;
		}
		more = 0;
		for ( j = 0; j < portallongs; j++ )
		{
			if ( *might ) {
				*might &= *cansee++ & *portalvis++;
				more |= ( *might & ~vis[j] );
			}
			else
			{
				cansee++;
				portalvis++;
			}
			might++;
		}

		if ( !more ) {
			// can't see anything new
			continue;
		}

		// flow through it for real
		RecursivePassageFlow( p, thread, &stack );

		stack.next = NULL;
	}
}

/*
   ===============
   PassageFlow
   ===============
 */
void PassageFlow( int portalnum ){
	threaddata_t data;
	int i;
	vportal_t       *p;
//	int				c_might, c_can;

#ifdef MREDEBUG
	Sys_Printf( "\r%6d", portalnum );
#endif

	p = sorted_portals[portalnum];

	if ( p->removed ) {
		p->status = stat_done;
		return;
	}

	p->status = stat_working;

//	c_might = CountBits (p->portalflood, numportals*2);

	memset( &data, 0, sizeof( data ) );
	data.base = p;

	data.pstack_head.portal = p;
	data.pstack_head.source = p->winding;
	data.pstack_head.portalplane = p->plane;
	data.pstack_head.depth = 0;
	for ( i = 0 ; i < portallongs ; i++ )
		( (long *)data.pstack_head.mightsee )[i] = ( (long *)p->portalflood )[i];

	RecursivePassageFlow( p, &data, &data.pstack_head );

	p->status = stat_done;

	/*
	   c_can = CountBits (p->portalvis, numportals*2);

	   Sys_FPrintf (SYS_VRB,"portal:%4i  mightsee:%4i  cansee:%4i (%i chains)\n",
	    (int)(p - portals),	c_might, c_can, data.c_chains);
	 */
}

/*
   ==================
   RecursivePassagePortalFlow
   ==================
 */
void RecursivePassagePortalFlow( vportal_t *portal, threaddata_t *thread, pstack_t *prevstack ){
	pstack_t stack;
	vportal_t   *p;
	leaf_t      *leaf;
	visPlane_t backplane;
	passage_t   *passage, *nextpassage;
	int i, j, n;
	long        *might, *vis, *prevmight, *cansee, *portalvis, more;
	int pnum;

//	thread->c_chains++;

	leaf = &leafs[portal->leaf];
//	CheckStack (leaf, thread);

	prevstack->next = &stack;

	stack.next = NULL;
	stack.leaf = leaf;
	stack.portal = NULL;
	stack.depth = prevstack->depth + 1;

#ifdef SEPERATORCACHE
	stack.numseperators[0] = 0;
	stack.numseperators[1] = 0;
#endif

	vis = (long *)thread->base->portalvis;

	passage = portal->passages;
	nextpassage = passage;
	// check all portals for flowing into other leafs
	for ( i = 0; i < leaf->numportals; i++, passage = nextpassage )
	{
		p = leaf->portals[i];
		if ( p->removed ) {
			continue;
		}
		nextpassage = passage->next;
		pnum = p - portals;

		if ( !( prevstack->mightsee[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) ) {
			continue;   // can't possibly see it

		}
		prevmight = (long *)prevstack->mightsee;
		cansee = (long *)passage->cansee;
		might = (long *)stack.mightsee;
		memcpy( might, prevmight, portalbytes );
		if ( p->status == stat_done ) {
			portalvis = (long *) p->portalvis;
		}
		else{
			portalvis = (long *) p->portalflood;
		}
		more = 0;
		for ( j = 0; j < portallongs; j++ )
		{
			if ( *might ) {
				*might &= *cansee++ & *portalvis++;
				more |= ( *might & ~vis[j] );
			}
			else
			{
				cansee++;
				portalvis++;
			}
			might++;
		}

		if ( !more && ( thread->base->portalvis[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) ) { // can't see anything new
			continue;
		}

		// get plane of portal, point normal into the neighbor leaf
		stack.portalplane = p->plane;
		VectorSubtract( vec3_origin, p->plane.normal, backplane.normal );
		backplane.dist = -p->plane.dist;

//		c_portalcheck++;

		stack.portal = p;
		stack.next = NULL;
		stack.freewindings[0] = 1;
		stack.freewindings[1] = 1;
		stack.freewindings[2] = 1;

#if 1
		{
			float d;

			d = DotProduct( p->origin, thread->pstack_head.portalplane.normal );
			d -= thread->pstack_head.portalplane.dist;
			if ( d < -p->radius ) {
				continue;
			}
			else if ( d > p->radius ) {
				stack.pass = p->winding;
			}
			else
			{
				stack.pass = VisChopWinding( p->winding, &stack, &thread->pstack_head.portalplane );
				if ( !stack.pass ) {
					continue;
				}
			}
		}
#else
		stack.pass = VisChopWinding( p->winding, &stack, &thread->pstack_head.portalplane );
		if ( !stack.pass ) {
			continue;
		}
#endif


#if 1
		{
			float d;

			d = DotProduct( thread->base->origin, p->plane.normal );
			d -= p->plane.dist;
			//MrE: vis-bug fix
			//if (d > p->radius)
			if ( d > thread->base->radius ) {
				continue;
			}
			//MrE: vis-bug fix
			//if (d < -p->radius)
			else if ( d < -thread->base->radius ) {
				stack.source = prevstack->source;
			}
			else
			{
				stack.source = VisChopWinding( prevstack->source, &stack, &backplane );
				//FIXME: shouldn't we create a new source origin and radius for fast checks?
				if ( !stack.source ) {
					continue;
				}
			}
		}
#else
		stack.source = VisChopWinding( prevstack->source, &stack, &backplane );
		if ( !stack.source ) {
			continue;
		}
#endif

		if ( !prevstack->pass ) { // the second leaf can only be blocked if coplanar

			// mark the portal as visible
			thread->base->portalvis[pnum >> 3] |= ( 1 << ( pnum & 7 ) );

			RecursivePassagePortalFlow( p, thread, &stack );
			continue;
		}

#ifdef SEPERATORCACHE
		if ( stack.numseperators[0] ) {
			for ( n = 0; n < stack.numseperators[0]; n++ )
			{
				stack.pass = VisChopWinding( stack.pass, &stack, &stack.seperators[0][n] );
				if ( !stack.pass ) {
					break;      // target is not visible
				}
			}
			if ( n < stack.numseperators[0] ) {
				continue;
			}
		}
		else
		{
			stack.pass = ClipToSeperators( prevstack->source, prevstack->pass, stack.pass, qfalse, &stack );
		}
#else
		stack.pass = ClipToSeperators( stack.source, prevstack->pass, stack.pass, qfalse, &stack );
#endif
		if ( !stack.pass ) {
			continue;
		}

#ifdef SEPERATORCACHE
		if ( stack.numseperators[1] ) {
			for ( n = 0; n < stack.numseperators[1]; n++ )
			{
				stack.pass = VisChopWinding( stack.pass, &stack, &stack.seperators[1][n] );
				if ( !stack.pass ) {
					break;      // target is not visible
				}
			}
		}
		else
		{
			stack.pass = ClipToSeperators( prevstack->pass, prevstack->source, stack.pass, qtrue, &stack );
		}
#else
		stack.pass = ClipToSeperators( prevstack->pass, stack.source, stack.pass, qtrue, &stack );
#endif
		if ( !stack.pass ) {
			continue;
		}

		// mark the portal as visible
		thread->base->portalvis[pnum >> 3] |= ( 1 << ( pnum & 7 ) );

		// flow through it for real
		RecursivePassagePortalFlow( p, thread, &stack );
		//
		stack.next = NULL;
	}
}

/*
   ===============
   PassagePortalFlow
   ===============
 */
void PassagePortalFlow( int portalnum ){
	threaddata_t data;
	int i;
	vportal_t       *p;
//	int				c_might, c_can;

#ifdef MREDEBUG
	Sys_Printf( "\r%6d", portalnum );
#endif

	p = sorted_portals[portalnum];

	if ( p->removed ) {
		p->status = stat_done;
		return;
	}

	p->status = stat_working;

//	c_might = CountBits (p->portalflood, numportals*2);

	memset( &data, 0, sizeof( data ) );
	data.base = p;

	data.pstack_head.portal = p;
	data.pstack_head.source = p->winding;
	data.pstack_head.portalplane = p->plane;
	data.pstack_head.depth = 0;
	for ( i = 0 ; i < portallongs ; i++ )
		( (long *)data.pstack_head.mightsee )[i] = ( (long *)p->portalflood )[i];

	RecursivePassagePortalFlow( p, &data, &data.pstack_head );

	p->status = stat_done;

	/*
	   c_can = CountBits (p->portalvis, numportals*2);

	   Sys_FPrintf (SYS_VRB,"portal:%4i  mightsee:%4i  cansee:%4i (%i chains)\n",
	    (int)(p - portals),	c_might, c_can, data.c_chains);
	 */
}

fixedWinding_t *PassageChopWinding( fixedWinding_t *in, fixedWinding_t *out, visPlane_t *split ){
	vec_t dists[128];
	int sides[128];
	int counts[3];
	vec_t dot;
	int i, j;
	vec_t   *p1, *p2;
	vec3_t mid;
	fixedWinding_t  *neww;

	counts[0] = counts[1] = counts[2] = 0;

	// determine sides for each point
	for ( i = 0 ; i < in->numpoints ; i++ )
	{
		dot = DotProduct( in->points[i], split->normal );
		dot -= split->dist;
		dists[i] = dot;
		if ( dot > ON_EPSILON ) {
			sides[i] = SIDE_FRONT;
		}
		else if ( dot < -ON_EPSILON ) {
			sides[i] = SIDE_BACK;
		}
		else
		{
			sides[i] = SIDE_ON;
		}
		counts[sides[i]]++;
	}

	if ( !counts[1] ) {
		return in;      // completely on front side

	}
	if ( !counts[0] ) {
		return NULL;
	}

	sides[i] = sides[0];
	dists[i] = dists[0];

	neww = out;

	neww->numpoints = 0;

	for ( i = 0 ; i < in->numpoints ; i++ )
	{
		p1 = in->points[i];

		if ( neww->numpoints == MAX_POINTS_ON_FIXED_WINDING ) {
			return in;      // can't chop -- fall back to original
		}

		if ( sides[i] == SIDE_ON ) {
			VectorCopy( p1, neww->points[neww->numpoints] );
			neww->numpoints++;
			continue;
		}

		if ( sides[i] == SIDE_FRONT ) {
			VectorCopy( p1, neww->points[neww->numpoints] );
			neww->numpoints++;
		}

		if ( sides[i + 1] == SIDE_ON || sides[i + 1] == sides[i] ) {
			continue;
		}

		if ( neww->numpoints == MAX_POINTS_ON_FIXED_WINDING ) {
			return in;      // can't chop -- fall back to original
		}

		// generate a split point
		p2 = in->points[( i + 1 ) % in->numpoints];

		dot = dists[i] / ( dists[i] - dists[i + 1] );
		for ( j = 0 ; j < 3 ; j++ )
		{   // avoid round off error when possible
			if ( split->normal[j] == 1 ) {
				mid[j] = split->dist;
			}
			else if ( split->normal[j] == -1 ) {
				mid[j] = -split->dist;
			}
			else{
				mid[j] = p1[j] + dot * ( p2[j] - p1[j] );
			}
		}

		VectorCopy( mid, neww->points[neww->numpoints] );
		neww->numpoints++;
	}

	return neww;
}

/*
   ===============
   AddSeperators
   ===============
 */
int AddSeperators( fixedWinding_t *source, fixedWinding_t *pass, qboolean flipclip, visPlane_t *seperators, int maxseperators ){
	int i, j, k, l;
	visPlane_t plane;
	vec3_t v1, v2;
	float d;
	vec_t length;
	int counts[3], numseperators;
	qboolean fliptest;

	numseperators = 0;
	// check all combinations
	for ( i = 0 ; i < source->numpoints ; i++ )
	{
		l = ( i + 1 ) % source->numpoints;
		VectorSubtract( source->points[l], source->points[i], v1 );

		// find a vertex of pass that makes a plane that puts all of the
		// vertexes of pass on the front side and all of the vertexes of
		// source on the back side
		for ( j = 0 ; j < pass->numpoints ; j++ )
		{
			VectorSubtract( pass->points[j], source->points[i], v2 );

			plane.normal[0] = v1[1] * v2[2] - v1[2] * v2[1];
			plane.normal[1] = v1[2] * v2[0] - v1[0] * v2[2];
			plane.normal[2] = v1[0] * v2[1] - v1[1] * v2[0];

			// if points don't make a valid plane, skip it

			length = plane.normal[0] * plane.normal[0]
					 + plane.normal[1] * plane.normal[1]
					 + plane.normal[2] * plane.normal[2];

			if ( length < ON_EPSILON ) {
				continue;
			}

			length = 1 / sqrt( length );

			plane.normal[0] *= length;
			plane.normal[1] *= length;
			plane.normal[2] *= length;

			plane.dist = DotProduct( pass->points[j], plane.normal );

			//
			// find out which side of the generated seperating plane has the
			// source portal
			//
#if 1
			fliptest = qfalse;
			for ( k = 0 ; k < source->numpoints ; k++ )
			{
				if ( k == i || k == l ) {
					continue;
				}
				d = DotProduct( source->points[k], plane.normal ) - plane.dist;
				if ( d < -ON_EPSILON ) { // source is on the negative side, so we want all
					                    // pass and target on the positive side
					fliptest = qfalse;
					break;
				}
				else if ( d > ON_EPSILON ) { // source is on the positive side, so we want all
					                        // pass and target on the negative side
					fliptest = qtrue;
					break;
				}
			}
			if ( k == source->numpoints ) {
				continue;       // planar with source portal
			}
#else
			fliptest = flipclip;
#endif
			//
			// flip the normal if the source portal is backwards
			//
			if ( fliptest ) {
				VectorSubtract( vec3_origin, plane.normal, plane.normal );
				plane.dist = -plane.dist;
			}
#if 1
			//
			// if all of the pass portal points are now on the positive side,
			// this is the seperating plane
			//
			counts[0] = counts[1] = counts[2] = 0;
			for ( k = 0 ; k < pass->numpoints ; k++ )
			{
				if ( k == j ) {
					continue;
				}
				d = DotProduct( pass->points[k], plane.normal ) - plane.dist;
				if ( d < -ON_EPSILON ) {
					break;
				}
				else if ( d > ON_EPSILON ) {
					counts[0]++;
				}
				else{
					counts[2]++;
				}
			}
			if ( k != pass->numpoints ) {
				continue;   // points on negative side, not a seperating plane

			}
			if ( !counts[0] ) {
				continue;   // planar with seperating plane
			}
#else
			k = ( j + 1 ) % pass->numpoints;
			d = DotProduct( pass->points[k], plane.normal ) - plane.dist;
			if ( d < -ON_EPSILON ) {
				continue;
			}
			k = ( j + pass->numpoints - 1 ) % pass->numpoints;
			d = DotProduct( pass->points[k], plane.normal ) - plane.dist;
			if ( d < -ON_EPSILON ) {
				continue;
			}
#endif
			//
			// flip the normal if we want the back side
			//
			if ( flipclip ) {
				VectorSubtract( vec3_origin, plane.normal, plane.normal );
				plane.dist = -plane.dist;
			}

			if ( numseperators >= maxseperators ) {
				Error( "max seperators" );
			}
			seperators[numseperators] = plane;
			numseperators++;
			break;
		}
	}
	return numseperators;
}

/*
   ===============
   CreatePassages

   MrE: create passages from one portal to all the portals in the leaf the portal leads to
     every passage has a cansee bit string with all the portals that can be
     seen through the passage
   ===============
 */
void CreatePassages( int portalnum ){
	int i, j, k, n, numseperators, numsee;
	float d;
	vportal_t       *portal, *p, *target;
	leaf_t          *leaf;
	passage_t       *passage, *lastpassage;
	visPlane_t seperators[MAX_SEPERATORS * 2];
	fixedWinding_t  *w;
	fixedWinding_t in, out, *res;


#ifdef MREDEBUG
	Sys_Printf( "\r%6d", portalnum );
#endif

	portal = sorted_portals[portalnum];

	if ( portal->removed ) {
		portal->status = stat_done;
		return;
	}

	lastpassage = NULL;
	leaf = &leafs[portal->leaf];
	for ( i = 0; i < leaf->numportals; i++ )
	{
		target = leaf->portals[i];
		if ( target->removed ) {
			continue;
		}

		passage = (passage_t *) safe_malloc( sizeof( passage_t ) + portalbytes );
		memset( passage, 0, sizeof( passage_t ) + portalbytes );
		numseperators = AddSeperators( portal->winding, target->winding, qfalse, seperators, MAX_SEPERATORS * 2 );
		numseperators += AddSeperators( target->winding, portal->winding, qtrue, &seperators[numseperators], MAX_SEPERATORS * 2 - numseperators );

		passage->next = NULL;
		if ( lastpassage ) {
			lastpassage->next = passage;
		}
		else{
			portal->passages = passage;
		}
		lastpassage = passage;

		numsee = 0;
		//create the passage->cansee
		for ( j = 0; j < numportals * 2; j++ )
		{
			p = &portals[j];
			if ( p->removed ) {
				continue;
			}
			if ( !( target->portalflood[j >> 3] & ( 1 << ( j & 7 ) ) ) ) {
				continue;
			}
			if ( !( portal->portalflood[j >> 3] & ( 1 << ( j & 7 ) ) ) ) {
				continue;
			}
			for ( k = 0; k < numseperators; k++ )
			{
				//
				d = DotProduct( p->origin, seperators[k].normal ) - seperators[k].dist;
				//if completely at the back of the seperator plane
				if ( d < -p->radius + ON_EPSILON ) {
					break;
				}
				w = p->winding;
				for ( n = 0; n < w->numpoints; n++ )
				{
					d = DotProduct( w->points[n], seperators[k].normal ) - seperators[k].dist;
					//if at the front of the seperator
					if ( d > ON_EPSILON ) {
						break;
					}
				}
				//if no points are at the front of the seperator
				if ( n >= w->numpoints ) {
					break;
				}
			}
			if ( k < numseperators ) {
				continue;
			}

			/* explitive deleted */


			/* ydnar: prefer correctness to stack overflow  */
			//% memcpy( &in, p->winding, (int)((fixedWinding_t *)0)->points[p->winding->numpoints] );
			if ( p->winding->numpoints <= MAX_POINTS_ON_FIXED_WINDING ) {
				memcpy( &in, p->winding, (size_t) &( ( (fixedWinding_t*) 0 )->points[ p->winding->numpoints ] ) );
			}
			else{
				memcpy( &in, p->winding, sizeof( fixedWinding_t ) );
			}


			for ( k = 0; k < numseperators; k++ )
			{
				/* ydnar: this is a shitty crutch */
				if ( in.numpoints > MAX_POINTS_ON_FIXED_WINDING ) {
					//% Sys_Printf( "[%d]", p->winding->numpoints );
					in.numpoints = MAX_POINTS_ON_FIXED_WINDING;
				}

				res = PassageChopWinding( &in, &out, &seperators[ k ] );
				if ( res == &out ) {
					memcpy( &in, &out, sizeof( fixedWinding_t ) );
				}


				if ( res == NULL ) {
					break;
				}
			}
			if ( k < numseperators ) {
				continue;
			}
			passage->cansee[j >> 3] |= ( 1 << ( j & 7 ) );
			numsee++;
		}
	}
}

void PassageMemory( void ){
	int i, j, totalmem, totalportals;
	vportal_t *portal, *target;
	leaf_t *leaf;

	totalmem = 0;
	totalportals = 0;
	for ( i = 0; i < numportals; i++ )
	{
		portal = sorted_portals[i];
		if ( portal->removed ) {
			continue;
		}
		leaf = &leafs[portal->leaf];
		for ( j = 0; j < leaf->numportals; j++ )
		{
			target = leaf->portals[j];
			if ( target->removed ) {
				continue;
			}
			totalmem += sizeof( passage_t ) + portalbytes;
			totalportals++;
		}
	}
	Sys_Printf( "%7i average number of passages per leaf\n", totalportals / numportals );
	Sys_Printf( "%7i MB required passage memory\n", totalmem >> 10 >> 10 );
}

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

   This is a rough first-order aproximation that is used to trivially reject some
   of the final calculations.


   Calculates portalfront and portalflood bit vectors

   thinking about:

   typedef struct passage_s
   {
    struct passage_s	*next;
    struct portal_s		*to;
    stryct sep_s		*seperators;
    byte				*mightsee;
   } passage_t;

   typedef struct portal_s
   {
    struct passage_s	*passages;
    int					leaf;		// leaf portal faces into
   } portal_s;

   leaf = portal->leaf
   clear
   for all portals


   calc portal visibility
    clear bit vector
    for all passages
        passage visibility


   for a portal to be visible to a passage, it must be on the front of
   all seperating planes, and both portals must be behind the new portal

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

int c_flood, c_vis;


/*
   ==================
   SimpleFlood

   ==================
 */
void SimpleFlood( vportal_t *srcportal, int leafnum ){
	int i;
	leaf_t  *leaf;
	vportal_t   *p;
	int pnum;

	leaf = &leafs[leafnum];

	for ( i = 0 ; i < leaf->numportals ; i++ )
	{
		p = leaf->portals[i];
		if ( p->removed ) {
			continue;
		}
		pnum = p - portals;
		if ( !( srcportal->portalfront[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) ) {
			continue;
		}

		if ( srcportal->portalflood[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) {
			continue;
		}

		srcportal->portalflood[pnum >> 3] |= ( 1 << ( pnum & 7 ) );

		SimpleFlood( srcportal, p->leaf );
	}
}

/*
   ==============
   BasePortalVis
   ==============
 */
void BasePortalVis( int portalnum ){
	int j, k;
	vportal_t   *tp, *p;
	float d;
	fixedWinding_t  *w;
	vec3_t dir;


	p = portals + portalnum;

	if ( p->removed ) {
		return;
	}

	p->portalfront = safe_malloc( portalbytes );
	memset( p->portalfront, 0, portalbytes );

	p->portalflood = safe_malloc( portalbytes );
	memset( p->portalflood, 0, portalbytes );

	p->portalvis = safe_malloc( portalbytes );
	memset( p->portalvis, 0, portalbytes );

	for ( j = 0, tp = portals ; j < numportals * 2 ; j++, tp++ )
	{
		if ( j == portalnum ) {
			continue;
		}
		if ( tp->removed ) {
			continue;
		}

		/* ydnar: this is old farplane vis code from mre */
		/*
		   if (farplanedist >= 0)
		   {
		    vec3_t dir;
		    VectorSubtract(p->origin, tp->origin, dir);
		    if (VectorLength(dir) > farplanedist - p->radius - tp->radius)
		        continue;
		   }
		 */

		/* ydnar: this is known-to-be-working farplane code */
		if ( !p->sky && !tp->sky && farPlaneDist > 0.0f ) {
			VectorSubtract( p->origin, tp->origin, dir );
			if ( VectorLength( dir ) - p->radius - tp->radius > farPlaneDist ) {
				continue;
			}
		}


		w = tp->winding;
		for ( k = 0 ; k < w->numpoints ; k++ )
		{
			d = DotProduct( w->points[k], p->plane.normal )
				- p->plane.dist;
			if ( d > ON_EPSILON ) {
				break;
			}
		}
		if ( k == w->numpoints ) {
			continue;   // no points on front

		}
		w = p->winding;
		for ( k = 0 ; k < w->numpoints ; k++ )
		{
			d = DotProduct( w->points[k], tp->plane.normal )
				- tp->plane.dist;
			if ( d < -ON_EPSILON ) {
				break;
			}
		}
		if ( k == w->numpoints ) {
			continue;   // no points on front

		}
		p->portalfront[j >> 3] |= ( 1 << ( j & 7 ) );
	}

	SimpleFlood( p, p->leaf );

	p->nummightsee = CountBits( p->portalflood, numportals * 2 );
//	Sys_Printf ("portal %i: %i mightsee\n", portalnum, p->nummightsee);
	c_flood += p->nummightsee;
}





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

   This is a second order aproximation

   Calculates portalvis bit vector

   WAAAAAAY too slow.

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

/*
   ==================
   RecursiveLeafBitFlow

   ==================
 */
void RecursiveLeafBitFlow( int leafnum, byte *mightsee, byte *cansee ){
	vportal_t   *p;
	leaf_t      *leaf;
	int i, j;
	long more;
	int pnum;
	byte newmight[MAX_PORTALS / 8];

	leaf = &leafs[leafnum];

	// check all portals for flowing into other leafs
	for ( i = 0 ; i < leaf->numportals ; i++ )
	{
		p = leaf->portals[i];
		if ( p->removed ) {
			continue;
		}
		pnum = p - portals;

		// if some previous portal can't see it, skip
		if ( !( mightsee[pnum >> 3] & ( 1 << ( pnum & 7 ) ) ) ) {
			continue;
		}

		// if this portal can see some portals we mightsee, recurse
		more = 0;
		for ( j = 0 ; j < portallongs ; j++ )
		{
			( (long *)newmight )[j] = ( (long *)mightsee )[j]
									  & ( (long *)p->portalflood )[j];
			more |= ( (long *)newmight )[j] & ~( (long *)cansee )[j];
		}

		if ( !more ) {
			continue;   // can't see anything new

		}
		cansee[pnum >> 3] |= ( 1 << ( pnum & 7 ) );

		RecursiveLeafBitFlow( p->leaf, newmight, cansee );
	}
}

/*
   ==============
   BetterPortalVis
   ==============
 */
void BetterPortalVis( int portalnum ){
	vportal_t   *p;

	p = portals + portalnum;

	if ( p->removed ) {
		return;
	}

	RecursiveLeafBitFlow( p->leaf, p->portalflood, p->portalvis );

	// build leaf vis information
	p->nummightsee = CountBits( p->portalvis, numportals * 2 );
	c_vis += p->nummightsee;
}