code/qcommon/cm_patch.cpp

/*
===========================================================================
Copyright (C) 1999 - 2005, Id Software, Inc.
Copyright (C) 2000 - 2013, Raven Software, Inc.
Copyright (C) 2001 - 2013, Activision, Inc.
Copyright (C) 2013 - 2015, OpenJK contributors

This file is part of the OpenJK source code.

OpenJK is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.

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, see <http://www.gnu.org/licenses/>.
===========================================================================
*/

#include "cm_local.h"
#include "cm_patch.h"

//#define	CULL_BBOX

/*

This file does not reference any globals, and has these entry points:

void CM_ClearLevelPatches( void );
struct patchCollide_s	*CM_GeneratePatchCollide( int width, int height, const vec3_t *points );
void CM_TraceThroughPatchCollide( traceWork_t *tw, const struct patchCollide_s *pc );
qboolean CM_PositionTestInPatchCollide( traceWork_t *tw, const struct patchCollide_s *pc );
void CM_DrawDebugSurface( void (*drawPoly)(int color, int numPoints, flaot *points) );


Issues for collision against curved surfaces:

Surface edges need to be handled differently than surface planes

Plane expansion causes raw surfaces to expand past expanded bounding box

Position test of a volume against a surface is tricky.

Position test of a point against a surface is not well defined, because the surface has no volume.


Tracing leading edge points instead of volumes?
Position test by tracing corner to corner? (8*7 traces -- ouch)

coplanar edges
triangulated patches
degenerate patches

  endcaps
  degenerate

WARNING: this may misbehave with meshes that have rows or columns that only
degenerate a few triangles.  Completely degenerate rows and columns are handled
properly.
*/

/*
#define	MAX_FACETS			1024
#define	MAX_PATCH_PLANES	2048

typedef struct {
	float	plane[4];
	int		signbits;		// signx + (signy<<1) + (signz<<2), used as lookup during collision
} patchPlane_t;

typedef struct {
	int			surfacePlane;
	int			numBorders;		// 3 or four + 6 axial bevels + 4 or 3 * 4 edge bevels
	int			borderPlanes[4+6+16];
	int			borderInward[4+6+16];
	qboolean	borderNoAdjust[4+6+16];
} facet_t;

typedef struct patchCollide_s {
	vec3_t	bounds[2];
	int		numPlanes;			// surface planes plus edge planes
	patchPlane_t	*planes;
	int		numFacets;
	facet_t	*facets;
} patchCollide_t;


#define	MAX_GRID_SIZE	129

typedef struct {
	int			width;
	int			height;
	qboolean	wrapWidth;
	qboolean	wrapHeight;
	vec3_t	points[MAX_GRID_SIZE][MAX_GRID_SIZE];	// [width][height]
} cGrid_t;

#define	SUBDIVIDE_DISTANCE	16	//4	// never more than this units away from curve
#define	PLANE_TRI_EPSILON	0.1
#define	WRAP_POINT_EPSILON	0.1
*/

#define ADDBEVELS

int	c_totalPatchBlocks;
int	c_totalPatchSurfaces;
int	c_totalPatchEdges;

static const patchCollide_t	*debugPatchCollide;
static const facet_t		*debugFacet;
static qboolean		debugBlock;
static vec3_t		debugBlockPoints[4];

/*
=================
CM_ClearLevelPatches
=================
*/
void CM_ClearLevelPatches( void ) {
	debugPatchCollide = NULL;
	debugFacet = NULL;
}

/*
=================
CM_SignbitsForNormal
=================
*/
static int CM_SignbitsForNormal( vec3_t normal ) {
	int	bits, j;

	bits = 0;
	for (j=0 ; j<3 ; j++) {
		if ( normal[j] < 0 ) {
			bits |= 1<<j;
		}
	}
	return bits;
}

/*
=====================
CM_PlaneFromPoints

Returns false if the triangle is degenrate.
The normal will point out of the clock for clockwise ordered points
=====================
*/
static qboolean CM_PlaneFromPoints( vec4_t plane, vec3_t a, vec3_t b, vec3_t c ) {
	vec3_t	d1, d2;

	VectorSubtract( b, a, d1 );
	VectorSubtract( c, a, d2 );
	CrossProduct( d2, d1, plane );
	if ( VectorNormalize( plane ) == 0 ) {
		return qfalse;
	}

	plane[3] = DotProduct( a, plane );
	return qtrue;
}


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

GRID SUBDIVISION

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

/*
=================
CM_NeedsSubdivision

Returns true if the given quadratic curve is not flat enough for our
collision detection purposes
=================
*/
static qboolean	CM_NeedsSubdivision( vec3_t a, vec3_t b, vec3_t c ) {
	vec3_t		cmid;
	vec3_t		lmid;
	vec3_t		delta;
	float		dist;
	int			i;

	// calculate the linear midpoint
	for ( i = 0 ; i < 3 ; i++ ) {
		lmid[i] = 0.5*(a[i] + c[i]);
	}

	// calculate the exact curve midpoint
	for ( i = 0 ; i < 3 ; i++ ) {
		cmid[i] = 0.5 * ( 0.5*(a[i] + b[i]) + 0.5*(b[i] + c[i]) );
	}

	// see if the curve is far enough away from the linear mid
	VectorSubtract( cmid, lmid, delta );
	dist = VectorLengthSquared( delta );

	return (qboolean)(dist >= (SUBDIVIDE_DISTANCE * SUBDIVIDE_DISTANCE));
}

/*
===============
CM_Subdivide

a, b, and c are control points.
the subdivided sequence will be: a, out1, out2, out3, c
===============
*/
static void CM_Subdivide( vec3_t a, vec3_t b, vec3_t c, vec3_t out1, vec3_t out2, vec3_t out3 ) {
	int		i;

	for ( i = 0 ; i < 3 ; i++ ) {
		out1[i] = 0.5 * (a[i] + b[i]);
		out3[i] = 0.5 * (b[i] + c[i]);
		out2[i] = 0.5 * (out1[i] + out3[i]);
	}
}

/*
=================
CM_TransposeGrid

Swaps the rows and columns in place
=================
*/
static void CM_TransposeGrid( cGrid_t *grid ) {
	int			i, j, l;
	vec3_t		temp;
	qboolean	tempWrap;

	if ( grid->width > grid->height ) {
		for ( i = 0 ; i < grid->height ; i++ ) {
			for ( j = i + 1 ; j < grid->width ; j++ ) {
				if ( j < grid->height ) {
					// swap the value
					VectorCopy( grid->points[i][j], temp );
					VectorCopy( grid->points[j][i], grid->points[i][j] );
					VectorCopy( temp, grid->points[j][i] );
				} else {
					// just copy
					VectorCopy( grid->points[j][i], grid->points[i][j] );
				}
			}
		}
	} else {
		for ( i = 0 ; i < grid->width ; i++ ) {
			for ( j = i + 1 ; j < grid->height ; j++ ) {
				if ( j < grid->width ) {
					// swap the value
					VectorCopy( grid->points[j][i], temp );
					VectorCopy( grid->points[i][j], grid->points[j][i] );
					VectorCopy( temp, grid->points[i][j] );
				} else {
					// just copy
					VectorCopy( grid->points[i][j], grid->points[j][i] );
				}
			}
		}
	}

	l = grid->width;
	grid->width = grid->height;
	grid->height = l;

	tempWrap = grid->wrapWidth;
	grid->wrapWidth = grid->wrapHeight;
	grid->wrapHeight = tempWrap;
}

/*
===================
CM_SetGridWrapWidth

If the left and right columns are exactly equal, set grid->wrapWidth qtrue
===================
*/
static void CM_SetGridWrapWidth( cGrid_t *grid ) {
	int		i, j;
	float	d;

	for ( i = 0 ; i < grid->height ; i++ ) {
		for ( j = 0 ; j < 3 ; j++ ) {
			d = grid->points[0][i][j] - grid->points[grid->width-1][i][j];
			if ( d < -WRAP_POINT_EPSILON || d > WRAP_POINT_EPSILON ) {
				break;
			}
		}
		if ( j != 3 ) {
			break;
		}
	}
	if ( i == grid->height ) {
		grid->wrapWidth = qtrue;
	} else {
		grid->wrapWidth = qfalse;
	}
}


/*
=================
CM_SubdivideGridColumns

Adds columns as necessary to the grid until
all the aproximating points are within SUBDIVIDE_DISTANCE
from the true curve
=================
*/
static void CM_SubdivideGridColumns( cGrid_t *grid ) {
	int		i, j, k;

	for ( i = 0 ; i < grid->width - 2 ;  ) {
		// grid->points[i][x] is an interpolating control point
		// grid->points[i+1][x] is an aproximating control point
		// grid->points[i+2][x] is an interpolating control point

		//
		// first see if we can collapse the aproximating collumn away
		//
		for ( j = 0 ; j < grid->height ; j++ ) {
			if ( CM_NeedsSubdivision( grid->points[i][j], grid->points[i+1][j], grid->points[i+2][j] ) ) {
				break;
			}
		}
		if ( j == grid->height ) {
			// all of the points were close enough to the linear midpoints
			// that we can collapse the entire column away
			for ( j = 0 ; j < grid->height ; j++ ) {
				// remove the column
				for ( k = i + 2 ; k < grid->width ; k++ ) {
					VectorCopy( grid->points[k][j], grid->points[k-1][j] );
				}
			}

			grid->width--;

			// go to the next curve segment
			i++;
			continue;
		}

		//
		// we need to subdivide the curve
		//
		for ( j = 0 ; j < grid->height ; j++ ) {
			vec3_t	prev, mid, next;

			// save the control points now
			VectorCopy( grid->points[i][j], prev );
			VectorCopy( grid->points[i+1][j], mid );
			VectorCopy( grid->points[i+2][j], next );

			// make room for two additional columns in the grid
			// columns i+1 will be replaced, column i+2 will become i+4
			// i+1, i+2, and i+3 will be generated
			for ( k = grid->width - 1 ; k > i + 1 ; k-- ) {
				VectorCopy( grid->points[k][j], grid->points[k+2][j] );
			}

			// generate the subdivided points
			CM_Subdivide( prev, mid, next, grid->points[i+1][j], grid->points[i+2][j], grid->points[i+3][j] );
		}

		grid->width += 2;

		// the new aproximating point at i+1 may need to be removed
		// or subdivided farther, so don't advance i
	}
}


#define	POINT_EPSILON	0.1
/*
======================
CM_ComparePoints
======================
*/
static qboolean CM_ComparePoints( float *a, float *b ) {
	float		d;

	d = a[0] - b[0];
	if ( d < -POINT_EPSILON || d > POINT_EPSILON ) {
		return qfalse;
	}
	d = a[1] - b[1];
	if ( d < -POINT_EPSILON || d > POINT_EPSILON ) {
		return qfalse;
	}
	d = a[2] - b[2];
	if ( d < -POINT_EPSILON || d > POINT_EPSILON ) {
		return qfalse;
	}
	return qtrue;
}

/*
=================
CM_RemoveDegenerateColumns

If there are any identical columns, remove them
=================
*/
static void CM_RemoveDegenerateColumns( cGrid_t *grid ) {
	int		i, j, k;

	for ( i = 0 ; i < grid->width - 1 ; i++ ) {
		for ( j = 0 ; j < grid->height ; j++ ) {
			if ( !CM_ComparePoints( grid->points[i][j], grid->points[i+1][j] ) ) {
				break;
			}
		}

		if ( j != grid->height ) {
			continue;	// not degenerate
		}

		for ( j = 0 ; j < grid->height ; j++ ) {
			// remove the column
			for ( k = i + 2 ; k < grid->width ; k++ ) {
				VectorCopy( grid->points[k][j], grid->points[k-1][j] );
			}
		}
		grid->width--;

		// check against the next column
		i--;
	}
}

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

PATCH COLLIDE GENERATION

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

static	int				numPlanes;
static	patchPlane_t	planes[MAX_PATCH_PLANES];

//static	int				numFacets;
// static	facet_t			facets[MAX_PATCH_PLANES]; //maybe MAX_FACETS ??
//static	facet_t			facets[MAX_FACETS];	// Switched to MAX_FACETS = VV_FIXME, allocate these only during use
static	facet_t			*facets = NULL;

#define	NORMAL_EPSILON	0.00015
#define	DIST_EPSILON	0.0235

int CM_PlaneEqual(patchPlane_t *p, float plane[4], int *flipped) {
	float invplane[4];

	if (
	   Q_fabs(p->plane[0] - plane[0]) < NORMAL_EPSILON
	&& Q_fabs(p->plane[1] - plane[1]) < NORMAL_EPSILON
	&& Q_fabs(p->plane[2] - plane[2]) < NORMAL_EPSILON
	&& Q_fabs(p->plane[3] - plane[3]) < DIST_EPSILON )
	{
		*flipped = qfalse;
		return qtrue;
	}

	VectorNegate(plane, invplane);
	invplane[3] = -plane[3];

	if (
	   Q_fabs(p->plane[0] - invplane[0]) < NORMAL_EPSILON
	&& Q_fabs(p->plane[1] - invplane[1]) < NORMAL_EPSILON
	&& Q_fabs(p->plane[2] - invplane[2]) < NORMAL_EPSILON
	&& Q_fabs(p->plane[3] - invplane[3]) < DIST_EPSILON )
	{
		*flipped = qtrue;
		return qtrue;
	}

	return qfalse;
}

void CM_SnapVector(vec3_t normal) {
	int		i;

	for (i=0 ; i<3 ; i++)
	{
		if ( Q_fabs(normal[i] - 1) < NORMAL_EPSILON )
		{
			VectorClear (normal);
			normal[i] = 1;
			break;
		}
		if ( Q_fabs(normal[i] - -1) < NORMAL_EPSILON )
		{
			VectorClear (normal);
			normal[i] = -1;
			break;
		}
	}
}

int CM_FindPlane2(float plane[4], int *flipped) {
	int i;

	// see if the points are close enough to an existing plane
	for ( i = 0 ; i < numPlanes ; i++ ) {
		if (CM_PlaneEqual(&planes[i], plane, flipped)) return i;
	}

	// add a new plane
	if ( numPlanes == MAX_PATCH_PLANES ) {
		Com_Error( ERR_DROP, "MAX_PATCH_PLANES reached (%d)", MAX_PATCH_PLANES );
	}

	VectorCopy4( plane, planes[numPlanes].plane );
	planes[numPlanes].signbits = CM_SignbitsForNormal( plane );

	numPlanes++;

	*flipped = qfalse;

	return numPlanes-1;
}

/*
==================
CM_FindPlane
==================
*/
static int CM_FindPlane( float *p1, float *p2, float *p3 ) {
	float	plane[4];
	int		i;
	float	d;

	if ( !CM_PlaneFromPoints( plane, p1, p2, p3 ) ) {
		return -1;
	}

	// see if the points are close enough to an existing plane
	for ( i = 0 ; i < numPlanes ; i++ ) {
		if ( DotProduct( plane, planes[i].plane ) < 0 ) {
			continue;	// allow backwards planes?
		}

		d = DotProduct( p1, planes[i].plane ) - planes[i].plane[3];
		if ( d < -PLANE_TRI_EPSILON || d > PLANE_TRI_EPSILON ) {
			continue;
		}

		d = DotProduct( p2, planes[i].plane ) - planes[i].plane[3];
		if ( d < -PLANE_TRI_EPSILON || d > PLANE_TRI_EPSILON ) {
			continue;
		}

		d = DotProduct( p3, planes[i].plane ) - planes[i].plane[3];
		if ( d < -PLANE_TRI_EPSILON || d > PLANE_TRI_EPSILON ) {
			continue;
		}

		// found it
		return i;
	}

	// add a new plane
	if ( numPlanes == MAX_PATCH_PLANES ) {
		Com_Error( ERR_DROP, "MAX_PATCH_PLANES" );
	}

	VectorCopy4( plane, planes[numPlanes].plane );
	planes[numPlanes].signbits = CM_SignbitsForNormal( plane );

	numPlanes++;

	return numPlanes-1;
}


/*
==================
CM_PointOnPlaneSide
==================
*/
static int CM_PointOnPlaneSide( float *p, int planeNum ) {
	float	*plane;
	float	d;

	if ( planeNum == -1 ) {
		return SIDE_ON;
	}
	plane = planes[ planeNum ].plane;

	d = DotProduct( p, plane ) - plane[3];

	if ( d > PLANE_TRI_EPSILON ) {
		return SIDE_FRONT;
	}

	if ( d < -PLANE_TRI_EPSILON ) {
		return SIDE_BACK;
	}

	return SIDE_ON;
}


static int	CM_GridPlane( int gridPlanes[CM_MAX_GRID_SIZE][CM_MAX_GRID_SIZE][2], int i, int j, int tri ) {
	int		p;

	p = gridPlanes[i][j][tri];
	if ( p != -1 ) {
		return p;
	}
	p = gridPlanes[i][j][!tri];
	if ( p != -1 ) {
		return p;
	}

	// should never happen
	Com_Printf( "WARNING: CM_GridPlane unresolvable\n" );
	return -1;
}

/*
==================
CM_EdgePlaneNum
==================
*/
static int CM_EdgePlaneNum( cGrid_t *grid, int gridPlanes[CM_MAX_GRID_SIZE][CM_MAX_GRID_SIZE][2], int i, int j, int k ) {
	float	*p1, *p2;
	vec3_t		up;
	int			p;

	switch ( k ) {
	case 0:	// top border
		p1 = grid->points[i][j];
		p2 = grid->points[i+1][j];
		p = CM_GridPlane( gridPlanes, i, j, 0 );
		if ( p == -1 ) {
			return -1;
		}
		VectorMA( p1, 4, planes[ p ].plane, up );
		return CM_FindPlane( p1, p2, up );

	case 2:	// bottom border
		p1 = grid->points[i][j+1];
		p2 = grid->points[i+1][j+1];
		p = CM_GridPlane( gridPlanes, i, j, 1 );
		if ( p == -1 ) {
			return -1;
		}
		VectorMA( p1, 4, planes[ p ].plane, up );
		return CM_FindPlane( p2, p1, up );

	case 3: // left border
		p1 = grid->points[i][j];
		p2 = grid->points[i][j+1];
		p = CM_GridPlane( gridPlanes, i, j, 1 );
		if ( p == -1 ) {
			return -1;
		}
		VectorMA( p1, 4, planes[ p ].plane, up );
		return CM_FindPlane( p2, p1, up );

	case 1:	// right border
		p1 = grid->points[i+1][j];
		p2 = grid->points[i+1][j+1];
		p = CM_GridPlane( gridPlanes, i, j, 0 );
		if ( p == -1 ) {
			return -1;
		}
		VectorMA( p1, 4, planes[ p ].plane, up );
		return CM_FindPlane( p1, p2, up );

	case 4:	// diagonal out of triangle 0
		p1 = grid->points[i+1][j+1];
		p2 = grid->points[i][j];
		p = CM_GridPlane( gridPlanes, i, j, 0 );
		if ( p == -1 ) {
			return -1;
		}
		VectorMA( p1, 4, planes[ p ].plane, up );
		return CM_FindPlane( p1, p2, up );

	case 5:	// diagonal out of triangle 1
		p1 = grid->points[i][j];
		p2 = grid->points[i+1][j+1];
		p = CM_GridPlane( gridPlanes, i, j, 1 );
		if ( p == -1 ) {
			return -1;
		}
		VectorMA( p1, 4, planes[ p ].plane, up );
		return CM_FindPlane( p1, p2, up );

	}

	Com_Error( ERR_DROP, "CM_EdgePlaneNum: bad k" );
	return -1;
}

/*
===================
CM_SetBorderInward
===================
*/
static void CM_SetBorderInward( facet_t *facet, cGrid_t *grid, int gridPlanes[CM_MAX_GRID_SIZE][CM_MAX_GRID_SIZE][2],
						  int i, int j, int which ) {
	int		k, l;
	float	*points[4];
	int		numPoints;

	switch ( which ) {
	case -1:
		points[0] = grid->points[i][j];
		points[1] = grid->points[i+1][j];
		points[2] = grid->points[i+1][j+1];
		points[3] = grid->points[i][j+1];
		numPoints = 4;
		break;
	case 0:
		points[0] = grid->points[i][j];
		points[1] = grid->points[i+1][j];
		points[2] = grid->points[i+1][j+1];
		numPoints = 3;
		break;
	case 1:
		points[0] = grid->points[i+1][j+1];
		points[1] = grid->points[i][j+1];
		points[2] = grid->points[i][j];
		numPoints = 3;
		break;
	default:
		Com_Error( ERR_FATAL, "CM_SetBorderInward: bad parameter" );
		numPoints = 0;
		break;
	}

	for ( k = 0 ; k < facet->numBorders ; k++ ) {
		int		front, back;

		front = 0;
		back = 0;

		for ( l = 0 ; l < numPoints ; l++ ) {
			int		side;

			side = CM_PointOnPlaneSide( points[l], facet->borderPlanes[k] );
			if ( side == SIDE_FRONT ) {
				front++;
			} if ( side == SIDE_BACK ) {
				back++;
			}
		}

		if ( front && !back ) {
			facet->borderInward[k] = qtrue;
		} else if ( back && !front ) {
			facet->borderInward[k] = qfalse;
		} else if ( !front && !back ) {
			// flat side border
			facet->borderPlanes[k] = -1;
		} else {
			// bisecting side border
			Com_DPrintf( "WARNING: CM_SetBorderInward: mixed plane sides\n" );
			facet->borderInward[k] = qfalse;
			if ( !debugBlock ) {
				debugBlock = qtrue;
				VectorCopy( grid->points[i][j], debugBlockPoints[0] );
				VectorCopy( grid->points[i+1][j], debugBlockPoints[1] );
				VectorCopy( grid->points[i+1][j+1], debugBlockPoints[2] );
				VectorCopy( grid->points[i][j+1], debugBlockPoints[3] );
			}
		}
	}
}

/*
==================
CM_ValidateFacet

If the facet isn't bounded by its borders, we screwed up.
==================
*/
static qboolean CM_ValidateFacet( facet_t *facet ) {
	float		plane[4];
	int			j;
	winding_t	*w;
	vec3_t		bounds[2];

	if ( facet->surfacePlane == -1 ) {
		return qfalse;
	}

	VectorCopy4( planes[ facet->surfacePlane ].plane, plane );
	w = BaseWindingForPlane( plane,  plane[3] );
	for ( j = 0 ; j < facet->numBorders && w ; j++ ) {
		if ( facet->borderPlanes[j] == -1 ) {
			FreeWinding(w);
			return qfalse;
		}
		VectorCopy4( planes[ facet->borderPlanes[j] ].plane, plane );
		if ( !facet->borderInward[j] ) {
			VectorSubtract( vec3_origin, plane, plane );
			plane[3] = -plane[3];
		}
		ChopWindingInPlace( &w, plane, plane[3], 0.1f );
	}

	if ( !w ) {
		return qfalse;		// winding was completely chopped away
	}

	// see if the facet is unreasonably large
	WindingBounds( w, bounds[0], bounds[1] );
	FreeWinding( w );

	for ( j = 0 ; j < 3 ; j++ ) {
		if ( bounds[1][j] - bounds[0][j] > MAX_MAP_BOUNDS ) {
			return qfalse;		// we must be missing a plane
		}
		if ( bounds[0][j] >= MAX_MAP_BOUNDS ) {
			return qfalse;
		}
		if ( bounds[1][j] <= -MAX_MAP_BOUNDS ) {
			return qfalse;
		}
	}
	return qtrue;		// winding is fine
}

/*
==================
CM_AddFacetBevels
==================
*/
void CM_AddFacetBevels( facet_t *facet ) {

	int i, j, k, l;
	int axis, dir, order, flipped;
	float plane[4], d, newplane[4];
	winding_t *w, *w2;
	vec3_t mins, maxs, vec, vec2;

#ifndef ADDBEVELS
	return;
#endif

	VectorCopy4( planes[ facet->surfacePlane ].plane, plane );

	w = BaseWindingForPlane( plane,  plane[3] );
	for ( j = 0 ; j < facet->numBorders && w ; j++ ) {
		if (facet->borderPlanes[j] == facet->surfacePlane) continue;
		VectorCopy4( planes[ facet->borderPlanes[j] ].plane, plane );

		if ( !facet->borderInward[j] ) {
			VectorSubtract( vec3_origin, plane, plane );
			plane[3] = -plane[3];
		}

		ChopWindingInPlace( &w, plane, plane[3], 0.1f );
	}
	if ( !w ) {
		return;
	}

	WindingBounds(w, mins, maxs);

	// add the axial planes
	order = 0;
	for ( axis = 0 ; axis < 3 ; axis++ )
	{
		for ( dir = -1 ; dir <= 1 ; dir += 2, order++ )
		{
			VectorClear(plane);
			plane[axis] = dir;
			if (dir == 1) {
				plane[3] = maxs[axis];
			}
			else {
				plane[3] = -mins[axis];
			}
			//if it's the surface plane
			if (CM_PlaneEqual(&planes[facet->surfacePlane], plane, &flipped)) {
				continue;
			}
			// see if the plane is allready present
			for ( i = 0 ; i < facet->numBorders ; i++ ) {
				if (CM_PlaneEqual(&planes[facet->borderPlanes[i]], plane, &flipped))
					break;
			}

			if ( i == facet->numBorders ) {
				if (facet->numBorders > 4 + 6 + 16) Com_Printf(S_COLOR_RED"ERROR: too many bevels\n");
				facet->borderPlanes[facet->numBorders] = CM_FindPlane2(plane, &flipped);
				facet->borderNoAdjust[facet->numBorders] = qfalse;
				facet->borderInward[facet->numBorders] = flipped;
				facet->numBorders++;
			}
		}
	}
	//
	// add the edge bevels
	//
	// test the non-axial plane edges
	for ( j = 0 ; j < w->numpoints ; j++ )
	{
		k = (j+1)%w->numpoints;
		VectorSubtract (w->p[j], w->p[k], vec);
		//if it's a degenerate edge
		if (VectorNormalize (vec) < 0.5)
			continue;
		CM_SnapVector(vec);
		for ( k = 0; k < 3 ; k++ )
			if ( vec[k] == -1 || vec[k] == 1 )
				break;	// axial
		if ( k < 3 )
			continue;	// only test non-axial edges

		// try the six possible slanted axials from this edge
		for ( axis = 0 ; axis < 3 ; axis++ )
		{
			for ( dir = -1 ; dir <= 1 ; dir += 2 )
			{
				// construct a plane
				VectorClear (vec2);
				vec2[axis] = dir;
				CrossProduct (vec, vec2, plane);
				if (VectorNormalize (plane) < 0.5)
					continue;
				plane[3] = DotProduct (w->p[j], plane);

				// if all the points of the facet winding are
				// behind this plane, it is a proper edge bevel
				for ( l = 0 ; l < w->numpoints ; l++ )
				{
					d = DotProduct (w->p[l], plane) - plane[3];
					if (d > 0.1)
						break;	// point in front
				}
				if ( l < w->numpoints )
					continue;

				//if it's the surface plane
				if (CM_PlaneEqual(&planes[facet->surfacePlane], plane, &flipped)) {
					continue;
				}
				// see if the plane is allready present
				for ( i = 0 ; i < facet->numBorders ; i++ ) {
					if (CM_PlaneEqual(&planes[facet->borderPlanes[i]], plane, &flipped)) {
							break;
					}
				}

				if ( i == facet->numBorders ) {
					if (facet->numBorders > 4 + 6 + 16) Com_Printf(S_COLOR_RED"ERROR: too many bevels\n");
					facet->borderPlanes[facet->numBorders] = CM_FindPlane2(plane, &flipped);

					for ( k = 0 ; k < facet->numBorders ; k++ ) {
						if (facet->borderPlanes[facet->numBorders] ==
							facet->borderPlanes[k]) Com_Printf("WARNING: bevel plane already used\n");
					}

					facet->borderNoAdjust[facet->numBorders] = qfalse;
					facet->borderInward[facet->numBorders] = flipped;
					//
					w2 = CopyWinding(w);
					VectorCopy4(planes[facet->borderPlanes[facet->numBorders]].plane, newplane);
					if (!facet->borderInward[facet->numBorders])
					{
						VectorNegate(newplane, newplane);
						newplane[3] = -newplane[3];
					} //end if
					ChopWindingInPlace( &w2, newplane, newplane[3], 0.1f );
					if (!w2) {
						Com_DPrintf("WARNING: CM_AddFacetBevels... invalid bevel\n");
						continue;
					}
					else {
						FreeWinding(w2);
					}
					//
					facet->numBorders++;
					//already got a bevel
//					break;
				}
			}
		}
	}
	FreeWinding( w );

#ifndef BSPC
	//add opposite plane
	facet->borderPlanes[facet->numBorders] = facet->surfacePlane;
	facet->borderNoAdjust[facet->numBorders] = qfalse;
	facet->borderInward[facet->numBorders] = qtrue;
	facet->numBorders++;
#endif //BSPC

}


typedef enum {
	EN_TOP,
	EN_RIGHT,
	EN_BOTTOM,
	EN_LEFT
} edgeName_t;


/*
==================
CM_PatchCollideFromGrid
==================
*/
static void CM_PatchCollideFromGrid( cGrid_t *grid, patchCollide_t *pf ) {
	int				i, j;
	float			*p1, *p2, *p3;
	int				gridPlanes[CM_MAX_GRID_SIZE][CM_MAX_GRID_SIZE][2];
	facet_t			*facet;
	int				borders[4];
	qboolean		noAdjust[4];

	int numFacets;
	facets = (facet_t*) Z_Malloc(MAX_FACETS*sizeof(facet_t), TAG_TEMP_WORKSPACE, qfalse);

	numPlanes = 0;
	numFacets = 0;

	// find the planes for each triangle of the grid
	for ( i = 0 ; i < grid->width - 1 ; i++ ) {
		for ( j = 0 ; j < grid->height - 1 ; j++ ) {
			p1 = grid->points[i][j];
			p2 = grid->points[i+1][j];
			p3 = grid->points[i+1][j+1];
			gridPlanes[i][j][0] = CM_FindPlane( p1, p2, p3 );

			p1 = grid->points[i+1][j+1];
			p2 = grid->points[i][j+1];
			p3 = grid->points[i][j];
			gridPlanes[i][j][1] = CM_FindPlane( p1, p2, p3 );
		}
	}

	// create the borders for each facet
	for ( i = 0 ; i < grid->width - 1 ; i++ ) {
		for ( j = 0 ; j < grid->height - 1 ; j++ ) {

			borders[EN_TOP] = -1;
			if ( j > 0 ) {
				borders[EN_TOP] = gridPlanes[i][j-1][1];
			} else if ( grid->wrapHeight ) {
				borders[EN_TOP] = gridPlanes[i][grid->height-2][1];
			}
			noAdjust[EN_TOP] = (qboolean)( borders[EN_TOP] == gridPlanes[i][j][0] );
			if ( borders[EN_TOP] == -1 || noAdjust[EN_TOP] ) {
				borders[EN_TOP] = CM_EdgePlaneNum( grid, gridPlanes, i, j, 0 );
			}

			borders[EN_BOTTOM] = -1;
			if ( j < grid->height - 2 ) {
				borders[EN_BOTTOM] = gridPlanes[i][j+1][0];
			} else if ( grid->wrapHeight ) {
				borders[EN_BOTTOM] = gridPlanes[i][0][0];
			}
			noAdjust[EN_BOTTOM] = (qboolean)( borders[EN_BOTTOM] == gridPlanes[i][j][1] );
			if ( borders[EN_BOTTOM] == -1 || noAdjust[EN_BOTTOM] ) {
				borders[EN_BOTTOM] = CM_EdgePlaneNum( grid, gridPlanes, i, j, 2 );
			}

			borders[EN_LEFT] = -1;
			if ( i > 0 ) {
				borders[EN_LEFT] = gridPlanes[i-1][j][0];
			} else if ( grid->wrapWidth ) {
				borders[EN_LEFT] = gridPlanes[grid->width-2][j][0];
			}
			noAdjust[EN_LEFT] = (qboolean)( borders[EN_LEFT] == gridPlanes[i][j][1] );
			if ( borders[EN_LEFT] == -1 || noAdjust[EN_LEFT] ) {
				borders[EN_LEFT] = CM_EdgePlaneNum( grid, gridPlanes, i, j, 3 );
			}

			borders[EN_RIGHT] = -1;
			if ( i < grid->width - 2 ) {
				borders[EN_RIGHT] = gridPlanes[i+1][j][1];
			} else if ( grid->wrapWidth ) {
				borders[EN_RIGHT] = gridPlanes[0][j][1];
			}
			noAdjust[EN_RIGHT] = (qboolean)( borders[EN_RIGHT] == gridPlanes[i][j][0] );
			if ( borders[EN_RIGHT] == -1 || noAdjust[EN_RIGHT] ) {
				borders[EN_RIGHT] = CM_EdgePlaneNum( grid, gridPlanes, i, j, 1 );
			}

			if ( numFacets == MAX_FACETS ) {
				Com_Error( ERR_DROP, "MAX_FACETS" );
			}
			facet = &facets[numFacets];
			memset( facet, 0, sizeof( *facet ) );

			if ( gridPlanes[i][j][0] == gridPlanes[i][j][1] ) {
				if ( gridPlanes[i][j][0] == -1 ) {
					continue;		// degenrate
				}
				facet->surfacePlane = gridPlanes[i][j][0];
				facet->numBorders = 4;
				facet->borderPlanes[0] = borders[EN_TOP];
				facet->borderNoAdjust[0] = noAdjust[EN_TOP];
				facet->borderPlanes[1] = borders[EN_RIGHT];
				facet->borderNoAdjust[1] = noAdjust[EN_RIGHT];
				facet->borderPlanes[2] = borders[EN_BOTTOM];
				facet->borderNoAdjust[2] = noAdjust[EN_BOTTOM];
				facet->borderPlanes[3] = borders[EN_LEFT];
				facet->borderNoAdjust[3] = noAdjust[EN_LEFT];
				CM_SetBorderInward( facet, grid, gridPlanes, i, j, -1 );
				if ( CM_ValidateFacet( facet ) ) {
					CM_AddFacetBevels( facet );
					numFacets++;
				}
			} else {
				// two seperate triangles
				facet->surfacePlane = gridPlanes[i][j][0];
				facet->numBorders = 3;
				facet->borderPlanes[0] = borders[EN_TOP];
				facet->borderNoAdjust[0] = noAdjust[EN_TOP];
				facet->borderPlanes[1] = borders[EN_RIGHT];
				facet->borderNoAdjust[1] = noAdjust[EN_RIGHT];
				facet->borderPlanes[2] = gridPlanes[i][j][1];
				if ( facet->borderPlanes[2] == -1 ) {
					facet->borderPlanes[2] = borders[EN_BOTTOM];
					if ( facet->borderPlanes[2] == -1 ) {
						facet->borderPlanes[2] = CM_EdgePlaneNum( grid, gridPlanes, i, j, 4 );
					}
				}
 				CM_SetBorderInward( facet, grid, gridPlanes, i, j, 0 );
				if ( CM_ValidateFacet( facet ) ) {
					CM_AddFacetBevels( facet );
					numFacets++;
				}

				if ( numFacets == MAX_FACETS ) {
					Com_Error( ERR_DROP, "MAX_FACETS" );
				}
				facet = &facets[numFacets];
				memset( facet, 0, sizeof( *facet ) );

				facet->surfacePlane = gridPlanes[i][j][1];
				facet->numBorders = 3;
				facet->borderPlanes[0] = borders[EN_BOTTOM];
				facet->borderNoAdjust[0] = noAdjust[EN_BOTTOM];
				facet->borderPlanes[1] = borders[EN_LEFT];
				facet->borderNoAdjust[1] = noAdjust[EN_LEFT];
				facet->borderPlanes[2] = gridPlanes[i][j][0];
				if ( facet->borderPlanes[2] == -1 ) {
					facet->borderPlanes[2] = borders[EN_TOP];
					if ( facet->borderPlanes[2] == -1 ) {
						facet->borderPlanes[2] = CM_EdgePlaneNum( grid, gridPlanes, i, j, 5 );
					}
				}
				CM_SetBorderInward( facet, grid, gridPlanes, i, j, 1 );
				if ( CM_ValidateFacet( facet ) ) {
					CM_AddFacetBevels( facet );
					numFacets++;
				}
			}
		}
	}

	// copy the results out
	pf->numPlanes = numPlanes;
	pf->numFacets = numFacets;
	if (numFacets)
	{
		pf->facets = (facet_t *) Z_Malloc( numFacets * sizeof( *pf->facets ), TAG_BSP, qfalse);
		memcpy( pf->facets, facets, numFacets * sizeof( *pf->facets ) );
	}
	else
	{
		pf->facets = 0;
	}
	pf->planes = (patchPlane_t *) Z_Malloc( numPlanes * sizeof( *pf->planes ), TAG_BSP, qfalse);
	memcpy( pf->planes, planes, numPlanes * sizeof( *pf->planes ) );

	Z_Free(facets);
}

static patchCollide_t *pfScratch = 0;
void CM_PreparePatchCollide(int num)
{
	pfScratch = (patchCollide_t *) Z_Malloc( sizeof( *pfScratch ) * num, TAG_BSP, qfalse );
}

cGrid_t *cm_grid = 0;
void CM_GridAlloc()
{
	if (cm_grid) return;
	cm_grid = (cGrid_t*)Z_Malloc(sizeof(cGrid_t), TAG_TEMP_WORKSPACE, qfalse);
}

void CM_GridDealloc()
{
	Z_Free(cm_grid);
	cm_grid = 0;
}

/*
===================
CM_GeneratePatchCollide

Creates an internal structure that will be used to perform
collision detection with a patch mesh.

Points is packed as concatenated rows.
===================
*/
struct patchCollide_s	*CM_GeneratePatchCollide( int width, int height, vec3_t *points ) {
	patchCollide_t	*pf;
	cGrid_t			grid;
	int				i, j;

	if ( width <= 2 || height <= 2 || !points ) {
		Com_Error( ERR_DROP, "CM_GeneratePatchFacets: bad parameters: (%i, %i, %p)",
			width, height, points );
	}

	if ( !(width & 1) || !(height & 1) ) {
		Com_Error( ERR_DROP, "CM_GeneratePatchFacets: even sizes are invalid for quadratic meshes" );
	}

	if ( width > CM_MAX_GRID_SIZE || height > CM_MAX_GRID_SIZE ) {
		Com_Error( ERR_DROP, "CM_GeneratePatchFacets: source is > CM_MAX_GRID_SIZE" );
	}

	// build a grid
	grid.width = width;
	grid.height = height;
	grid.wrapWidth = qfalse;
	grid.wrapHeight = qfalse;
	for ( i = 0 ; i < width ; i++ ) {
		for ( j = 0 ; j < height ; j++ ) {
			VectorCopy( points[j*width + i], grid.points[i][j] );
		}
	}

	// subdivide the grid
	CM_SetGridWrapWidth( &grid );
	CM_SubdivideGridColumns( &grid );
	CM_RemoveDegenerateColumns( &grid );

	CM_TransposeGrid( &grid );

	CM_SetGridWrapWidth( &grid );
	CM_SubdivideGridColumns( &grid );
	CM_RemoveDegenerateColumns( &grid );

	// we now have a grid of points exactly on the curve
	// the aproximate surface defined by these points will be
	// collided against
	pf = (patchCollide_t *) Z_Malloc( sizeof( *pf ), TAG_BSP, qfalse );
	ClearBounds( pf->bounds[0], pf->bounds[1] );
	for ( i = 0 ; i < grid.width ; i++ ) {
		for ( j = 0 ; j < grid.height ; j++ ) {
			AddPointToBounds( grid.points[i][j], pf->bounds[0], pf->bounds[1] );
		}
	}

	c_totalPatchBlocks += ( grid.width - 1 ) * ( grid.height - 1 );

	// generate a bsp tree for the surface
	CM_PatchCollideFromGrid( &grid, pf );

	// expand by one unit for epsilon purposes
	pf->bounds[0][0] -= 1;
	pf->bounds[0][1] -= 1;
	pf->bounds[0][2] -= 1;

	pf->bounds[1][0] += 1;
	pf->bounds[1][1] += 1;
	pf->bounds[1][2] += 1;

	return pf;
}

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

TRACE TESTING

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

/*
====================
CM_TraceThroughPatchCollide

Modifies tr->tr if any of the facets effect the trace
====================
*/

/*
void CM_TraceThroughPatchCollide( traceWork_t *tw, const struct patchCollide_s *pc )
{
	int i, j, n;
	float d1, d2, offset, planedist, fraction;
	vec3_t v1, v2, normal, point;
	patchPlane_t *planes;
	facet_t	*facet;
	//
	facet = pc->facets;
	for ( i = 0 ; i < pc->numFacets ; i++, facet++ )
	{
		planes = &pc->planes[ facet->surfacePlane ];
		VectorCopy(planes->plane, normal);
		for (n = 0; n < 3; n++)
		{
			if (normal[n] > 0) v1[n] = tw->size[0][n];
			else v1[n] = tw->size[1][n];
		} //end for
		VectorNegate(normal, v2);
		offset = DotProduct(v1, v2);
		//offset = 0;
		//
		planedist = planes->plane[3] + offset;
		//
		d1 = DotProduct( tw->start, normal ) - planedist;
		d2 = DotProduct( tw->end, normal ) - planedist;

		// if completely in front of face, no intersection with the entire patch
		if (d1 > 0 && ( d2 >= SURFACE_CLIP_EPSILON || d2 >= d1 )  ) {
			continue;
		}

		// if it doesn't cross the plane, the plane isn't relevent
		if (d1 <= 0 && d2 <= 0 ) {
			continue;
		}

		// crosses face
		if (d1 > d2) {	// enter
			fraction = (d1-SURFACE_CLIP_EPSILON) / (d1-d2);
			if ( fraction < 0 ) {
				fraction = 0;
			}
			for (j = 0; j < 3; j++)
				point[j] = tw->start[j] + (tw->end[j] - tw->start[j]) * fraction;
		}
		else {
			continue;
		}
		//
		for (j = 0; j < facet->numBorders; j++)
		{
			planes = &pc->planes[ facet->borderPlanes[j] ];
			if (!facet->borderInward[j])
			{
				VectorNegate(planes->plane, normal);
				planedist = -planes->plane[3];
			} //end if
			else
			{
				VectorCopy(planes->plane, normal);
				planedist = planes->plane[3];
			} //end else
			for (n = 0; n < 3; n++)
			{
				if (normal[n] > 0) v1[n] = tw->size[0][n];
				else v1[n] = tw->size[1][n];
			} //end for
			VectorNegate(normal, v2);
			offset = DotProduct(v1, v2);
			//offset = 0;
			planedist -= offset;
			//the hit point should be in front of the (inward facing) border plane
			if (DotProduct(point, normal) - planedist < -ON_EPSILON) break;
		} //end for
		if (j < facet->numBorders) continue;
		//
		if (fraction < tw->trace.fraction)
		{
			debugPatchCollide = pc;
			debugFacet = facet;

			tw->trace.fraction = fraction;
			planes = &pc->planes[ facet->surfacePlane ];
			VectorCopy( planes->plane, tw->trace.plane.normal );
			tw->trace.plane.dist = planes->plane[3];
		} //end if
	} //end for
} //end of the function CM_TraceThroughPatchCollide*/

/*
====================
CM_TracePointThroughPatchCollide

  special case for point traces because the patch collide "brushes" have no volume
====================
*/
void CM_TracePointThroughPatchCollide( traceWork_t *tw, const struct patchCollide_s *pc ) {
	qboolean	frontFacing[MAX_PATCH_PLANES];
	float		intersection[MAX_PATCH_PLANES];
	float		intersect;
	const patchPlane_t	*planes;
	const facet_t	*facet;
	int			i, j, k;
	float		offset;
	float		d1, d2;
#ifndef BSPC
	static cvar_t *cv;
#endif //BSPC

#ifndef BSPC
	if ( !cm_playerCurveClip->integer && !tw->isPoint ) {
		return;		// FIXME: until I get player sized clipping working right
	}
#endif

	if (!pc->numFacets)
	{	//not gonna do anything anyhow?
		return;
	}
	// determine the trace's relationship to all planes
	planes = pc->planes;
	for ( i = 0 ; i < pc->numPlanes ; i++, planes++ ) {
		offset = DotProduct( tw->offsets[ planes->signbits ], planes->plane );
		d1 = DotProduct( tw->start, planes->plane ) - planes->plane[3] + offset;
		d2 = DotProduct( tw->end, planes->plane ) - planes->plane[3] + offset;
		if ( d1 <= 0 ) {
			frontFacing[i] = qfalse;
		} else {
			frontFacing[i] = qtrue;
		}
		if ( d1 == d2 ) {
			intersection[i] = WORLD_SIZE;
		} else {
			intersection[i] = d1 / ( d1 - d2 );
			if ( intersection[i] <= 0 ) {
				intersection[i] = WORLD_SIZE;
			}
		}
	}


	// see if any of the surface planes are intersected
	facet = pc->facets;
	for ( i = 0 ; i < pc->numFacets ; i++, facet++ ) {
		if ( !frontFacing[facet->surfacePlane] ) {
			continue;
		}
		intersect = intersection[facet->surfacePlane];
		if ( intersect < 0 ) {
			continue;		// surface is behind the starting point
		}
		if ( intersect > tw->trace.fraction ) {
			continue;		// already hit something closer
		}
		for ( j = 0 ; j < facet->numBorders ; j++ ) {
			k = facet->borderPlanes[j];
			if ( frontFacing[k] ^ facet->borderInward[j] ) {
				if ( intersection[k] > intersect ) {
					break;
				}
			} else {
				if ( intersection[k] < intersect ) {
					break;
				}
			}
		}
		if ( j == facet->numBorders ) {
			// we hit this facet
#ifndef BSPC
			if (!cv) {
				cv = Cvar_Get( "r_debugSurfaceUpdate", "1", 0 );
			}
			if (cv->integer) {
				debugPatchCollide = pc;
				debugFacet = facet;
			}
#endif //BSPC
			planes = &pc->planes[facet->surfacePlane];

			// calculate intersection with a slight pushoff
			offset = DotProduct( tw->offsets[ planes->signbits ], planes->plane );
			d1 = DotProduct( tw->start, planes->plane ) - planes->plane[3] + offset;
			d2 = DotProduct( tw->end, planes->plane ) - planes->plane[3] + offset;
			tw->trace.fraction = ( d1 - SURFACE_CLIP_EPSILON ) / ( d1 - d2 );

			if ( tw->trace.fraction < 0 ) {
				tw->trace.fraction = 0;
			}

			VectorCopy( planes->plane,  tw->trace.plane.normal );
			tw->trace.plane.dist = planes->plane[3];
		}
	}
}

/*
====================
CM_CheckFacetPlane
====================
*/
int CM_CheckFacetPlane(float *plane, vec3_t start, vec3_t end, float *enterFrac, float *leaveFrac, int *hit) {
	float d1, d2, f;

	*hit = qfalse;

	d1 = DotProduct( start, plane ) - plane[3];
	d2 = DotProduct( end, plane ) - plane[3];

	// if completely in front of face, no intersection with the entire facet
	if (d1 > 0 && ( d2 >= SURFACE_CLIP_EPSILON || d2 >= d1 )  ) {
		return qfalse;
	}

	// if it doesn't cross the plane, the plane isn't relevent
	if (d1 <= 0 && d2 <= 0 ) {
		return qtrue;
	}

	// crosses face
	if (d1 > d2) {	// enter
		f = (d1-SURFACE_CLIP_EPSILON) / (d1-d2);
		if ( f < 0 ) {
			f = 0;
		}
		//always favor previous plane hits and thus also the surface plane hit
		if (f > *enterFrac) {
			*enterFrac = f;
			*hit = qtrue;
		}
	} else {	// leave
		f = (d1+SURFACE_CLIP_EPSILON) / (d1-d2);
		if ( f > 1 ) {
			f = 1;
		}
		if (f < *leaveFrac) {
			*leaveFrac = f;
		}
	}
	return qtrue;
}

/*
====================
CM_TraceThroughPatchCollide
====================
*/
void CM_TraceThroughPatchCollide( traceWork_t *tw, const struct patchCollide_s *pc )
{
	int i, j, hit, hitnum;
	float offset, enterFrac, leaveFrac, t;
	patchPlane_t *planes;
	facet_t	*facet;
	float plane[4] = { 0.0f }, bestplane[4] = { 0.0f };
	vec3_t startp, endp;
#ifndef BSPC
	static cvar_t *cv;
#endif //BSPC

	if (tw->isPoint) {
		CM_TracePointThroughPatchCollide( tw, pc );
		return;
	}
#ifndef ADDBEVELS
	CM_TracePointThroughPatchCollide( tw, pc );
	return;
#endif
	//
	facet = pc->facets;
	for ( i = 0 ; i < pc->numFacets ; i++, facet++ ) {
		enterFrac = -1.0;
		leaveFrac = 1.0;
		hitnum = -1;
		//
		planes = &pc->planes[ facet->surfacePlane ];
		VectorCopy(planes->plane, plane);
		plane[3] = planes->plane[3];
		if ( tw->sphere.use ) {
			// adjust the plane distance apropriately for radius
			plane[3] += tw->sphere.radius;

			// find the closest point on the capsule to the plane
			t = DotProduct( plane, tw->sphere.offset );
			if ( t > 0.0f )
			{
				VectorSubtract( tw->start, tw->sphere.offset, startp );
				VectorSubtract( tw->end, tw->sphere.offset, endp );
			}
			else
			{
				VectorAdd( tw->start, tw->sphere.offset, startp );
				VectorAdd( tw->end, tw->sphere.offset, endp );
			}
		}
		else {
			offset = DotProduct( tw->offsets[ planes->signbits ], plane);
			plane[3] -= offset;
			VectorCopy( tw->start, startp );
			VectorCopy( tw->end, endp );
		}
		if (!CM_CheckFacetPlane(plane, startp, endp, &enterFrac, &leaveFrac, &hit)) {
			continue;
		}
		if (hit) {
			VectorCopy4(plane, bestplane);
		}
		for ( j = 0 ; j < facet->numBorders ; j++ ) {
			planes = &pc->planes[ facet->borderPlanes[j] ];
			if (facet->borderInward[j]) {
				VectorNegate(planes->plane, plane);
				plane[3] = -planes->plane[3];
			}
			else {
				VectorCopy(planes->plane, plane);
				plane[3] = planes->plane[3];
			}
			if ( tw->sphere.use ) {
				// adjust the plane distance apropriately for radius
				plane[3] += tw->sphere.radius;

				// find the closest point on the capsule to the plane
				t = DotProduct( plane, tw->sphere.offset );
				if ( t > 0.0f )
				{
					VectorSubtract( tw->start, tw->sphere.offset, startp );
					VectorSubtract( tw->end, tw->sphere.offset, endp );
				}
				else
				{
					VectorAdd( tw->start, tw->sphere.offset, startp );
					VectorAdd( tw->end, tw->sphere.offset, endp );
				}
			}
			else {
				// NOTE: this works even though the plane might be flipped because the bbox is centered
				offset = DotProduct( tw->offsets[ planes->signbits ], plane);
				plane[3] += fabs(offset);
				VectorCopy( tw->start, startp );
				VectorCopy( tw->end, endp );
			}
			if (!CM_CheckFacetPlane(plane, startp, endp, &enterFrac, &leaveFrac, &hit)) {
				break;
			}
			if (hit) {
				hitnum = j;
				VectorCopy4(plane, bestplane);
			}
		}
		if (j < facet->numBorders) continue;
		//never clip against the back side
		if (hitnum == facet->numBorders - 1) continue;
		if (enterFrac < leaveFrac && enterFrac >= 0) {
			if (enterFrac < tw->trace.fraction) {
				if (enterFrac < 0) {
					enterFrac = 0;
				}
#ifndef BSPC
				if (!cv) {
					cv = Cvar_Get( "r_debugSurfaceUpdate", "1", 0 );
				}
				if (cv && cv->integer) {
					debugPatchCollide = pc;
					debugFacet = facet;
				}
#endif // BSPC

				tw->trace.fraction = enterFrac;
				VectorCopy( bestplane, tw->trace.plane.normal );
				tw->trace.plane.dist = bestplane[3];
			}
		}
	}
}

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

POSITION TEST

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

#define	BOX_FRONT	0
#define	BOX_BACK	1
#define	BOX_CROSS	2

/*
====================
CM_PositionTestInPatchCollide

Modifies tr->tr if any of the facets effect the trace
====================
*/
qboolean CM_PositionTestInPatchCollide( traceWork_t *tw, const struct patchCollide_s *pc ) {
	int			cross[MAX_PATCH_PLANES];
	const patchPlane_t	*planes;
	const facet_t	*facet;
	int			i, j, k;
	float		offset;
	float		d;

//return qfalse;

#ifndef CULL_BBOX
	for ( i = 0 ; i < 3 ; i++ ) {
		if ( tw->bounds[0][i] > pc->bounds[1][i]
			|| tw->bounds[1][i] < pc->bounds[0][i] ) {
			return qfalse;
		}
	}
#endif

	// determine if the box is in front, behind, or crossing each plane
	planes = pc->planes;
	for ( i = 0 ; i < pc->numPlanes ; i++, planes++ ) {
		d = DotProduct( tw->start, planes->plane ) - planes->plane[3];
		offset = fabs( DotProduct( tw->offsets[ planes->signbits ], planes->plane ) );
		if ( d < -offset ) {
			cross[i] = BOX_FRONT;
		} else if ( d > offset ) {
			cross[i] = BOX_BACK;
		} else {
			cross[i] = BOX_CROSS;
		}
	}


	// see if any of the surface planes are intersected
	facet = pc->facets;
	for ( i = 0 ; i < pc->numFacets ; i++, facet++ ) {
		// the facet plane must be in a cross state
		if ( cross[facet->surfacePlane] != BOX_CROSS ) {
			continue;
		}
		// all of the boundaries must be either cross or back
		for ( j = 0 ; j < facet->numBorders ; j++ ) {
			k = facet->borderPlanes[j];
			if ( cross[ k ] == BOX_CROSS ) {
				continue;
			}
			if ( cross[k] ^ facet->borderInward[j] ) {
				break;
			}
		}
		// if we passed all borders, we are definately in this facet
		if ( j == facet->numBorders ) {
			return qtrue;
		}
	}

	return qfalse;
}

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

DEBUGGING

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


/*
==================
CM_DrawDebugSurface

Called from the renderer
==================
*/
#ifndef BSPC
void BotDrawDebugPolygons(void (*drawPoly)(int color, int numPoints, float *points), int value);
#endif

void CM_DrawDebugSurface( void (*drawPoly)(int color, int numPoints, float *points) ) {

}