openmohaa/code/qcommon/cm_terrain.c

/*
===========================================================================
Copyright (C) 2008 Leszek Godlewski

This file is part of OpenMoHAA source code.

OpenMoHAA source code 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.

OpenMoHAA source code 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 OpenMoHAA source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

// cm_terain.c : LOD Terrain support
// so many headaches

#include "cm_local.h"
#include "cm_terrain.h"

typedef struct varnodeIndex_s {
	short unsigned int iTreeAndMask;
	short unsigned int iNode;
} varnodeIndex_t;

typedef struct worknode_s {
	int i0;
	int j0;
	int i1;
	int j1;
	int i2;
	int j2;
} worknode_t;

typedef struct pointtrace_s {
	traceWork_t *tw;
	terrainCollide_t *tc;
	vec3_t vStart;
	vec3_t vEnd;
	int i;
	int j;
	float fSurfaceClipEpsilon;
} pointtrace_t;

varnodeIndex_t g_vni[ 2 ][ 8 ][ 8 ][ 2 ];
static pointtrace_t g_trace;

static int modeTable[] =
{
	2,
	2,
	5,
	6,
	4,
	3,
	0,
	0
};

/*
=================
CM_SignbitsForNormal
=================
Copied over from cm_patch.c
*/
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_CalculateTerrainIndices
====================
*/
void CM_CalculateTerrainIndices( worknode_t *worknode, int iDiagonal, int iTree )
{
	int i;
	int i2;
	int j2;
	varnodeIndex_t *vni;

	for( i = 0; i <= 30; i++ )
	{
		i2 = worknode[ i + 1 ].i0 + worknode[ i + 1 ].i1;
		j2 = worknode[ i + 1 ].j0 + worknode[ i + 1 ].j1;
		worknode[ i * 2 + 2 ].i0 = worknode[ i + 1 ].i1;
		worknode[ i * 2 + 2 ].j0 = worknode[ i + 1 ].j1;
		worknode[ i * 2 + 2 ].i1 = worknode[ i + 1 ].i2;
		worknode[ i * 2 + 2 ].j1 = worknode[ i + 1 ].j2;
		worknode[ i * 2 + 2 ].i2 = i2 >> 1;
		worknode[ i * 2 + 2 ].j2 = j2 >> 1;
		worknode[ i * 2 + 2 + 1 ].i0 = worknode[ i + 1 ].i2;
		worknode[ i * 2 + 2 + 1 ].j0 = worknode[ i + 1 ].j2;
		worknode[ i * 2 + 2 + 1 ].i1 = worknode[ i + 1 ].i0;
		worknode[ i * 2 + 2 + 1 ].j1 = worknode[ i + 1 ].j0;
		worknode[ i * 2 + 2 + 1 ].i2 = i2 >> 1;
		worknode[ i * 2 + 2 + 1 ].j2 = j2 >> 1;
	}

	for( i = 32; i < 64; i++ )
	{
		i2 = ( worknode[ i ].i0 + worknode[ i ].i1 ) >> 1;
		j2 = ( worknode[ i ].j0 + worknode[ i ].j1 ) >> 1;

		if( worknode[ i ].i0 == worknode[ i ].i1 )
		{
			if( worknode[ i ].j0 <= worknode[ i ].j1 )
			{
				vni = &g_vni[ iDiagonal ][ i2 ][ j2 ][ 1 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x2000;

				vni = &g_vni[ iDiagonal ][ i2 ][ j2 - 1 ][ 0 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x1000;
			}
			else
			{
				vni = &g_vni[ iDiagonal ][ i2 - 1 ][ j2 ][ 1 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x1000;

				vni = &g_vni[ iDiagonal ][ i2 - 1 ][ j2 - 1 ][ 0 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x2000;
			}
		}
		else
		{
			if( worknode[ i ].i0 <= worknode[ i ].i1 )
			{
				vni = &g_vni[ iDiagonal ][ i2 ][ j2 - 1 ][ 0 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x2000;

				vni = &g_vni[ iDiagonal ][ i2 - 1 ][ j2 - 1 ][ 0 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x1000;
			}
			else
			{
				vni = &g_vni[ iDiagonal ][ i2 ][ j2 ][ 1 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x1000;

				vni = &g_vni[ iDiagonal ][ i2 - 1 ][ j2 ][ 1 ];
				vni->iNode = i - 1;
				vni->iTreeAndMask = iTree | 0x2000;
			}
		}

	}
}

/*
====================
CM_PrepareGenerateTerrainCollide
====================
*/
void CM_PrepareGenerateTerrainCollide( void )
{
	worknode_t		worknode[ 64 ];

	memset( &g_vni, 0, sizeof( g_vni ) );

	worknode[ 1 ].i0 = 8;
	worknode[ 1 ].j0 = 8;
	worknode[ 1 ].i1 = 0;
	worknode[ 1 ].j1 = 0;
	worknode[ 1 ].i2 = 0;
	worknode[ 1 ].j2 = 8;

	CM_CalculateTerrainIndices( worknode, 0, 0 );

	worknode[ 1 ].i0 = 0;
	worknode[ 1 ].j0 = 0;
	worknode[ 1 ].i1 = 8;
	worknode[ 1 ].j1 = 8;
	worknode[ 1 ].i2 = 8;
	worknode[ 1 ].j2 = 0;

	CM_CalculateTerrainIndices( worknode, 0, 1 );

	worknode[ 1 ].i0 = 8;
	worknode[ 1 ].j0 = 0;
	worknode[ 1 ].i1 = 0;
	worknode[ 1 ].j1 = 8;
	worknode[ 1 ].i2 = 8;
	worknode[ 1 ].j2 = 8;

	CM_CalculateTerrainIndices( worknode, 1, 0 );

	worknode[ 1 ].i0 = 0;
	worknode[ 1 ].j0 = 8;
	worknode[ 1 ].i1 = 8;
	worknode[ 1 ].j1 = 0;
	worknode[ 1 ].i2 = 0;
	worknode[ 1 ].j2 = 0;

	CM_CalculateTerrainIndices( worknode, 1, 1 );
}

void CM_PickTerrainSquareMode( terrainCollideSquare_t *square, vec3_t vTest, int i, int j, cTerraPatch_t *patch ) {
	int flags0, flags1;
	varnodeIndex_t *vni;

	vni = &g_vni[ ( patch->flags & 0x80 ) ? 1 : 0 ][ i ][ j ][ 0 ];

	flags0 = ( ( unsigned short )( patch->varTree[ vni->iTreeAndMask & 1 ][ vni->iNode ].flags & 0xFFFE & vni->iTreeAndMask ) != 0 );
	flags1 = ( ( unsigned short )( patch->varTree[ vni[ 1 ].iTreeAndMask & 1 ][ vni[ 1 ].iNode ].flags & 0xFFFE & vni[ 1 ].iTreeAndMask ) != 0 );

	square->eMode = modeTable[ ( j + i ) & 1 | 2 * flags0 | 4 * flags1 ];

	if( square->eMode == 2 )
	{
		if( DotProduct( vTest, square->plane[ 0 ] ) < square->plane[ 0 ][ 3 ] ) {
			square->eMode = 1;
		}
	}
	else if( square->eMode == 5 || square->eMode == 6 )
	{
		VectorCopy( square->plane[ 1 ], square->plane[ 0 ] );
	}
}

/*
====================
CM_GenerateTerPatchCollide
====================
*/
void CM_GenerateTerrainCollide( cTerraPatch_t *patch, terrainCollide_t *tc ) {
	int i;
	int j;
	int x0, y0, z0;
	float fMaxHeight;
	float heightmap[ 9 ][ 9 ];
	terrainCollideSquare_t *square;
	vec3_t v1;
	vec3_t v2;
	vec3_t v3;
	vec3_t v4;
	
	x0 = ( patch->x << 6 );
	y0 = ( patch->y << 6 );
	z0 = ( patch->iBaseHeight );

	fMaxHeight = z0;

	for( j = 0; j < 9; j++ )
	{
		for( i = 0; i < 9; i++ )
		{
			heightmap[ i ][ j ] = ( float )( z0 + 2 * patch->heightmap[ j * 9 + i ] );
		}
	}

	for( j = 0; j < 8; j++ )
	{
		for( i = 0; i < 8; i++ )
		{
			v1[ 0 ] = ( ( i << 6 ) + x0 );
			v1[ 1 ] = ( ( j << 6 ) + y0 );
			v1[ 2 ] = heightmap[ i ][ j ];

			v2[ 0 ] = ( ( i << 6 ) + x0 ) + 64;
			v2[ 1 ] = ( ( j << 6 ) + y0 );
			v2[ 2 ] = heightmap[ i + 1 ][ j ];

			v3[ 0 ] = ( ( i << 6 ) + x0 ) + 64;
			v3[ 1 ] = ( ( j << 6 ) + y0 ) + 64;
			v3[ 2 ] = heightmap[ i + 1 ][ j + 1 ];

			v4[ 0 ] = ( ( i << 6 ) + x0 );
			v4[ 1 ] = ( ( j << 6 ) + y0 ) + 64;
			v4[ 2 ] = heightmap[ i ][ j + 1 ];

			if( fMaxHeight < v1[ 2 ] ) {
				fMaxHeight = v1[ 2 ];
			}

			if( fMaxHeight < v2[ 2 ] ) {
				fMaxHeight = v2[ 2 ];
			}

			if( fMaxHeight < v3[ 2 ] ) {
				fMaxHeight = v3[ 2 ];
			}

			if( fMaxHeight < v4[ 2 ] ) {
				fMaxHeight = v4[ 2 ];
			}

			square = &tc->squares[ i ][ j ];

			if( ( i + j ) & 1 )
			{
				if( patch->flags & 0x40 )
				{
					CM_PlaneFromPoints( square->plane[ 0 ], v4, v2, v3 );
					CM_PlaneFromPoints( square->plane[ 1 ], v2, v4, v1 );
				}
				else
				{
					CM_PlaneFromPoints( square->plane[ 0 ], v2, v4, v3 );
					CM_PlaneFromPoints( square->plane[ 1 ], v4, v2, v1 );
				}
				CM_PickTerrainSquareMode( square, v1, i, j, patch );
			}
			else
			{
				if( patch->flags & 0x40 )
				{
					CM_PlaneFromPoints( square->plane[ 0 ], v1, v3, v4 );
					CM_PlaneFromPoints( square->plane[ 1 ], v3, v1, v2 );
				}
				else
				{
					CM_PlaneFromPoints( square->plane[ 0 ], v3, v1, v4 );
					CM_PlaneFromPoints( square->plane[ 1 ], v1, v3, v2 );
				}
				CM_PickTerrainSquareMode( square, v2, i, j, patch );
			}
		}
	}

	tc->vBounds[ 0 ][ 0 ] = x0;
	tc->vBounds[ 0 ][ 1 ] = y0;
	tc->vBounds[ 0 ][ 2 ] = z0;
	tc->vBounds[ 1 ][ 0 ] = ( x0 + 512 );
	tc->vBounds[ 1 ][ 1 ] = ( y0 + 512 );
	tc->vBounds[ 1 ][ 2 ] = fMaxHeight;
}

/*
====================
CM_CheckTerrainPlane
====================
*/
float CM_CheckTerrainPlane( vec4_t plane )
{
	float	d1, d2;
	float	f;

	d1 = DotProduct( g_trace.vStart, plane ) - plane[ 3 ];
	d2 = DotProduct( g_trace.vEnd, plane ) - plane[ 3 ];

	// if completely in front of face, no intersection with the entire brush
	if( d1 > 0 && ( d2 >= SURFACE_CLIP_EPSILON || d2 >= d1 ) ) {
		return 1;
	}

	if( d1 <= 0 && d2 <= 0 )
	{
		if( d1 >= -32 ) {
			return 0;
		}

		if( d2 >= -32 ) {
			return 0;
		}
		return 1;
	}

	if( d1 <= d2 ) {
		return 1;
	}

	f = ( d1 - SURFACE_CLIP_EPSILON ) / ( d1 - d2 );
	if( f < 0 ) {
		f = 0;
	}
	return f;
}

/*
====================
CM_CheckTerrainTriSpherePoint
====================
*/
float CM_CheckTerrainTriSpherePoint( vec3_t v )
{
	vec3_t	vDelta, vDir;
	float	fLenSq;
	float	fRadSq;
	float	fA, fB;
	float	fDiscr;
	float	fFrac;
	float	fSq;
	float	f;

	VectorSubtract( g_trace.vStart, v, vDir );

	fRadSq = sphere.radius * sphere.radius;
	fLenSq = VectorLengthSquared( vDir );

	if( fLenSq <= fRadSq ) {
		g_trace.tw->trace.startsolid = qtrue;
		g_trace.tw->trace.allsolid = qtrue;
		return 0;
	}

	VectorSubtract( g_trace.vEnd, g_trace.vStart, vDelta );

	fA = VectorLengthSquared( vDelta );
	fB = DotProduct( vDelta, vDir );
	fDiscr = fB * fB - ( fLenSq - fRadSq ) * fA;

	if( fDiscr <= 0.0f ) {
		return g_trace.tw->trace.fraction;
	}

	fSq = sqrt( fDiscr );

	if( fA > 0 )
	{
		fFrac = ( -fB - fSq ) / fA - g_trace.fSurfaceClipEpsilon;

		if( fFrac >= 0.0f && fFrac <= g_trace.tw->trace.fraction ) {
			return fFrac;
		}


		fFrac = -fB + fSq;
	}
	else
	{
		fFrac = ( -fB + fSq ) / fA - g_trace.fSurfaceClipEpsilon;

		if( fFrac >= 0.0f && fFrac <= g_trace.tw->trace.fraction ) {
			return fFrac;
		}

		fFrac = -fB - fSq;
	}

	f = fFrac / fA - g_trace.fSurfaceClipEpsilon;
	if( f < 0 || f > g_trace.tw->trace.fraction ) {
		f = g_trace.tw->trace.fraction;
	}

	return f;
}

/*
====================
CM_CheckTerrainTriSphereCorner
====================
*/
float CM_CheckTerrainTriSphereCorner( vec4_t plane, float x0, float y0, int i, int j )
{
	vec3_t	v;

	v[ 0 ] = ( ( i << 6 ) + x0 );
	v[ 1 ] = ( ( j << 6 ) + y0 );
	v[ 2 ] = ( plane[ 3 ] - ( v[ 1 ] * plane[ 1 ] + v[ 0 ] * plane[ 0 ] ) ) / plane[ 2 ];

	return CM_CheckTerrainTriSpherePoint( v );
}

/*
====================
CM_CheckTerrainTriSphereEdge
====================
*/
float CM_CheckTerrainTriSphereEdge( float *plane, float x0, float y0, int i0, int j0, int i1, int j1 )
{
	vec3_t	v0, v1;
	float	fScale;
	float	fRadSq;
	float	S, T;
	vec3_t	vDeltaStart;
	vec3_t	vDirEdge;
	vec3_t	vDirTrace;
	float	fSFromT_Const;
	float	fSFromT_Scale;
	vec3_t	vRFromT_Const;
	vec3_t	vRFromT_Scale;

	// junk variable(s) as usual
	float	fLengthSq, fDot;
	float	fFrac, fFracClip;

	fScale = 1.0 / plane[ 2 ];

	v0[ 0 ] = ( i0 << 6 ) + x0;
	v0[ 1 ] = ( j0 << 6 ) + y0;
	v0[ 2 ] = ( plane[ 3 ] - ( v0[ 0 ] * plane[ 0 ] + v0[ 1 ] * plane[ 1 ] ) ) * fScale;

	v1[ 0 ] = ( i1 << 6 ) + x0;
	v1[ 1 ] = ( j1 << 6 ) + y0;
	v1[ 2 ] = ( plane[ 3 ] - ( v1[ 0 ] * plane[ 0 ] + v1[ 1 ] * plane[ 1 ] ) ) * fScale;

	VectorSubtract( g_trace.vStart, v0, vDirTrace );
	VectorSubtract( v1, v0, vDirEdge );
	VectorSubtract( g_trace.vEnd, g_trace.vStart, vDeltaStart );

	fScale = 1.0 / VectorLengthSquared( vDirEdge );
	S = DotProduct( vDirTrace, vDirEdge ) * fScale;
	T = DotProduct( vDeltaStart, vDirEdge ) * fScale;

	VectorMA( vDirTrace, -S, vDirEdge, vRFromT_Const );
	VectorMA( vDeltaStart, -T, vDirEdge, vRFromT_Scale );

	fRadSq = sphere.radius * sphere.radius;
	fLengthSq = VectorLengthSquared( vRFromT_Const );

	if( fLengthSq <= fRadSq )
	{
		if( S < 0 || S > 1 ) {
			return CM_CheckTerrainTriSpherePoint( v0 );
		}

		g_trace.tw->trace.startsolid = qtrue;
		g_trace.tw->trace.allsolid = qtrue;
		return 1;
	}

	fDot = DotProduct( vRFromT_Scale, vRFromT_Const );
	fSFromT_Scale = VectorLengthSquared( vRFromT_Scale );
	fSFromT_Const = fDot * fDot - ( fLengthSq - fRadSq ) * fSFromT_Scale;

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

	if( fSFromT_Scale > 0 ) {
		fFrac = ( -fDot - sqrt( fSFromT_Const ) ) / fSFromT_Scale;
	} else {
		fFrac = ( -fDot + sqrt( fSFromT_Const ) ) / fSFromT_Scale;
	}

	fFracClip = fFrac - g_trace.fSurfaceClipEpsilon;
	if( fFrac <= 0 || fFracClip >= g_trace.tw->trace.fraction ) {
		return g_trace.tw->trace.fraction;
	}

	fFrac = fFrac * T + S;

	if( fFrac < 0 ) {
		return CM_CheckTerrainTriSpherePoint( v0 );
	}

	if( fFrac > 1 ) {
		return CM_CheckTerrainTriSpherePoint( v1 );
	}

	if( fFracClip < 0 ) {
		fFracClip = 0;
	}
	return fFracClip;
}

/*
====================
CM_CheckTerrainTriSphere
====================
*/
float CM_CheckTerrainTriSphere( float x0, float y0, int iPlane )
{
	float	*plane;
	float	fMaxFraction;
	float	d1, d2;
	float	fSpherePlane;
	int		eMode;
	qboolean	bFitsX, bFitsY;
	qboolean	bFitsDiag;
	int		iX[ 3 ];
	int		iY[ 3 ];

	plane = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ iPlane ];
	d1 = DotProduct( g_trace.vStart, plane ) - plane[ 3 ];
	d2 = DotProduct( g_trace.vEnd, plane ) - plane[ 3 ];

	if( d1 > sphere.radius )
	{
		if( d2 >= sphere.radius + SURFACE_CLIP_EPSILON ) {
			return g_trace.tw->trace.fraction;
		}

		if( d2 >= d1 ) {
			return g_trace.tw->trace.fraction;	
		}
	}

	if( d1 <= -sphere.radius && d2 <= -sphere.radius ) {
		return g_trace.tw->trace.fraction;
	}

	if( d1 <= d2 ) {
		return g_trace.tw->trace.fraction;
	}

	fMaxFraction = SURFACE_CLIP_EPSILON / ( d1 - d2 );
	g_trace.fSurfaceClipEpsilon = fMaxFraction;
	fSpherePlane = ( d1 - sphere.radius ) / ( d1 - d2 ) - fMaxFraction;

	if( fSpherePlane < 0 ) {
		fSpherePlane = 0;
	}

	if( fSpherePlane >= g_trace.tw->trace.fraction ) {
		return g_trace.tw->trace.fraction;
	}

	d1 = ( g_trace.vEnd[ 0 ] - g_trace.vStart[ 0 ] ) * fSpherePlane + g_trace.vEnd[ 0 ] - sphere.radius * plane[ 0 ] - x0;
	d2 = ( g_trace.vEnd[ 1 ] - g_trace.vStart[ 1 ] ) * fSpherePlane + g_trace.vEnd[ 1 ] - sphere.radius * plane[ 1 ] - y0;

	eMode = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].eMode;

	if( eMode == 1 || eMode == 2 )
	{
		if( ( g_trace.i + g_trace.j ) & 1 ) {
			eMode = iPlane ? 6 : 3;
		} else {
			eMode = iPlane ? 5 : 4;
		}
	}

	switch( eMode )
	{
	case 3:
		if( d1 > 64 ) {
			bFitsX = qfalse;
		} else {
			bFitsX = qtrue;
		}
		if( d2 > 64 ) {
			bFitsY = qfalse;
		} else {
			bFitsY = qtrue;
		}

		if( d1 < 64 - d2 ) {
			bFitsDiag = qfalse;
		} else {
			bFitsDiag = qtrue;
		}
		iX[ 0 ] = 1;
		iX[ 1 ] = 1;
		iX[ 2 ] = 1;
		iY[ 0 ] = 0;
		iY[ 1 ] = 1;
		iY[ 2 ] = 0;
		break;
	case 4:
		if( d1 < 0 ) {
			bFitsX = qfalse;
		} else {
			bFitsX = qtrue;
		}
		if( d2 > 64 ) {
			bFitsY = qfalse;
		} else {
			bFitsY = qtrue;
		}

		if( d1 > d2 ) {
			bFitsDiag = qfalse;
		} else {
			bFitsDiag = qtrue;
		}
		iX[ 0 ] = 0;
		iX[ 1 ] = 1;
		iX[ 2 ] = 1;
		iY[ 0 ] = 1;
		iY[ 1 ] = 0;
		iY[ 2 ] = 0;
		break;
	case 5:
		if( d1 > 64 ) {
			bFitsX = qfalse;
		} else {
			bFitsX = qtrue;
		}
		if( d2 < 0 ) {
			bFitsY = qfalse;
		} else {
			bFitsY = qtrue;
		}

		if( d1 < d2 ) {
			bFitsDiag = qfalse;
		} else {
			bFitsDiag = qtrue;
		}
		iX[ 0 ] = 1;
		iX[ 1 ] = 0;
		iX[ 2 ] = 0;
		iY[ 0 ] = 0;
		iY[ 1 ] = 1;
		iY[ 2 ] = 1;
		break;
	case 6:
		if( d1 < 0 ) {
			bFitsX = qfalse;
		} else {
			bFitsX = qtrue;
		}
		if( d2 < 0 ) {
			bFitsY = qfalse;
		} else {
			bFitsY = qtrue;
		}

		if( d1 > 64 - d2 ) {
			bFitsDiag = qfalse;
		} else {
			bFitsDiag = qtrue;
		}
		iX[ 0 ] = 0;
		iX[ 1 ] = 0;
		iX[ 2 ] = 0;
		iY[ 0 ] = 1;
		iY[ 1 ] = 0;
		iY[ 2 ] = 1;
		break;
	default:
		return 0;
	}

	if( bFitsX )
	{
		if( bFitsY )
		{
			if( bFitsDiag ) {
				return fSpherePlane;
			} else {
				return CM_CheckTerrainTriSphereEdge( plane, x0, y0, iY[ 0 ], iX[ 1 ], iY[ 1 ], iY[ 2 ] );
			}
		} else if( bFitsDiag ) {
			return CM_CheckTerrainTriSphereEdge( plane, x0, y0, iX[ 0 ], iX[ 2 ], iY[ 0 ], iX[ 1 ] );
		} else {
			return CM_CheckTerrainTriSphereCorner( plane, x0, y0, iY[ 0 ], iX[ 1 ] );
		}
	}
	else if( bFitsY )
	{
		if( bFitsDiag ) {
			return CM_CheckTerrainTriSphereEdge( plane, x0, y0, iX[ 0 ], iX[ 2 ], iY[ 1 ], iY[ 2 ] );
		} else {
			return CM_CheckTerrainTriSphereCorner( plane, x0, y0, iY[ 1 ], iY[ 2 ] );
		}
	}
	else
	{
		if( bFitsDiag ) {
			return CM_CheckTerrainTriSphereCorner( plane, x0, y0, iX[ 0 ], iX[ 2 ] );
		} else {
			return g_trace.tw->trace.fraction;
		}
	}
}

/*
====================
CM_ValidateTerrainCollidePointSquare
====================
*/
qboolean CM_ValidateTerrainCollidePointSquare( float frac )
{
	float f;

	f = g_trace.vStart[ 0 ] + frac * ( g_trace.vEnd[ 0 ] - g_trace.vStart[ 0 ] )
		- ( ( g_trace.i << 6 ) + g_trace.tc->vBounds[ 0 ][ 0 ] );

	if( f >= 0 && f <= 64 )
	{
		f = g_trace.vStart[ 1 ] + frac * ( g_trace.vEnd[ 1 ] - g_trace.vStart[ 1 ] )
			- ( ( g_trace.j << 6 ) + g_trace.tc->vBounds[ 0 ][ 1 ] );

		if( f >= 0 && f <= 64 ) {
			return qtrue;
		}
	}

	return qfalse;
}

/*
====================
CM_ValidateTerrainCollidePointTri
====================
*/
qboolean CM_ValidateTerrainCollidePointTri( int eMode, float frac )
{
	float	x0, y0;
	float	x, y;
	float	dx, dy;

	x0 = ( g_trace.i << 6 ) + g_trace.tc->vBounds[ 0 ][ 0 ];
	dx = g_trace.vStart[ 0 ] + ( g_trace.vEnd[ 0 ] - g_trace.vStart[ 0 ] ) * frac;
	x = x0 + 64;

	if( x0 > dx ) {
		return qfalse;
	}

	if( x < dx ) {
		return qfalse;
	}

	y0 = ( g_trace.j << 6 ) + g_trace.tc->vBounds[ 0 ][ 1 ];
	dy = g_trace.vStart[ 1 ] + ( g_trace.vEnd[ 1 ] - g_trace.vStart[ 1 ] ) * frac;
	y = y0 + 64;

	if( y0 > dy ) {
		return qfalse;
	}

	if( y < dy ) {
		return qfalse;
	}

	switch( eMode )
	{
	case 3:
		return ( dx - x0 ) >= ( 64 - ( dy - y0 ) );
	case 4:
		return ( dx - x0 ) <= ( dy - y0 );
	case 5:
		return ( dx - x0 ) >= ( dy - y0 );
	case 6:
		return ( dx - x0 ) <= ( 64 - ( dy - y0 ) );
	default:
		return qtrue;
	}
}

/*
====================
CM_TestTerrainCollideSquare
====================
*/
qboolean CM_TestTerrainCollideSquare( void )
{
	float	*plane;
	float	frac0;
	float	enterFrac;
	int		eMode;

	eMode = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].eMode;

	if( !eMode ) {
		return qfalse;
	}

	if( eMode >= 0 && eMode <= 2 )
	{
		enterFrac = CM_CheckTerrainPlane( g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 0 ] );

		plane = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 1 ];
		frac0 = CM_CheckTerrainPlane( plane );

		if( eMode == 2 )
		{
			if( enterFrac > frac0 ) {
				enterFrac = frac0;
			}
		}
		else
		{
			if( enterFrac < frac0 ) {
				enterFrac = frac0;
			}
		}

		if( enterFrac < g_trace.tw->trace.fraction && CM_ValidateTerrainCollidePointSquare( enterFrac ) )
		{
			g_trace.tw->trace.fraction = enterFrac;
			VectorCopy( plane, g_trace.tw->trace.plane.normal );
			g_trace.tw->trace.plane.dist = plane[ 3 ];
			return qtrue;
		}
	}
	else
	{
		plane = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 0 ];
		enterFrac = CM_CheckTerrainPlane( plane );

		if( enterFrac < g_trace.tw->trace.fraction
			&& CM_ValidateTerrainCollidePointTri( g_trace.tc->squares[ g_trace.i ][ g_trace.j ].eMode, enterFrac ) )
		{
			g_trace.tw->trace.fraction = enterFrac;
			VectorCopy( plane, g_trace.tw->trace.plane.normal );
			g_trace.tw->trace.plane.dist = plane[ 3 ];
			return qtrue;
		}
	}

	return qfalse;
}

/*
====================
CM_CheckStartInsideTerrain
====================
*/
static qboolean CM_CheckStartInsideTerrain( int i, int j, float fx, float fy )
{
	float	*plane;
	float	fDot;

	if( i < 0 || i > 7 ) {
		return qfalse;
	}
	if( j < 0 || j > 7 ) {
		return qfalse;
	}

	if( !g_trace.tc->squares[ i ][ j ].eMode ) {
		return qfalse;
	}

	if( ( i + j ) & 1 )
	{
		if( fx + fy >= 1 )
		{
			if( g_trace.tc->squares[ i ][ j ].eMode == 6 ) {
				return qfalse;
			}
			plane = g_trace.tc->squares[ i ][ j ].plane[ 0 ];
		}
		else
		{
			if( g_trace.tc->squares[ i ][ j ].eMode == 3 ) {
				return qfalse;
			}
			plane = g_trace.tc->squares[ i ][ j ].plane[ 1 ];
		}
	}
	else
	{
		if( fy >= fx )
		{
			if( g_trace.tc->squares[ i ][ j ].eMode == 5 ) {
				return qfalse;
			}
			plane = g_trace.tc->squares[ i ][ j ].plane[ 0 ];
		}
		else
		{
			if( g_trace.tc->squares[ i ][ j ].eMode == 4 ) {
				return qfalse;
			}
			plane = g_trace.tc->squares[ i ][ j ].plane[ 1 ];
		}
	}

	fDot = DotProduct( g_trace.vStart, plane );
	if( fDot <= plane[ 3 ] && fDot + 32.0f >= plane[ 3 ] ) {
		return qtrue;
	}

	return qfalse;
}

/*
====================
CM_PositionTestPointInTerrainCollide
====================
*/
qboolean CM_PositionTestPointInTerrainCollide( void )
{
	int		i0, j0;
	float	fx, fy;

	fx = ( g_trace.vStart[ 0 ] - g_trace.tc->vBounds[ 0 ][ 0 ] ) * ( SURFACE_CLIP_EPSILON / 8 );
	fy = ( g_trace.vStart[ 1 ] - g_trace.tc->vBounds[ 0 ][ 1 ] ) * ( SURFACE_CLIP_EPSILON / 8 );

	i0 = ( int )floor( fx );
	j0 = ( int )floor( fy );

	return CM_CheckStartInsideTerrain( i0, j0, fx - i0, fy - j0 );
}

/*
====================
CM_TracePointThroughTerrainCollide
====================
*/
void CM_TracePointThroughTerrainCollide( void )
{
	int i0, j0, i1, j1;
	int di, dj;
	int d1, d2;
	//int nTotal;
	float fx, fy;
	float dx, dy, dx2, dy2;

	fx = (g_trace.vStart[0] - g_trace.tc->vBounds[0][0]) * (SURFACE_CLIP_EPSILON / 8);
	fy = (g_trace.vStart[1] - g_trace.tc->vBounds[0][1]) * (SURFACE_CLIP_EPSILON / 8);
	i0 = (int64_t)floor(fx);
	j0 = (int64_t)floor(fy);
	i1 = (int64_t)floor((g_trace.vEnd[0] - g_trace.tc->vBounds[0][0]) * (SURFACE_CLIP_EPSILON / 8));
	j1 = (int64_t)floor((g_trace.vEnd[1] - g_trace.tc->vBounds[0][1]) * (SURFACE_CLIP_EPSILON / 8));

	const float dfx = fx - i0;
	const float dfy = fy - j0;

	if (CM_CheckStartInsideTerrain(i0, j0, dfx, dfy))
	{
		g_trace.tw->trace.startsolid = qtrue;
		g_trace.tw->trace.allsolid = qtrue;
		g_trace.tw->trace.fraction = 0;
		return;
	}

	if (i0 == i1)
	{
		if (i0 < 0 || i0 > 7) {
			return;
		}

		if (j0 == j1)
		{
			if (j0 < 0 || j0 > 7) {
				return;
			}

			g_trace.i = i0;
			g_trace.j = j0;
			CM_TestTerrainCollideSquare();
		}
		else if (j0 >= j1)
		{
			if (j0 > 7)
				j0 = 7;
			if (j1 < 0)
				j1 = 0;

			g_trace.i = i0;
			for (g_trace.j = j0; g_trace.j >= j1; g_trace.j--) {
				if (CM_TestTerrainCollideSquare()) {
					return;
				}
			}
		}
		else
		{
			if (j0 < 0)
				j0 = 0;
			if (j1 > 7)
				j1 = 7;

			g_trace.i = i0;
			for (g_trace.j = j0; g_trace.j <= j1; g_trace.j++) {
				if (CM_TestTerrainCollideSquare()) {
					return;
				}
			}
		}
	}
	else if (j0 == j1)
	{
		if (j0 < 0 || j0 > 7) {
			return;
		}

		if (i0 >= i1)
		{
			if (i0 > 7)
				i0 = 7;
			if (i1 < 0)
				i1 = 0;

			g_trace.j = j0;
			for (g_trace.i = i0; g_trace.i >= i1; g_trace.i--) {
				if (CM_TestTerrainCollideSquare()) {
					break;
				}
			}
		}
		else
		{
			if (i0 < 0)
				i0 = 0;
			if (i1 > 7)
				i1 = 7;

			g_trace.j = j0;
			for (g_trace.i = i0; g_trace.i <= i1; g_trace.i++) {
				if (CM_TestTerrainCollideSquare()) {
					break;
				}
			}
		}
	}
	else
	{
		dx = g_trace.vEnd[0] - g_trace.vStart[0];
		dy = g_trace.vEnd[1] - g_trace.vStart[1];

		// Fix
		//==
		// The original compares if delta float is zero
		// not only it's slower, but it can be problematic if those floats are NaN
		//==
		if (i1 > i0)
		{
			// dx positive
			d1 = 1;
			di = i1 - i0;
			dx2 = (i0 + 1 - fx) * dy;
		}
		else
		{
			d1 = -1;
			di = i0 - i1;
			dx = -dx;
			dx2 = dfx * dy;
		}

		if (j1 > j0)
		{
			// dy positive
			d2 = 1;
			dj = di + j1 - j0 + 1;
			dy2 = (j0 + 1 - fy) * dx;
		}
		else
		{
			d2 = -1;
			dy = -dy;
			dj = di + j0 - j1 + 1;
			dy2 = dfy * dx;
			dx2 = -dx2;
		}

		g_trace.i = i0;
		g_trace.j = j0;

		while (1)
		{
			if (g_trace.i >= 0 && g_trace.i <= 7 && g_trace.j >= 0 && g_trace.j <= 7)
			{
				if (CM_TestTerrainCollideSquare()) {
					return;
				}
			}

			dj--;
			if (!dj) {
				break;
			}

			if (dx2 < dy2)
			{
				dy2 -= dx2;
				dx2 = dy;
				g_trace.i += d1;
			}
			else
			{
				dx2 -= dy2;
				dy2 = dx;
				g_trace.j += d2;
			}
		}
	}
}

/*
====================
CM_TraceCylinderThroughTerrainCollide
====================
*/
void CM_TraceCylinderThroughTerrainCollide( traceWork_t *tw, const terrainCollide_t *tc )
{
	int i0, j0, i1, j1;
	float x0, y0;
	float enterFrac;

	i0 = ( int )( floor( tw->bounds[ 0 ][ 0 ] - tc->vBounds[ 0 ][ 0 ] ) * ( SURFACE_CLIP_EPSILON / 8 ) );
	i1 = ( int )( floor( tw->bounds[ 1 ][ 0 ] - tc->vBounds[ 0 ][ 0 ] ) * ( SURFACE_CLIP_EPSILON / 8 ) );
	j0 = ( int )( floor( tw->bounds[ 0 ][ 1 ] - tc->vBounds[ 0 ][ 1 ] ) * ( SURFACE_CLIP_EPSILON / 8 ) );
	j1 = ( int )( floor( tw->bounds[ 1 ][ 1 ] - tc->vBounds[ 0 ][ 1 ] ) * ( SURFACE_CLIP_EPSILON / 8 ) );

	if( i0 < 0 )
		i0 = 0;
	if( j0 < 0 )
		j0 = 0;
	if( i1 > 7 )
		i1 = 7;
	if( j1 > 7 )
		j1 = 7;

	y0 = ( j0 << 6 ) + tc->vBounds[ 0 ][ 1 ];
	for( g_trace.j = j0; g_trace.j <= j1; g_trace.j++ )
	{
		x0 = ( i0 << 6 ) + tc->vBounds[ 0 ][ 0 ];
		for( g_trace.i = i0; g_trace.i <= i1; g_trace.i++ )
		{
			switch( tc->squares[ g_trace.i ][ g_trace.j ].eMode )
			{
			case 1:
			case 2:
				enterFrac = CM_CheckTerrainTriSphere( x0, y0, 0 );
				if( enterFrac < 0 )
					enterFrac = 0;
				if( enterFrac < g_trace.tw->trace.fraction )
				{
					g_trace.tw->trace.fraction = enterFrac;
					VectorCopy( g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 0 ], g_trace.tw->trace.plane.normal );
					g_trace.tw->trace.plane.dist = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 0 ][ 3 ];
				}
				enterFrac = CM_CheckTerrainTriSphere( x0, y0, 1 );
				if( enterFrac < 0 )
					enterFrac = 0;
				if( enterFrac < g_trace.tw->trace.fraction )
				{
					g_trace.tw->trace.fraction = enterFrac;
					VectorCopy( g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 1 ], g_trace.tw->trace.plane.normal );
					g_trace.tw->trace.plane.dist = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 1 ][ 3 ];
				}
				break;
			case 3:	
			case 4:
				enterFrac = CM_CheckTerrainTriSphere( x0, y0, 0 );
				if( enterFrac < 0 )
					enterFrac = 0;
				if( enterFrac < g_trace.tw->trace.fraction )
				{
					g_trace.tw->trace.fraction = enterFrac;
					VectorCopy( g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 0 ], g_trace.tw->trace.plane.normal );
					g_trace.tw->trace.plane.dist = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 0 ][ 3 ];
				}
				break;
			case 5:
			case 6:
				enterFrac = CM_CheckTerrainTriSphere( x0, y0, 1 );
				if( enterFrac < 0 )
					enterFrac = 0;
				if( enterFrac < g_trace.tw->trace.fraction )
				{
					g_trace.tw->trace.fraction = enterFrac;
					VectorCopy( g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 1 ], g_trace.tw->trace.plane.normal );
					g_trace.tw->trace.plane.dist = g_trace.tc->squares[ g_trace.i ][ g_trace.j ].plane[ 1 ][ 3 ];
				}
				break;
			default:
				break;
			}
			x0 += 64;
		}

		y0 += 64;
	}
}

/*
====================
CM_TraceThroughTerrainCollide
====================
*/
void CM_TraceThroughTerrainCollide( traceWork_t *tw, terrainCollide_t *tc ) {
	int i;

	if( tw->bounds[ 0 ][ 0 ] >= tc->vBounds[ 1 ][ 0 ] ||
		tw->bounds[ 0 ][ 1 ] >= tc->vBounds[ 1 ][ 1 ] ||
		tw->bounds[ 0 ][ 2 ] >= tc->vBounds[ 1 ][ 2 ] ||
		tw->bounds[ 1 ][ 0 ] <= tc->vBounds[ 0 ][ 0 ] ||
		tw->bounds[ 1 ][ 1 ] <= tc->vBounds[ 0 ][ 1 ] ||
		tw->bounds[ 1 ][ 2 ] <= tc->vBounds[ 0 ][ 2 ] )
	{
		return;
	}

	g_trace.tw = tw;
	g_trace.tc = tc;
	VectorCopy( tw->start, g_trace.vStart );
	VectorCopy( tw->end, g_trace.vEnd );

	if( sphere.use && cm_ter_usesphere->integer )
	{
		VectorSubtract( tw->start, sphere.offset, g_trace.vStart );
		VectorSubtract( tw->end, sphere.offset, g_trace.vEnd );
		CM_TraceCylinderThroughTerrainCollide( tw, tc );
	}
	else if( tw->isPoint )
	{
		VectorCopy( tw->start, g_trace.vStart );
		VectorCopy( tw->end, g_trace.vEnd );
		CM_TracePointThroughTerrainCollide();
	}
	else
	{
		if( tc->squares[ 0 ][ 0 ].plane[ 0 ][ 2 ] >= 0 )
		{
			for( i = 0; i < 4; i++ )
			{
				VectorAdd( tw->start, tw->offsets[ i ], g_trace.vStart );
				VectorAdd( tw->end, tw->offsets[ i ], g_trace.vEnd );

				CM_TracePointThroughTerrainCollide();
				if( tw->trace.allsolid ) {
					return;
				}
			}
		}
		else
		{
			for( i = 4; i < 8; i++ )
			{
				VectorAdd( tw->start, tw->offsets[ i ], g_trace.vStart );
				VectorAdd( tw->end, tw->offsets[ i ], g_trace.vEnd );

				CM_TracePointThroughTerrainCollide();
				if( tw->trace.allsolid ) {
					return;
				}
			}
		}
	}
}

/*
====================
CM_PositionTestInTerrainCollide
====================
*/
qboolean CM_PositionTestInTerrainCollide( traceWork_t *tw, terrainCollide_t *tc ) {
	int i;

	if( tw->bounds[ 0 ][ 0 ] >= tc->vBounds[ 1 ][ 0 ] ||
		tw->bounds[ 0 ][ 1 ] >= tc->vBounds[ 1 ][ 1 ] ||
		tw->bounds[ 0 ][ 2 ] >= tc->vBounds[ 1 ][ 2 ] ||
		tw->bounds[ 1 ][ 0 ] <= tc->vBounds[ 0 ][ 0 ] ||
		tw->bounds[ 1 ][ 1 ] <= tc->vBounds[ 0 ][ 1 ] ||
		tw->bounds[ 1 ][ 2 ] <= tc->vBounds[ 0 ][ 2 ] )
	{
		return qfalse;
	}

	g_trace.tw = tw;
	g_trace.tc = tc;
	VectorCopy( tw->start, g_trace.vStart );
	VectorCopy( tw->end, g_trace.vEnd );

	if( sphere.use && cm_ter_usesphere->integer )
	{
		VectorSubtract( tw->start, sphere.offset, g_trace.vStart );
		VectorSubtract( tw->end, sphere.offset, g_trace.vEnd );
		CM_TraceCylinderThroughTerrainCollide( tw, tc );
		return tw->trace.startsolid;
	}
	else if( tw->isPoint )
	{
		VectorCopy( tw->start, g_trace.vStart );
		VectorCopy( tw->end, g_trace.vEnd );
		return CM_PositionTestPointInTerrainCollide();
	}
	else
	{
		if( tc->squares[ 0 ][ 0 ].plane[ 0 ][ 2 ] >= 0 )
		{
			for( i = 0; i < 4; i++ )
			{
				VectorAdd( tw->start, tw->offsets[ i ], g_trace.vStart );
				VectorAdd( tw->end, tw->offsets[ i ], g_trace.vEnd );

				if( CM_PositionTestPointInTerrainCollide() ) {
					return qtrue;
				}
			}
		}
		else
		{
			for( i = 4; i < 8; i++ )
			{
				VectorAdd( tw->start, tw->offsets[ i ], g_trace.vStart );
				VectorAdd( tw->end, tw->offsets[ i ], g_trace.vEnd );

				if( CM_PositionTestPointInTerrainCollide() ) {
					return qtrue;
				}
			}
		}
	}

	return qfalse;
}

/*
====================
CM_SightTracePointThroughTerrainCollide
====================
*/
qboolean CM_SightTracePointThroughTerrainCollide( void )
{
	int		i0, j0;
	int		i1, j1;
	int		di, dj;
	float	fx, fy;
	float	dx, dy, dx2, dy2;
	float	d1, d2;

	fx = ( g_trace.vStart[ 0 ] - g_trace.tc->vBounds[ 0 ][ 0 ] ) * ( SURFACE_CLIP_EPSILON / 8 );
	fy = ( g_trace.vStart[ 1 ] - g_trace.tc->vBounds[ 0 ][ 1 ] ) * ( SURFACE_CLIP_EPSILON / 8 );
	i0 = ( int )floor( fx );
	j0 = ( int )floor( fy );
	i1 = ( int )floor( ( g_trace.vEnd[ 0 ] - g_trace.tc->vBounds[ 0 ][ 0 ] ) * ( SURFACE_CLIP_EPSILON / 8 ) );
	j1 = ( int )floor( ( g_trace.vEnd[ 1 ] - g_trace.tc->vBounds[ 0 ][ 1 ] ) * ( SURFACE_CLIP_EPSILON / 8 ) );

	if( CM_CheckStartInsideTerrain( i0, j0, fx - i0, fy - j0 ) ) {
		return qfalse;
	}

	if( i0 == i1 )
	{
		if( i0 < 0 || i0 > 7 ) {
			return qtrue;
		}

		if( j0 == j1 )
		{
			if( j0 < 0 || j0 > 7 ) {
				return qtrue;
			}

			g_trace.i = i0;
			g_trace.j = j0;
			return !CM_TestTerrainCollideSquare();
		}
		else if( j0 >= j1 )
		{
			if( j0 > 7 )
				j0 = 7;
			if( j1 < 0 )
				j1 = 0;

			g_trace.i = i0;
			for( g_trace.j = j0; g_trace.j >= j1; g_trace.j-- ) {
				if( CM_TestTerrainCollideSquare() ) {
					return qfalse;
				}
			}
		}
		else
		{
			if( j0 < 0 )
				j0 = 0;
			if( j1 > 7 )
				j1 = 7;

			g_trace.i = i0;
			for( g_trace.j = j0; g_trace.j <= j1; g_trace.j++ ) {
				if( CM_TestTerrainCollideSquare() ) {
					return qfalse;
				}
			}
		}
	}
	else if( j0 == j1 )
	{
		if( j0 < 0 || j0 > 7 ) {
			return qtrue;
		}

		if( i0 >= i1 )
		{
			if( i0 > 7 )
				i0 = 7;
			if( i1 < 0 )
				i1 = 0;

			g_trace.j = j0;
			for( g_trace.i = i0; g_trace.i >= i1; g_trace.i-- ) {
				if( CM_TestTerrainCollideSquare() ) {
					return qfalse;
				}
			}
		}
		else
		{
			if( i0 < 0 )
				i0 = 0;
			if( i1 > 7 )
				i1 = 7;

			g_trace.j = j0;
			for( g_trace.i = i0; g_trace.i <= i1; g_trace.i++ ) {
				if( CM_TestTerrainCollideSquare() ) {
					return qfalse;
				}
			}
		}
	}
	else
	{
		dx = g_trace.vEnd[ 0 ] - g_trace.vStart[ 0 ];
		dy = g_trace.vEnd[ 1 ] - g_trace.vStart[ 1 ];

		if( dx > 0 )
		{
			d1 = 1;
			di = i1 - i0;
			dx2 = ( i0 + 1 - fx ) * dy;
		}
		else
		{
			d1 = -1;
			di = i0 - i1;
			dx = -dx;
			dx2 = ( fx - i0 ) * dy;
		}

		if( dy > 0 )
		{
			d2 = 1;
			dj = di + j1 - j0 + 1;
			dy2 = ( j0 + 1 - fy ) * dx;
		}
		else
		{
			d2 = -1;
			dy = -dy;
			dj = di + j0 - j1 + 1;
			dy2 = ( fy - j0 ) * dx;
			dx2 = -dx2;
		}

		g_trace.i = i0;
		g_trace.j = j0;

		while( 1 )
		{
			if( g_trace.i >= 0 && g_trace.i <= 7 && g_trace.j >= 0 && g_trace.j <= 7 )
			{
				if( CM_TestTerrainCollideSquare() ) {
					return qfalse;
				}
			}

			dj--;
			if( !dj ) {
				break;
			}

			if( dx2 < dy2 )
			{
				dy2 -= dx2;
				dx2 = dy;
				g_trace.i += d1;
			}
			else
			{
				dx2 -= dy2;
				dy2 = dx;
				g_trace.j += d2;
			}
		}
	}

	return qtrue;
}

/*
====================
CM_SightTraceThroughTerrainCollide
====================
*/
qboolean CM_SightTraceThroughTerrainCollide( traceWork_t *tw, terrainCollide_t *tc )
{
	int i;

	if( tw->bounds[ 0 ][ 0 ] >= tc->vBounds[ 1 ][ 0 ] ||
		tw->bounds[ 0 ][ 1 ] >= tc->vBounds[ 1 ][ 1 ] ||
		tw->bounds[ 0 ][ 2 ] >= tc->vBounds[ 1 ][ 2 ] ||
		tw->bounds[ 1 ][ 0 ] <= tc->vBounds[ 0 ][ 0 ] ||
		tw->bounds[ 1 ][ 1 ] <= tc->vBounds[ 0 ][ 1 ] ||
		tw->bounds[ 1 ][ 2 ] <= tc->vBounds[ 0 ][ 2 ] )
	{
		return qtrue;
	}

	g_trace.tw = tw;
	g_trace.tc = tc;
	VectorCopy( tw->start, g_trace.vStart );
	VectorCopy( tw->end, g_trace.vEnd );

	if( tw->isPoint )
	{
		VectorCopy( tw->start, g_trace.vStart );
		VectorCopy( tw->end, g_trace.vEnd );
		return CM_SightTracePointThroughTerrainCollide();
	}
	else
	{
		if( tc->squares[ 0 ][ 0 ].plane[ 0 ][ 2 ] >= 0 )
		{
			for( i = 0; i < 4; i++ )
			{
				VectorAdd( tw->start, tw->offsets[ i ], g_trace.vStart );
				VectorAdd( tw->end, tw->offsets[ i ], g_trace.vEnd );

				if( !CM_SightTracePointThroughTerrainCollide() ) {
					return qfalse;
				}
			}
		}
		else
		{
			for( i = 4; i < 8; i++ )
			{
				VectorAdd( tw->start, tw->offsets[ i ], g_trace.vStart );
				VectorAdd( tw->end, tw->offsets[ i ], g_trace.vEnd );

				if( !CM_SightTracePointThroughTerrainCollide() ) {
					return qfalse;
				}
			}
		}
	}

	return qtrue;
}

/*
====================
CM_TerrainSquareType
====================
*/
int CM_TerrainSquareType( int iTerrainPatch, int i, int j )
{
	return cm.terrain[ iTerrainPatch ].tc.squares[ i ][ j ].eMode;
}