path: root/src/qcommon/q_math.c

/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.
Copyright (C) 2000-2006 Tim Angus

This file is part of Tremulous.

Tremulous 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.

Tremulous 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 Tremulous; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
//
// q_math.c -- stateless support routines that are included in each code module

// Some of the vector functions are static inline in q_shared.h. q3asm
// doesn't understand static functions though, so we only want them in
// one file. That's what this is about.
#ifdef Q3_VM
#define __Q3_VM_MATH
#endif

#include "q_shared.h"

vec3_t	vec3_origin = {0,0,0};
vec3_t	axisDefault[3] = { { 1, 0, 0 }, { 0, 1, 0 }, { 0, 0, 1 } };


vec4_t		colorBlack	= {0, 0, 0, 1};
vec4_t		colorRed	= {1, 0, 0, 1};
vec4_t		colorGreen	= {0, 1, 0, 1};
vec4_t		colorBlue	= {0, 0, 1, 1};
vec4_t		colorYellow	= {1, 1, 0, 1};
vec4_t		colorMagenta= {1, 0, 1, 1};
vec4_t		colorCyan	= {0, 1, 1, 1};
vec4_t		colorWhite	= {1, 1, 1, 1};
vec4_t		colorLtGrey	= {0.75, 0.75, 0.75, 1};
vec4_t		colorMdGrey	= {0.5, 0.5, 0.5, 1};
vec4_t		colorDkGrey	= {0.25, 0.25, 0.25, 1};

vec4_t	g_color_table[8] =
	{
	{0.0, 0.0, 0.0, 1.0},
	{1.0, 0.0, 0.0, 1.0},
	{0.0, 1.0, 0.0, 1.0},
	{1.0, 1.0, 0.0, 1.0},
	{0.0, 0.0, 1.0, 1.0},
	{0.0, 1.0, 1.0, 1.0},
	{1.0, 0.0, 1.0, 1.0},
	{1.0, 1.0, 1.0, 1.0},
	};


vec3_t	bytedirs[NUMVERTEXNORMALS] =
{
{-0.525731f, 0.000000f, 0.850651f}, {-0.442863f, 0.238856f, 0.864188f}, 
{-0.295242f, 0.000000f, 0.955423f}, {-0.309017f, 0.500000f, 0.809017f}, 
{-0.162460f, 0.262866f, 0.951056f}, {0.000000f, 0.000000f, 1.000000f}, 
{0.000000f, 0.850651f, 0.525731f}, {-0.147621f, 0.716567f, 0.681718f}, 
{0.147621f, 0.716567f, 0.681718f}, {0.000000f, 0.525731f, 0.850651f}, 
{0.309017f, 0.500000f, 0.809017f}, {0.525731f, 0.000000f, 0.850651f}, 
{0.295242f, 0.000000f, 0.955423f}, {0.442863f, 0.238856f, 0.864188f}, 
{0.162460f, 0.262866f, 0.951056f}, {-0.681718f, 0.147621f, 0.716567f}, 
{-0.809017f, 0.309017f, 0.500000f},{-0.587785f, 0.425325f, 0.688191f}, 
{-0.850651f, 0.525731f, 0.000000f},{-0.864188f, 0.442863f, 0.238856f}, 
{-0.716567f, 0.681718f, 0.147621f},{-0.688191f, 0.587785f, 0.425325f}, 
{-0.500000f, 0.809017f, 0.309017f}, {-0.238856f, 0.864188f, 0.442863f}, 
{-0.425325f, 0.688191f, 0.587785f}, {-0.716567f, 0.681718f, -0.147621f}, 
{-0.500000f, 0.809017f, -0.309017f}, {-0.525731f, 0.850651f, 0.000000f}, 
{0.000000f, 0.850651f, -0.525731f}, {-0.238856f, 0.864188f, -0.442863f}, 
{0.000000f, 0.955423f, -0.295242f}, {-0.262866f, 0.951056f, -0.162460f}, 
{0.000000f, 1.000000f, 0.000000f}, {0.000000f, 0.955423f, 0.295242f}, 
{-0.262866f, 0.951056f, 0.162460f}, {0.238856f, 0.864188f, 0.442863f}, 
{0.262866f, 0.951056f, 0.162460f}, {0.500000f, 0.809017f, 0.309017f}, 
{0.238856f, 0.864188f, -0.442863f},{0.262866f, 0.951056f, -0.162460f}, 
{0.500000f, 0.809017f, -0.309017f},{0.850651f, 0.525731f, 0.000000f}, 
{0.716567f, 0.681718f, 0.147621f}, {0.716567f, 0.681718f, -0.147621f}, 
{0.525731f, 0.850651f, 0.000000f}, {0.425325f, 0.688191f, 0.587785f}, 
{0.864188f, 0.442863f, 0.238856f}, {0.688191f, 0.587785f, 0.425325f}, 
{0.809017f, 0.309017f, 0.500000f}, {0.681718f, 0.147621f, 0.716567f}, 
{0.587785f, 0.425325f, 0.688191f}, {0.955423f, 0.295242f, 0.000000f}, 
{1.000000f, 0.000000f, 0.000000f}, {0.951056f, 0.162460f, 0.262866f}, 
{0.850651f, -0.525731f, 0.000000f},{0.955423f, -0.295242f, 0.000000f}, 
{0.864188f, -0.442863f, 0.238856f}, {0.951056f, -0.162460f, 0.262866f}, 
{0.809017f, -0.309017f, 0.500000f}, {0.681718f, -0.147621f, 0.716567f}, 
{0.850651f, 0.000000f, 0.525731f}, {0.864188f, 0.442863f, -0.238856f}, 
{0.809017f, 0.309017f, -0.500000f}, {0.951056f, 0.162460f, -0.262866f}, 
{0.525731f, 0.000000f, -0.850651f}, {0.681718f, 0.147621f, -0.716567f}, 
{0.681718f, -0.147621f, -0.716567f},{0.850651f, 0.000000f, -0.525731f}, 
{0.809017f, -0.309017f, -0.500000f}, {0.864188f, -0.442863f, -0.238856f}, 
{0.951056f, -0.162460f, -0.262866f}, {0.147621f, 0.716567f, -0.681718f}, 
{0.309017f, 0.500000f, -0.809017f}, {0.425325f, 0.688191f, -0.587785f}, 
{0.442863f, 0.238856f, -0.864188f}, {0.587785f, 0.425325f, -0.688191f}, 
{0.688191f, 0.587785f, -0.425325f}, {-0.147621f, 0.716567f, -0.681718f}, 
{-0.309017f, 0.500000f, -0.809017f}, {0.000000f, 0.525731f, -0.850651f}, 
{-0.525731f, 0.000000f, -0.850651f}, {-0.442863f, 0.238856f, -0.864188f}, 
{-0.295242f, 0.000000f, -0.955423f}, {-0.162460f, 0.262866f, -0.951056f}, 
{0.000000f, 0.000000f, -1.000000f}, {0.295242f, 0.000000f, -0.955423f}, 
{0.162460f, 0.262866f, -0.951056f}, {-0.442863f, -0.238856f, -0.864188f}, 
{-0.309017f, -0.500000f, -0.809017f}, {-0.162460f, -0.262866f, -0.951056f}, 
{0.000000f, -0.850651f, -0.525731f}, {-0.147621f, -0.716567f, -0.681718f}, 
{0.147621f, -0.716567f, -0.681718f}, {0.000000f, -0.525731f, -0.850651f}, 
{0.309017f, -0.500000f, -0.809017f}, {0.442863f, -0.238856f, -0.864188f}, 
{0.162460f, -0.262866f, -0.951056f}, {0.238856f, -0.864188f, -0.442863f}, 
{0.500000f, -0.809017f, -0.309017f}, {0.425325f, -0.688191f, -0.587785f}, 
{0.716567f, -0.681718f, -0.147621f}, {0.688191f, -0.587785f, -0.425325f}, 
{0.587785f, -0.425325f, -0.688191f}, {0.000000f, -0.955423f, -0.295242f}, 
{0.000000f, -1.000000f, 0.000000f}, {0.262866f, -0.951056f, -0.162460f}, 
{0.000000f, -0.850651f, 0.525731f}, {0.000000f, -0.955423f, 0.295242f}, 
{0.238856f, -0.864188f, 0.442863f}, {0.262866f, -0.951056f, 0.162460f}, 
{0.500000f, -0.809017f, 0.309017f}, {0.716567f, -0.681718f, 0.147621f}, 
{0.525731f, -0.850651f, 0.000000f}, {-0.238856f, -0.864188f, -0.442863f}, 
{-0.500000f, -0.809017f, -0.309017f}, {-0.262866f, -0.951056f, -0.162460f}, 
{-0.850651f, -0.525731f, 0.000000f}, {-0.716567f, -0.681718f, -0.147621f}, 
{-0.716567f, -0.681718f, 0.147621f}, {-0.525731f, -0.850651f, 0.000000f}, 
{-0.500000f, -0.809017f, 0.309017f}, {-0.238856f, -0.864188f, 0.442863f}, 
{-0.262866f, -0.951056f, 0.162460f}, {-0.864188f, -0.442863f, 0.238856f}, 
{-0.809017f, -0.309017f, 0.500000f}, {-0.688191f, -0.587785f, 0.425325f}, 
{-0.681718f, -0.147621f, 0.716567f}, {-0.442863f, -0.238856f, 0.864188f}, 
{-0.587785f, -0.425325f, 0.688191f}, {-0.309017f, -0.500000f, 0.809017f}, 
{-0.147621f, -0.716567f, 0.681718f}, {-0.425325f, -0.688191f, 0.587785f}, 
{-0.162460f, -0.262866f, 0.951056f}, {0.442863f, -0.238856f, 0.864188f}, 
{0.162460f, -0.262866f, 0.951056f}, {0.309017f, -0.500000f, 0.809017f}, 
{0.147621f, -0.716567f, 0.681718f}, {0.000000f, -0.525731f, 0.850651f}, 
{0.425325f, -0.688191f, 0.587785f}, {0.587785f, -0.425325f, 0.688191f}, 
{0.688191f, -0.587785f, 0.425325f}, {-0.955423f, 0.295242f, 0.000000f}, 
{-0.951056f, 0.162460f, 0.262866f}, {-1.000000f, 0.000000f, 0.000000f}, 
{-0.850651f, 0.000000f, 0.525731f}, {-0.955423f, -0.295242f, 0.000000f}, 
{-0.951056f, -0.162460f, 0.262866f}, {-0.864188f, 0.442863f, -0.238856f}, 
{-0.951056f, 0.162460f, -0.262866f}, {-0.809017f, 0.309017f, -0.500000f}, 
{-0.864188f, -0.442863f, -0.238856f}, {-0.951056f, -0.162460f, -0.262866f}, 
{-0.809017f, -0.309017f, -0.500000f}, {-0.681718f, 0.147621f, -0.716567f}, 
{-0.681718f, -0.147621f, -0.716567f}, {-0.850651f, 0.000000f, -0.525731f}, 
{-0.688191f, 0.587785f, -0.425325f}, {-0.587785f, 0.425325f, -0.688191f}, 
{-0.425325f, 0.688191f, -0.587785f}, {-0.425325f, -0.688191f, -0.587785f}, 
{-0.587785f, -0.425325f, -0.688191f}, {-0.688191f, -0.587785f, -0.425325f}
};

//==============================================================

int		Q_rand( int *seed ) {
	*seed = (69069 * *seed + 1);
	return *seed;
}

float	Q_random( int *seed ) {
	return ( Q_rand( seed ) & 0xffff ) / (float)0x10000;
}

float	Q_crandom( int *seed ) {
	return 2.0 * ( Q_random( seed ) - 0.5 );
}

//=======================================================

signed char ClampChar( int i ) {
	if ( i < -128 ) {
		return -128;
	}
	if ( i > 127 ) {
		return 127;
	}
	return i;
}

signed short ClampShort( int i ) {
	if ( i < -32768 ) {
		return -32768;
	}
	if ( i > 0x7fff ) {
		return 0x7fff;
	}
	return i;
}


// this isn't a real cheap function to call!
int DirToByte( vec3_t dir ) {
	int		i, best;
	float	d, bestd;

	if ( !dir ) {
		return 0;
	}

	bestd = 0;
	best = 0;
	for (i=0 ; i<NUMVERTEXNORMALS ; i++)
	{
		d = DotProduct (dir, bytedirs[i]);
		if (d > bestd)
		{
			bestd = d;
			best = i;
		}
	}

	return best;
}

void ByteToDir( int b, vec3_t dir ) {
	if ( b < 0 || b >= NUMVERTEXNORMALS ) {
		VectorCopy( vec3_origin, dir );
		return;
	}
	VectorCopy (bytedirs[b], dir);
}


unsigned ColorBytes3 (float r, float g, float b) {
	unsigned	i;

	( (byte *)&i )[0] = r * 255;
	( (byte *)&i )[1] = g * 255;
	( (byte *)&i )[2] = b * 255;

	return i;
}

unsigned ColorBytes4 (float r, float g, float b, float a) {
	unsigned	i;

	( (byte *)&i )[0] = r * 255;
	( (byte *)&i )[1] = g * 255;
	( (byte *)&i )[2] = b * 255;
	( (byte *)&i )[3] = a * 255;

	return i;
}

float NormalizeColor( const vec3_t in, vec3_t out ) {
	float	max;
	
	max = in[0];
	if ( in[1] > max ) {
		max = in[1];
	}
	if ( in[2] > max ) {
		max = in[2];
	}

	if ( !max ) {
		VectorClear( out );
	} else {
		out[0] = in[0] / max;
		out[1] = in[1] / max;
		out[2] = in[2] / max;
	}
	return max;
}


/*
=====================
PlaneFromPoints

Returns false if the triangle is degenrate.
The normal will point out of the clock for clockwise ordered points
=====================
*/
qboolean PlaneFromPoints( vec4_t plane, const vec3_t a, const vec3_t b, const 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;
}

/*
===============
RotatePointAroundVector

This is not implemented very well...
===============
*/
void RotatePointAroundVector( vec3_t dst, const vec3_t dir, const vec3_t point,
							 float degrees ) {
	float sin_a;
	float cos_a;
	float cos_ia;
	float i_i_ia;
	float j_j_ia;
	float k_k_ia;
	float i_j_ia;
	float i_k_ia;
	float j_k_ia;
	float a_sin;
	float b_sin;
	float c_sin;
	float rot[3][3];

	cos_ia = DEG2RAD(degrees);
	sin_a = sin(cos_ia);
	cos_a = cos(cos_ia);
	cos_ia = 1.0F - cos_a;

	i_i_ia = dir[0] * dir[0] * cos_ia;
	j_j_ia = dir[1] * dir[1] * cos_ia;
	k_k_ia = dir[2] * dir[2] * cos_ia;
	i_j_ia = dir[0] * dir[1] * cos_ia;
	i_k_ia = dir[0] * dir[2] * cos_ia;
	j_k_ia = dir[1] * dir[2] * cos_ia;

	a_sin = dir[0] * sin_a;
	b_sin = dir[1] * sin_a;
	c_sin = dir[2] * sin_a;

	rot[0][0] = i_i_ia + cos_a;
	rot[0][1] = i_j_ia - c_sin;
	rot[0][2] = i_k_ia + b_sin;
	rot[1][0] = i_j_ia + c_sin;
	rot[1][1] = j_j_ia + cos_a;
	rot[1][2] = j_k_ia - a_sin;
	rot[2][0] = i_k_ia - b_sin;
	rot[2][1] = j_k_ia + a_sin;
	rot[2][2] = k_k_ia + cos_a;

	dst[0] = point[0] * rot[0][0] + point[1] * rot[0][1] + point[2] * rot[0][2];
	dst[1] = point[0] * rot[1][0] + point[1] * rot[1][1] + point[2] * rot[1][2];
	dst[2] = point[0] * rot[2][0] + point[1] * rot[2][1] + point[2] * rot[2][2];
}

/*
===============
RotateAroundDirection
===============
*/
void RotateAroundDirection( vec3_t axis[3], vec_t angle ) {
	vec_t scale;

	angle = DEG2RAD( angle );

	// create an arbitrary axis[1]
	PerpendicularVector( axis[ 1 ], axis[ 0 ] );

	// cross to get axis[2]
	CrossProduct( axis[ 0 ], axis[ 1 ], axis[ 2 ] );

	// rotate
	scale = cos( angle );
	VectorScale( axis[ 1 ], scale, axis[ 1 ] );

	scale = sin( angle );
	VectorMA( axis[ 1 ], scale, axis[ 2 ], axis[ 1 ] );

	// recalculate axis[2]
	CrossProduct( axis[ 0 ], axis[ 1 ], axis[ 2 ] );
}



void vectoangles( const vec3_t value1, vec3_t angles ) {
	float	forward;
	float	yaw, pitch;
	
	if ( value1[1] == 0 && value1[0] == 0 ) {
		yaw = 0;
		if ( value1[2] > 0 ) {
			pitch = 90;
		}
		else {
			pitch = 270;
		}
	}
	else {
		if ( value1[0] ) {
			yaw = ( atan2 ( value1[1], value1[0] ) * 180 / M_PI );
		}
		else if ( value1[1] > 0 ) {
			yaw = 90;
		}
		else {
			yaw = 270;
		}
		if ( yaw < 0 ) {
			yaw += 360;
		}

		forward = sqrt ( value1[0]*value1[0] + value1[1]*value1[1] );
		pitch = ( atan2(value1[2], forward) * 180 / M_PI );
		if ( pitch < 0 ) {
			pitch += 360;
		}
	}

	angles[PITCH] = -pitch;
	angles[YAW] = yaw;
	angles[ROLL] = 0;
}


/*
=================
AxisToAngles

Takes an axis (forward + right + up)
and returns angles -- including a roll
=================
*/
void AxisToAngles( vec3_t axis[3], vec3_t angles ) {
	float length1;
	float yaw, pitch, roll = 0.0f;

	if ( axis[0][1] == 0 && axis[0][0] == 0 ) {
		yaw = 0;
		if ( axis[0][2] > 0 ) {
			pitch = 90;
		}
		else {
			pitch = 270;
		}
	}
	else {
		if ( axis[0][0] ) {
			yaw = ( atan2 ( axis[0][1], axis[0][0] ) * 180 / M_PI );
		}
		else if ( axis[0][1] > 0 ) {
			yaw = 90;
		}
		else {
			yaw = 270;
		}
		if ( yaw < 0 ) {
			yaw += 360;
		}

		length1 = sqrt ( axis[0][0]*axis[0][0] + axis[0][1]*axis[0][1] );
		pitch = ( atan2(axis[0][2], length1) * 180 / M_PI );
		if ( pitch < 0 ) {
			pitch += 360;
		}

		roll = ( atan2( axis[1][2], axis[2][2] ) * 180 / M_PI );
		if ( roll < 0 ) {
			roll += 360;
		}
	}

	angles[PITCH] = -pitch;
	angles[YAW] = yaw;
	angles[ROLL] = roll;
}

/*
=================
AnglesToAxis
=================
*/
void AnglesToAxis( const vec3_t angles, vec3_t axis[3] ) {
	vec3_t	right;

	// angle vectors returns "right" instead of "y axis"
	AngleVectors( angles, axis[0], right, axis[2] );
	VectorSubtract( vec3_origin, right, axis[1] );
}

void AxisClear( vec3_t axis[3] ) {
	axis[0][0] = 1;
	axis[0][1] = 0;
	axis[0][2] = 0;
	axis[1][0] = 0;
	axis[1][1] = 1;
	axis[1][2] = 0;
	axis[2][0] = 0;
	axis[2][1] = 0;
	axis[2][2] = 1;
}

void AxisCopy( vec3_t in[3], vec3_t out[3] ) {
	VectorCopy( in[0], out[0] );
	VectorCopy( in[1], out[1] );
	VectorCopy( in[2], out[2] );
}

void ProjectPointOnPlane( vec3_t dst, const vec3_t p, const vec3_t normal )
{
	float d;
	vec3_t n;
	float inv_denom;

	inv_denom = 1.0f / DotProduct( normal, normal );
#ifndef Q3_VM
	assert( Q_fabs(inv_denom) != 0.0f ); // bk010122 - zero vectors get here
#endif
	inv_denom = 1.0f / inv_denom;

	d = DotProduct( normal, p ) * inv_denom;

	n[0] = normal[0] * inv_denom;
	n[1] = normal[1] * inv_denom;
	n[2] = normal[2] * inv_denom;

	dst[0] = p[0] - d * n[0];
	dst[1] = p[1] - d * n[1];
	dst[2] = p[2] - d * n[2];
}

/*
================
MakeNormalVectors

Given a normalized forward vector, create two
other perpendicular vectors
================
*/
void MakeNormalVectors( const vec3_t forward, vec3_t right, vec3_t up) {
	float		d;

	// this rotate and negate guarantees a vector
	// not colinear with the original
	right[1] = -forward[0];
	right[2] = forward[1];
	right[0] = forward[2];

	d = DotProduct (right, forward);
	VectorMA (right, -d, forward, right);
	VectorNormalize (right);
	CrossProduct (right, forward, up);
}


void VectorRotate( vec3_t in, vec3_t matrix[3], vec3_t out )
{
	out[0] = DotProduct( in, matrix[0] );
	out[1] = DotProduct( in, matrix[1] );
	out[2] = DotProduct( in, matrix[2] );
}

//============================================================================

#if !idppc
/*
** float q_rsqrt( float number )
*/
float Q_rsqrt( float number )
{
	union {
		float f;
		int i;
	} t;
	float x2, y;
	const float threehalfs = 1.5F;

	x2 = number * 0.5F;
	t.f  = number;
	t.i  = 0x5f3759df - ( t.i >> 1 );               // what the fuck?
	y  = t.f;
	y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
//	y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

	//assert( !isnan(y) ); // bk010122 - FPE?
	return y;
}

float Q_fabs( float f ) {
	int tmp = * ( int * ) &f;
	tmp &= 0x7FFFFFFF;
	return * ( float * ) &tmp;
}
#endif

//============================================================

/*
===============
LerpAngle

===============
*/
float LerpAngle (float from, float to, float frac) {
	float	a;

	if ( to - from > 180 ) {
		to -= 360;
	}
	if ( to - from < -180 ) {
		to += 360;
	}
	a = from + frac * (to - from);

	return a;
}


/*
=================
AngleSubtract

Always returns a value from -180 to 180
=================
*/
float	AngleSubtract( float a1, float a2 ) {
	float	a;

	a = a1 - a2;
	while ( a > 180 ) {
		a -= 360;
	}
	while ( a < -180 ) {
		a += 360;
	}
	return a;
}


void AnglesSubtract( vec3_t v1, vec3_t v2, vec3_t v3 ) {
	v3[0] = AngleSubtract( v1[0], v2[0] );
	v3[1] = AngleSubtract( v1[1], v2[1] );
	v3[2] = AngleSubtract( v1[2], v2[2] );
}


float	AngleMod(float a) {
	a = (360.0/65536) * ((int)(a*(65536/360.0)) & 65535);
	return a;
}


/*
=================
AngleNormalize360

returns angle normalized to the range [0 <= angle < 360]
=================
*/
float AngleNormalize360 ( float angle ) {
	return (360.0 / 65536) * ((int)(angle * (65536 / 360.0)) & 65535);
}


/*
=================
AngleNormalize180

returns angle normalized to the range [-180 < angle <= 180]
=================
*/
float AngleNormalize180 ( float angle ) {
	angle = AngleNormalize360( angle );
	if ( angle > 180.0 ) {
		angle -= 360.0;
	}
	return angle;
}


/*
=================
AngleDelta

returns the normalized delta from angle1 to angle2
=================
*/
float AngleDelta ( float angle1, float angle2 ) {
	return AngleNormalize180( angle1 - angle2 );
}


//============================================================


/*
=================
SetPlaneSignbits
=================
*/
void SetPlaneSignbits (cplane_t *out) {
	int	bits, j;

	// for fast box on planeside test
	bits = 0;
	for (j=0 ; j<3 ; j++) {
		if (out->normal[j] < 0) {
			bits |= 1<<j;
		}
	}
	out->signbits = bits;
}


/*
==================
BoxOnPlaneSide

Returns 1, 2, or 1 + 2

// this is the slow, general version
int BoxOnPlaneSide2 (vec3_t emins, vec3_t emaxs, struct cplane_s *p)
{
	int		i;
	float	dist1, dist2;
	int		sides;
	vec3_t	corners[2];

	for (i=0 ; i<3 ; i++)
	{
		if (p->normal[i] < 0)
		{
			corners[0][i] = emins[i];
			corners[1][i] = emaxs[i];
		}
		else
		{
			corners[1][i] = emins[i];
			corners[0][i] = emaxs[i];
		}
	}
	dist1 = DotProduct (p->normal, corners[0]) - p->dist;
	dist2 = DotProduct (p->normal, corners[1]) - p->dist;
	sides = 0;
	if (dist1 >= 0)
		sides = 1;
	if (dist2 < 0)
		sides |= 2;

	return sides;
}

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

#if !id386

int BoxOnPlaneSide (vec3_t emins, vec3_t emaxs, struct cplane_s *p)
{
	float	dist1, dist2;
	int		sides;

// fast axial cases
	if (p->type < 3)
	{
		if (p->dist <= emins[p->type])
			return 1;
		if (p->dist >= emaxs[p->type])
			return 2;
		return 3;
	}

// general case
	switch (p->signbits)
	{
	case 0:
		dist1 = p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
		dist2 = p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
		break;
	case 1:
		dist1 = p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
		dist2 = p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
		break;
	case 2:
		dist1 = p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
		dist2 = p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
		break;
	case 3:
		dist1 = p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
		dist2 = p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
		break;
	case 4:
		dist1 = p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
		dist2 = p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
		break;
	case 5:
		dist1 = p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
		dist2 = p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
		break;
	case 6:
		dist1 = p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
		dist2 = p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
		break;
	case 7:
		dist1 = p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
		dist2 = p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
		break;
	default:
		dist1 = dist2 = 0;		// shut up compiler
		break;
	}

	sides = 0;
	if (dist1 >= p->dist)
		sides = 1;
	if (dist2 < p->dist)
		sides |= 2;

	return sides;
}
#elif __GNUC__
// use matha.s
#else
#pragma warning( disable: 4035 )

__declspec( naked ) int BoxOnPlaneSide (vec3_t emins, vec3_t emaxs, struct cplane_s *p)
{
	static int bops_initialized;
	static int Ljmptab[8];

	__asm {

		push ebx
			
		cmp bops_initialized, 1
		je  initialized
		mov bops_initialized, 1
		
		mov Ljmptab[0*4], offset Lcase0
		mov Ljmptab[1*4], offset Lcase1
		mov Ljmptab[2*4], offset Lcase2
		mov Ljmptab[3*4], offset Lcase3
		mov Ljmptab[4*4], offset Lcase4
		mov Ljmptab[5*4], offset Lcase5
		mov Ljmptab[6*4], offset Lcase6
		mov Ljmptab[7*4], offset Lcase7
			
initialized:

		mov edx,dword ptr[4+12+esp]
		mov ecx,dword ptr[4+4+esp]
		xor eax,eax
		mov ebx,dword ptr[4+8+esp]
		mov al,byte ptr[17+edx]
		cmp al,8
		jge Lerror
		fld dword ptr[0+edx]
		fld st(0)
		jmp dword ptr[Ljmptab+eax*4]
Lcase0:
		fmul dword ptr[ebx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ebx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ebx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ecx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
		jmp LSetSides
Lcase1:
		fmul dword ptr[ecx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ebx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ebx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ecx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
		jmp LSetSides
Lcase2:
		fmul dword ptr[ebx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ecx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ebx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ecx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
		jmp LSetSides
Lcase3:
		fmul dword ptr[ecx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ecx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ebx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ecx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
		jmp LSetSides
Lcase4:
		fmul dword ptr[ebx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ebx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ecx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ebx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
		jmp LSetSides
Lcase5:
		fmul dword ptr[ecx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ebx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ecx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ebx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
		jmp LSetSides
Lcase6:
		fmul dword ptr[ebx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ecx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ecx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ecx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ebx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
		jmp LSetSides
Lcase7:
		fmul dword ptr[ecx]
		fld dword ptr[0+4+edx]
		fxch st(2)
		fmul dword ptr[ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[4+ecx]
		fld dword ptr[0+8+edx]
		fxch st(2)
		fmul dword ptr[4+ebx]
		fxch st(2)
		fld st(0)
		fmul dword ptr[8+ecx]
		fxch st(5)
		faddp st(3),st(0)
		fmul dword ptr[8+ebx]
		fxch st(1)
		faddp st(3),st(0)
		fxch st(3)
		faddp st(2),st(0)
LSetSides:
		faddp st(2),st(0)
		fcomp dword ptr[12+edx]
		xor ecx,ecx
		fnstsw ax
		fcomp dword ptr[12+edx]
		and ah,1
		xor ah,1
		add cl,ah
		fnstsw ax
		and ah,1
		add ah,ah
		add cl,ah
		pop ebx
		mov eax,ecx
		ret
Lerror:
		int 3
	}
}
#pragma warning( default: 4035 )

#endif

/*
=================
RadiusFromBounds
=================
*/
float RadiusFromBounds( const vec3_t mins, const vec3_t maxs ) {
	int		i;
	vec3_t	corner;
	float	a, b;

	for (i=0 ; i<3 ; i++) {
		a = fabs( mins[i] );
		b = fabs( maxs[i] );
		corner[i] = a > b ? a : b;
	}

	return VectorLength (corner);
}


void ClearBounds( vec3_t mins, vec3_t maxs ) {
	mins[0] = mins[1] = mins[2] = 99999;
	maxs[0] = maxs[1] = maxs[2] = -99999;
}

void AddPointToBounds( const vec3_t v, vec3_t mins, vec3_t maxs ) {
	if ( v[0] < mins[0] ) {
		mins[0] = v[0];
	}
	if ( v[0] > maxs[0]) {
		maxs[0] = v[0];
	}

	if ( v[1] < mins[1] ) {
		mins[1] = v[1];
	}
	if ( v[1] > maxs[1]) {
		maxs[1] = v[1];
	}

	if ( v[2] < mins[2] ) {
		mins[2] = v[2];
	}
	if ( v[2] > maxs[2]) {
		maxs[2] = v[2];
	}
}

qboolean BoundsIntersect(const vec3_t mins, const vec3_t maxs,
		const vec3_t mins2, const vec3_t maxs2)
{
	if ( maxs[0] < mins2[0] ||
		maxs[1] < mins2[1] ||
		maxs[2] < mins2[2] ||
		mins[0] > maxs2[0] ||
		mins[1] > maxs2[1] ||
		mins[2] > maxs2[2])
	{
		return qfalse;
	}

	return qtrue;
}

qboolean BoundsIntersectSphere(const vec3_t mins, const vec3_t maxs,
		const vec3_t origin, vec_t radius)
{
	if ( origin[0] - radius > maxs[0] ||
		origin[0] + radius < mins[0] ||
		origin[1] - radius > maxs[1] ||
		origin[1] + radius < mins[1] ||
		origin[2] - radius > maxs[2] ||
		origin[2] + radius < mins[2])
	{
		return qfalse;
	}

	return qtrue;
}

qboolean BoundsIntersectPoint(const vec3_t mins, const vec3_t maxs,
		const vec3_t origin)
{
	if ( origin[0] > maxs[0] ||
		origin[0] < mins[0] ||
		origin[1] > maxs[1] ||
		origin[1] < mins[1] ||
		origin[2] > maxs[2] ||
		origin[2] < mins[2])
	{
		return qfalse;
	}

	return qtrue;
}

vec_t VectorNormalize( vec3_t v ) {
	// NOTE: TTimo - Apple G4 altivec source uses double?
	float	length, ilength;

	length = v[0]*v[0] + v[1]*v[1] + v[2]*v[2];
	length = sqrt (length);

	if ( length ) {
		ilength = 1/length;
		v[0] *= ilength;
		v[1] *= ilength;
		v[2] *= ilength;
	}
		
	return length;
}

vec_t VectorNormalize2( const vec3_t v, vec3_t out) {
	float	length, ilength;

	length = v[0]*v[0] + v[1]*v[1] + v[2]*v[2];
	length = sqrt (length);

	if (length)
	{
#ifndef Q3_VM // bk0101022 - FPE related
//	  assert( ((Q_fabs(v[0])!=0.0f) || (Q_fabs(v[1])!=0.0f) || (Q_fabs(v[2])!=0.0f)) );
#endif
		ilength = 1/length;
		out[0] = v[0]*ilength;
		out[1] = v[1]*ilength;
		out[2] = v[2]*ilength;
	} else {
#ifndef Q3_VM // bk0101022 - FPE related
//	  assert( ((Q_fabs(v[0])==0.0f) && (Q_fabs(v[1])==0.0f) && (Q_fabs(v[2])==0.0f)) );
#endif
		VectorClear( out );
	}
		
	return length;

}

void _VectorMA( const vec3_t veca, float scale, const vec3_t vecb, vec3_t vecc) {
	vecc[0] = veca[0] + scale*vecb[0];
	vecc[1] = veca[1] + scale*vecb[1];
	vecc[2] = veca[2] + scale*vecb[2];
}


vec_t _DotProduct( const vec3_t v1, const vec3_t v2 ) {
	return v1[0]*v2[0] + v1[1]*v2[1] + v1[2]*v2[2];
}

void _VectorSubtract( const vec3_t veca, const vec3_t vecb, vec3_t out ) {
	out[0] = veca[0]-vecb[0];
	out[1] = veca[1]-vecb[1];
	out[2] = veca[2]-vecb[2];
}

void _VectorAdd( const vec3_t veca, const vec3_t vecb, vec3_t out ) {
	out[0] = veca[0]+vecb[0];
	out[1] = veca[1]+vecb[1];
	out[2] = veca[2]+vecb[2];
}

void _VectorCopy( const vec3_t in, vec3_t out ) {
	out[0] = in[0];
	out[1] = in[1];
	out[2] = in[2];
}

void _VectorScale( const vec3_t in, vec_t scale, vec3_t out ) {
	out[0] = in[0]*scale;
	out[1] = in[1]*scale;
	out[2] = in[2]*scale;
}

void Vector4Scale( const vec4_t in, vec_t scale, vec4_t out ) {
	out[0] = in[0]*scale;
	out[1] = in[1]*scale;
	out[2] = in[2]*scale;
	out[3] = in[3]*scale;
}


int Q_log2( int val ) {
	int answer;

	answer = 0;
	while ( ( val>>=1 ) != 0 ) {
		answer++;
	}
	return answer;
}



/*
=================
PlaneTypeForNormal
=================
*/
/*
int	PlaneTypeForNormal (vec3_t normal) {
	if ( normal[0] == 1.0 )
		return PLANE_X;
	if ( normal[1] == 1.0 )
		return PLANE_Y;
	if ( normal[2] == 1.0 )
		return PLANE_Z;
	
	return PLANE_NON_AXIAL;
}
*/


/*
================
MatrixMultiply
================
*/
void MatrixMultiply(float in1[3][3], float in2[3][3], float out[3][3]) {
	out[0][0] = in1[0][0] * in2[0][0] + in1[0][1] * in2[1][0] +
				in1[0][2] * in2[2][0];
	out[0][1] = in1[0][0] * in2[0][1] + in1[0][1] * in2[1][1] +
				in1[0][2] * in2[2][1];
	out[0][2] = in1[0][0] * in2[0][2] + in1[0][1] * in2[1][2] +
				in1[0][2] * in2[2][2];
	out[1][0] = in1[1][0] * in2[0][0] + in1[1][1] * in2[1][0] +
				in1[1][2] * in2[2][0];
	out[1][1] = in1[1][0] * in2[0][1] + in1[1][1] * in2[1][1] +
				in1[1][2] * in2[2][1];
	out[1][2] = in1[1][0] * in2[0][2] + in1[1][1] * in2[1][2] +
				in1[1][2] * in2[2][2];
	out[2][0] = in1[2][0] * in2[0][0] + in1[2][1] * in2[1][0] +
				in1[2][2] * in2[2][0];
	out[2][1] = in1[2][0] * in2[0][1] + in1[2][1] * in2[1][1] +
				in1[2][2] * in2[2][1];
	out[2][2] = in1[2][0] * in2[0][2] + in1[2][1] * in2[1][2] +
				in1[2][2] * in2[2][2];
}

/*
================
VectorMatrixMultiply
================
*/
void VectorMatrixMultiply( const vec3_t p, vec3_t m[ 3 ], vec3_t out )
{
	out[ 0 ] = m[ 0 ][ 0 ] * p[ 0 ] + m[ 1 ][ 0 ] * p[ 1 ] + m[ 2 ][ 0 ] * p[ 2 ];
	out[ 1 ] = m[ 0 ][ 1 ] * p[ 0 ] + m[ 1 ][ 1 ] * p[ 1 ] + m[ 2 ][ 1 ] * p[ 2 ];
	out[ 2 ] = m[ 0 ][ 2 ] * p[ 0 ] + m[ 1 ][ 2 ] * p[ 1 ] + m[ 2 ][ 2 ] * p[ 2 ];
}


void AngleVectors( const vec3_t angles, vec3_t forward, vec3_t right, vec3_t up) {
	float		angle;
	static float		sr, sp, sy, cr, cp, cy;
	// static to help MS compiler fp bugs

	angle = angles[YAW] * (M_PI*2 / 360);
	sy = sin(angle);
	cy = cos(angle);
	angle = angles[PITCH] * (M_PI*2 / 360);
	sp = sin(angle);
	cp = cos(angle);
	angle = angles[ROLL] * (M_PI*2 / 360);
	sr = sin(angle);
	cr = cos(angle);

	if (forward)
	{
		forward[0] = cp*cy;
		forward[1] = cp*sy;
		forward[2] = -sp;
	}
	if (right)
	{
		right[0] = (-1*sr*sp*cy+-1*cr*-sy);
		right[1] = (-1*sr*sp*sy+-1*cr*cy);
		right[2] = -1*sr*cp;
	}
	if (up)
	{
		up[0] = (cr*sp*cy+-sr*-sy);
		up[1] = (cr*sp*sy+-sr*cy);
		up[2] = cr*cp;
	}
}

/*
** assumes "src" is normalized
*/
void PerpendicularVector( vec3_t dst, const vec3_t src )
{
	int	pos;
	int i;
	float minelem = 1.0F;
	vec3_t tempvec;

	/*
	** find the smallest magnitude axially aligned vector
	*/
	for ( pos = 0, i = 0; i < 3; i++ )
	{
		if ( fabs( src[i] ) < minelem )
		{
			pos = i;
			minelem = fabs( src[i] );
		}
	}
	tempvec[0] = tempvec[1] = tempvec[2] = 0.0F;
	tempvec[pos] = 1.0F;

	/*
	** project the point onto the plane defined by src
	*/
	ProjectPointOnPlane( dst, tempvec, src );

	/*
	** normalize the result
	*/
	VectorNormalize( dst );
}

/*
=================
pointToLineDistance

Distance from a point to some line
=================
*/
float pointToLineDistance( const vec3_t p0, const vec3_t p1, const vec3_t p2 )
{
	vec3_t	v, w, y;
	float	 c1, c2;

	VectorSubtract( p2, p1, v );
	VectorSubtract( p1, p0, w );

	CrossProduct( w, v, y );
	c1 = VectorLength( y );
	c2 = VectorLength( v );

	if( c2 == 0.0f )
		return 0.0f;
	else
		return c1 / c2;
}

/*
=================
GetPerpendicularViewVector

Used to find an "up" vector for drawing a sprite so that it always faces the view as best as possible
=================
*/
void GetPerpendicularViewVector( const vec3_t point, const vec3_t p1, const vec3_t p2, vec3_t up )
{
	vec3_t	v1, v2;

	VectorSubtract( point, p1, v1 );
	VectorNormalize( v1 );

	VectorSubtract( point, p2, v2 );
	VectorNormalize( v2 );

	CrossProduct( v1, v2, up );
	VectorNormalize( up );
}

/*
================
ProjectPointOntoVector
================
*/
void ProjectPointOntoVector( vec3_t point, vec3_t vStart, vec3_t vEnd, vec3_t vProj )
{
	vec3_t pVec, vec;

	VectorSubtract( point, vStart, pVec );
	VectorSubtract( vEnd, vStart, vec );
	VectorNormalize( vec );
	// project onto the directional vector for this segment
	VectorMA( vStart, DotProduct( pVec, vec ), vec, vProj );
}

/*
================
VectorMaxComponent

Return the biggest component of some vector
================
*/
float VectorMaxComponent( vec3_t v )
{
	float biggest = v[ 0 ];

	if( v[ 1 ] > biggest )
		biggest = v[ 1 ];

	if( v[ 2 ] > biggest )
		biggest = v[ 2 ];

	return biggest;
}

/*
================
VectorMinComponent

Return the smallest component of some vector
================
*/
float VectorMinComponent( vec3_t v )
{
	float smallest = v[ 0 ];

	if( v[ 1 ] < smallest )
		smallest = v[ 1 ];

	if( v[ 2 ] < smallest )
		smallest = v[ 2 ];

	return smallest;
}


#define LINE_DISTANCE_EPSILON 1e-05f

/*
================
DistanceBetweenLineSegmentsSquared

Return the smallest distance between two line segments, squared
================
*/
vec_t DistanceBetweenLineSegmentsSquared(
    const vec3_t sP0, const vec3_t sP1,
    const vec3_t tP0, const vec3_t tP1,
    float *s, float *t )
{
  vec3_t  sMag, tMag, diff;
  float   a, b, c, d, e;
  float   D;
  float   sN, sD;
  float   tN, tD;
  vec3_t  separation;

  VectorSubtract( sP1, sP0, sMag );
  VectorSubtract( tP1, tP0, tMag );
  VectorSubtract( sP0, tP0, diff );
  a = DotProduct( sMag, sMag );
  b = DotProduct( sMag, tMag );
  c = DotProduct( tMag, tMag );
  d = DotProduct( sMag, diff );
  e = DotProduct( tMag, diff );
  sD = tD = D = a * c - b * b;

  if( D < LINE_DISTANCE_EPSILON )
  {
    // the lines are almost parallel
    sN = 0.0;   // force using point P0 on segment S1
    sD = 1.0;   // to prevent possible division by 0.0 later
    tN = e;
    tD = c;
  }
  else
  {
    // get the closest points on the infinite lines
    sN = ( b * e - c * d );
    tN = ( a * e - b * d );

    if( sN < 0.0 )
    {
      // sN < 0 => the s=0 edge is visible
      sN = 0.0;
      tN = e;
      tD = c;
    }
    else if( sN > sD )
    {
      // sN > sD => the s=1 edge is visible
      sN = sD;
      tN = e + b;
      tD = c;
    }
  }

  if( tN < 0.0 )
  {
    // tN < 0 => the t=0 edge is visible
    tN = 0.0;

    // recompute sN for this edge
    if( -d < 0.0 )
      sN = 0.0;
    else if( -d > a )
      sN = sD;
    else
    {
      sN = -d;
      sD = a;
    }
  }
  else if( tN > tD )
  {
    // tN > tD => the t=1 edge is visible
    tN = tD;

    // recompute sN for this edge
    if( ( -d + b ) < 0.0 )
      sN = 0;
    else if( ( -d + b ) > a )
      sN = sD;
    else
    {
      sN = ( -d + b );
      sD = a;
    }
  }

  // finally do the division to get *s and *t
  *s = ( fabs( sN ) < LINE_DISTANCE_EPSILON ? 0.0 : sN / sD );
  *t = ( fabs( tN ) < LINE_DISTANCE_EPSILON ? 0.0 : tN / tD );

  // get the difference of the two closest points
  VectorScale( sMag, *s, sMag );
  VectorScale( tMag, *t, tMag );
  VectorAdd( diff, sMag, separation );
  VectorSubtract( separation, tMag, separation );

  return VectorLengthSquared( separation );
}

/*
================
DistanceBetweenLineSegments

Return the smallest distance between two line segments
================
*/
vec_t DistanceBetweenLineSegments(
    const vec3_t sP0, const vec3_t sP1,
    const vec3_t tP0, const vec3_t tP1,
    float *s, float *t )
{
  return (vec_t)sqrt( DistanceBetweenLineSegmentsSquared(
        sP0, sP1, tP0, tP1, s, t ) );
}

/*
=================
Q_isnan

Don't pass doubles to this
================
*/
int Q_isnan( float x )
{
	union
	{
		float f;
		unsigned int i;
	} t;

	t.f = x;
	t.i &= 0x7FFFFFFF;
	t.i = 0x7F800000 - t.i;

	return (int)( (unsigned int)t.i >> 31 );
}