cm_polylib.c

quakeIII源码这个不用我多说吧

/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena 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.

Quake III Arena 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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

// this is only used for visualization tools in cm_ debug functions


#include "cm_local.h"


// counters are only bumped when running single threaded,
// because they are an awefull coherence problem
int	c_active_windings;
int	c_peak_windings;
int	c_winding_allocs;
int	c_winding_points;

void pw(winding_t *w)
{
	int		i;
	for (i=0 ; i<w->numpoints ; i++)
		printf ("(%5.1f, %5.1f, %5.1f)\n",w->p[i][0], w->p[i][1],w->p[i][2]);
}


/*
=============
AllocWinding
=============
*/
winding_t	*AllocWinding (int points)
{
	winding_t	*w;
	int			s;

	c_winding_allocs++;
	c_winding_points += points;
	c_active_windings++;
	if (c_active_windings > c_peak_windings)
		c_peak_windings = c_active_windings;

	s = sizeof(vec_t)*3*points + sizeof(int);
	w = Z_Malloc (s);
	Com_Memset (w, 0, s); 
	return w;
}

void FreeWinding (winding_t *w)
{
	if (*(unsigned *)w == 0xdeaddead)
		Com_Error (ERR_FATAL, "FreeWinding: freed a freed winding");
	*(unsigned *)w = 0xdeaddead;

	c_active_windings--;
	Z_Free (w);
}

/*
============
RemoveColinearPoints
============
*/
int	c_removed;

void	RemoveColinearPoints (winding_t *w)
{
	int		i, j, k;
	vec3_t	v1, v2;
	int		nump;
	vec3_t	p[MAX_POINTS_ON_WINDING];

	nump = 0;
	for (i=0 ; i<w->numpoints ; i++)
	{
		j = (i+1)%w->numpoints;
		k = (i+w->numpoints-1)%w->numpoints;
		VectorSubtract (w->p[j], w->p[i], v1);
		VectorSubtract (w->p[i], w->p[k], v2);
		VectorNormalize2(v1,v1);
		VectorNormalize2(v2,v2);
		if (DotProduct(v1, v2) < 0.999)
		{
			VectorCopy (w->p[i], p[nump]);
			nump++;
		}
	}

	if (nump == w->numpoints)
		return;

	c_removed += w->numpoints - nump;
	w->numpoints = nump;
	Com_Memcpy (w->p, p, nump*sizeof(p[0]));
}

/*
============
WindingPlane
============
*/
void WindingPlane (winding_t *w, vec3_t normal, vec_t *dist)
{
	vec3_t	v1, v2;

	VectorSubtract (w->p[1], w->p[0], v1);
	VectorSubtract (w->p[2], w->p[0], v2);
	CrossProduct (v2, v1, normal);
	VectorNormalize2(normal, normal);
	*dist = DotProduct (w->p[0], normal);

}

/*
=============
WindingArea
=============
*/
vec_t	WindingArea (winding_t *w)
{
	int		i;
	vec3_t	d1, d2, cross;
	vec_t	total;

	total = 0;
	for (i=2 ; i<w->numpoints ; i++)
	{
		VectorSubtract (w->p[i-1], w->p[0], d1);
		VectorSubtract (w->p[i], w->p[0], d2);
		CrossProduct (d1, d2, cross);
		total += 0.5 * VectorLength ( cross );
	}
	return total;
}

/*
=============
WindingBounds
=============
*/
void	WindingBounds (winding_t *w, vec3_t mins, vec3_t maxs)
{
	vec_t	v;
	int		i,j;

	mins[0] = mins[1] = mins[2] = MAX_MAP_BOUNDS;
	maxs[0] = maxs[1] = maxs[2] = -MAX_MAP_BOUNDS;

	for (i=0 ; i<w->numpoints ; i++)
	{
		for (j=0 ; j<3 ; j++)
		{
			v = w->p[i][j];
			if (v < mins[j])
				mins[j] = v;
			if (v > maxs[j])
				maxs[j] = v;
		}
	}
}

/*
=============
WindingCenter
=============
*/
void	WindingCenter (winding_t *w, vec3_t center)
{
	int		i;
	float	scale;

	VectorCopy (vec3_origin, center);
	for (i=0 ; i<w->numpoints ; i++)
		VectorAdd (w->p[i], center, center);

	scale = 1.0/w->numpoints;
	VectorScale (center, scale, center);
}

/*
=================
BaseWindingForPlane
=================
*/
winding_t *BaseWindingForPlane (vec3_t normal, vec_t dist)
{
	int		i, x;
	vec_t	max, v;
	vec3_t	org, vright, vup;
	winding_t	*w;
	
// find the major axis

	max = -MAX_MAP_BOUNDS;
	x = -1;
	for (i=0 ; i<3; i++)
	{
		v = fabs(normal[i]);
		if (v > max)
		{
			x = i;
			max = v;
		}
	}
	if (x==-1)
		Com_Error (ERR_DROP, "BaseWindingForPlane: no axis found");
		
	VectorCopy (vec3_origin, vup);	
	switch (x)
	{
	case 0:
	case 1:
		vup[2] = 1;
		break;		
	case 2:
		vup[0] = 1;
		break;		
	}

	v = DotProduct (vup, normal);
	VectorMA (vup, -v, normal, vup);
	VectorNormalize2(vup, vup);
		
	VectorScale (normal, dist, org);
	
	CrossProduct (vup, normal, vright);
	
	VectorScale (vup, MAX_MAP_BOUNDS, vup);
	VectorScale (vright, MAX_MAP_BOUNDS, vright);

// project a really big	axis aligned box onto the plane
	w = AllocWinding (4);
	
	VectorSubtract (org, vright, w->p[0]);
	VectorAdd (w->p[0], vup, w->p[0]);
	
	VectorAdd (org, vright, w->p[1]);
	VectorAdd (w->p[1], vup, w->p[1]);
	
	VectorAdd (org, vright, w->p[2]);
	VectorSubtract (w->p[2], vup, w->p[2]);
	
	VectorSubtract (org, vright, w->p[3]);
	VectorSubtract (w->p[3], vup, w->p[3]);
	
	w->numpoints = 4;
	
	return w;	
}

/*
==================
CopyWinding
==================
*/
winding_t	*CopyWinding (winding_t *w)
{
	int			size;
	winding_t	*c;

	c = AllocWinding (w->numpoints);
	size = (int)((winding_t *)0)->p[w->numpoints];
	Com_Memcpy (c, w, size);
	return c;
}

/*
==================
ReverseWinding
==================
*/
winding_t	*ReverseWinding (winding_t *w)
{
	int			i;
	winding_t	*c;

	c = AllocWinding (w->numpoints);
	for (i=0 ; i<w->numpoints ; i++)
	{
		VectorCopy (w->p[w->numpoints-1-i], c->p[i]);
	}
	c->numpoints = w->numpoints;
	return c;
}


/*
=============
ClipWindingEpsilon
=============
*/
void	ClipWindingEpsilon (winding_t *in, vec3_t normal, vec_t dist, 
				vec_t epsilon, winding_t **front, winding_t **back)
{
	vec_t	dists[MAX_POINTS_ON_WINDING+4];
	int		sides[MAX_POINTS_ON_WINDING+4];
	int		counts[3];
	static	vec_t	dot;		// VC 4.2 optimizer bug if not static
	int		i, j;
	vec_t	*p1, *p2;
	vec3_t	mid;
	winding_t	*f, *b;
	int		maxpts;
	
	counts[0] = counts[1] = counts[2] = 0;

// determine sides for each point
	for (i=0 ; i<in->numpoints ; i++)
	{
		dot = DotProduct (in->p[i], normal);
		dot -= dist;
		dists[i] = dot;
		if (dot > epsilon)
			sides[i] = SIDE_FRONT;
		else if (dot < -epsilon)
			sides[i] = SIDE_BACK;
		else
		{
			sides[i] = SIDE_ON;
		}
		counts[sides[i]]++;
	}
	sides[i] = sides[0];
	dists[i] = dists[0];
	
	*front = *back = NULL;

	if (!counts[0])
	{
		*back = CopyWinding (in);
		return;
	}
	if (!counts[1])
	{
		*front = CopyWinding (in);
		return;
	}

	maxpts = in->numpoints+4;	// cant use counts[0]+2 because
								// of fp grouping errors

	*front = f = AllocWinding (maxpts);
	*back = b = AllocWinding (maxpts);
		
	for (i=0 ; i<in->numpoints ; i++)
	{
		p1 = in->p[i];
		
		if (sides[i] == SIDE_ON)
		{
			VectorCopy (p1, f->p[f->numpoints]);
			f->numpoints++;