csg.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
===========================================================================
*/

#include "qbsp.h"

/*

tag all brushes with original contents
brushes may contain multiple contents
there will be no brush overlap after csg phase

*/

int minplanenums[3];
int maxplanenums[3];

//===========================================================================
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
void CheckBSPBrush(bspbrush_t *brush)
{
	int i, j;
	plane_t *plane1, *plane2;

	//check if the brush is convex... flipped planes make a brush non-convex
	for (i = 0; i < brush->numsides; i++)
	{
		for (j = 0; j < brush->numsides; j++)
		{
			if (i == j) continue;
			plane1 = &mapplanes[brush->sides[i].planenum];
			plane2 = &mapplanes[brush->sides[j].planenum];
			//
			if (WindingsNonConvex(brush->sides[i].winding,
									brush->sides[j].winding,
									plane1->normal, plane2->normal,
									plane1->dist, plane2->dist))
			{
				Log_Print("non convex brush");
				break;
			} //end if
		} //end for
	} //end for
	BoundBrush(brush);
	//check for out of bound brushes
	for (i = 0; i < 3; i++)
	{
		if (brush->mins[i] < -MAX_MAP_BOUNDS || brush->maxs[i] > MAX_MAP_BOUNDS)
		{
			Log_Print("brush: bounds out of range\n");
			Log_Print("ob->mins[%d] = %f, ob->maxs[%d] = %f\n", i, brush->mins[i], i, brush->maxs[i]);
			break;
		} //end if
		if (brush->mins[i] > MAX_MAP_BOUNDS || brush->maxs[i] < -MAX_MAP_BOUNDS)
		{
			Log_Print("brush: no visible sides on brush\n");
			Log_Print("ob->mins[%d] = %f, ob->maxs[%d] = %f\n", i, brush->mins[i], i, brush->maxs[i]);
			break;
		} //end if
	} //end for
} //end of the function CheckBSPBrush
//===========================================================================
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
void BSPBrushWindings(bspbrush_t *brush)
{
	int i, j;
	winding_t *w;
	plane_t *plane;

	for (i = 0; i < brush->numsides; i++)
	{
		plane = &mapplanes[brush->sides[i].planenum];
		w = BaseWindingForPlane(plane->normal, plane->dist);
		for (j = 0; j < brush->numsides && w; j++)
		{
			if (i == j) continue;
			plane = &mapplanes[brush->sides[j].planenum^1];
			ChopWindingInPlace(&w, plane->normal, plane->dist, 0); //CLIP_EPSILON);
		} //end for
		brush->sides[i].winding = w;
	} //end for
} //end of the function BSPBrushWindings
//===========================================================================
// NOTE: can't keep brush->original intact
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
bspbrush_t *TryMergeBrushes(bspbrush_t *brush1, bspbrush_t *brush2)
{
	int i, j, k, n, shared;
	side_t *side1, *side2, *cs;
	plane_t *plane1, *plane2;
	bspbrush_t *newbrush;

	//check for bounding box overlapp
	for (i = 0; i < 3; i++)
	{
		if (brush1->mins[i] > brush2->maxs[i] + 2
				|| brush1->maxs[i] < brush2->mins[i] - 2)
		{
			return NULL;
		} //end if
	} //end for
	//
	shared = 0;
	//check if the brush is convex... flipped planes make a brush non-convex
	for (i = 0; i < brush1->numsides; i++)
	{
		side1 = &brush1->sides[i];
		//don't check the "shared" sides
		for (k = 0; k < brush2->numsides; k++)
		{
			side2 = &brush2->sides[k];
			if (side1->planenum == (side2->planenum^1))
			{
				shared++;
				//there may only be ONE shared side
				if (shared > 1) return NULL;
				break;
			} //end if
		} //end for
		if (k < brush2->numsides) continue;
		//
		for (j = 0; j < brush2->numsides; j++)
		{
			side2 = &brush2->sides[j];
			//don't check the "shared" sides
			for (n = 0; n < brush1->numsides; n++)
			{
				side1 = &brush1->sides[n];
				if (side1->planenum == (side2->planenum^1)) break;
			} //end for
			if (n < brush1->numsides) continue;
			//
			side1 = &brush1->sides[i];
			//if the side is in the same plane
			//*
			if (side1->planenum == side2->planenum)
			{
				if (side1->texinfo != TEXINFO_NODE &&
					side2->texinfo != TEXINFO_NODE &&
					side1->texinfo != side2->texinfo) return NULL;
				continue;
			} //end if
			//
			plane1 = &mapplanes[side1->planenum];
			plane2 = &mapplanes[side2->planenum];
			//
			if (WindingsNonConvex(side1->winding, side2->winding,
									plane1->normal, plane2->normal,
									plane1->dist, plane2->dist))
			{
				return NULL;
			} //end if
		} //end for
	} //end for
	newbrush = AllocBrush(brush1->numsides + brush2->numsides);
	newbrush->original = brush1->original;
	newbrush->numsides = 0;
	//newbrush->side = brush1->side;	//brush contents
	//fix texinfos for sides lying in the same plane
	for (i = 0; i < brush1->numsides; i++)
	{
		side1 = &brush1->sides[i];
		//
		for (n = 0; n < brush2->numsides; n++)
		{
			side2 = &brush2->sides[n];
			//if both sides are in the same plane get the texinfo right
			if (side1->planenum == side2->planenum)
			{
				if (side1->texinfo == TEXINFO_NODE) side1->texinfo = side2->texinfo;
				if (side2->texinfo == TEXINFO_NODE) side2->texinfo = side1->texinfo;
			} //end if
		} //end for
	} //end for
	//
	for (i = 0; i < brush1->numsides; i++)
	{
		side1 = &brush1->sides[i];
		//don't add the "shared" sides
		for (n = 0; n < brush2->numsides; n++)
		{
			side2 = &brush2->sides[n];
			if (side1->planenum == (side2->planenum ^ 1)) break;
		} //end for
		if (n < brush2->numsides) continue;
		//
		for (n = 0; n < newbrush->numsides; n++)
		{
			cs = &newbrush->sides[n];
			if (cs->planenum == side1->planenum)
			{
				Log_Print("brush duplicate plane\n");
				break;
			} //end if
		} //end if
		if (n < newbrush->numsides) continue;
		//add this side
		cs = &newbrush->sides[newbrush->numsides];
		newbrush->numsides++;
		*cs = *side1;
	} //end for
	for (j = 0; j < brush2->numsides; j++)
	{
		side2 = &brush2->sides[j];
		for (n = 0; n < brush1->numsides; n++)
		{
			side1 = &brush1->sides[n];
			//if the side is in the same plane
			if (side2->planenum == side1->planenum) break;
			//don't add the "shared" sides
			if (side2->planenum == (side1->planenum ^ 1)) break;
		} //end for
		if (n < brush1->numsides) continue;
		//
		for (n = 0; n < newbrush->numsides; n++)
		{
			cs = &newbrush->sides[n];
			if (cs->planenum == side2->planenum)
			{
				Log_Print("brush duplicate plane\n");
				break;
			} //end if
		} //end if
		if (n < newbrush->numsides) continue;
		//add this side
		cs = &newbrush->sides[newbrush->numsides];
		newbrush->numsides++;
		*cs = *side2;
	} //end for
	BSPBrushWindings(newbrush);
	BoundBrush(newbrush);
	CheckBSPBrush(newbrush);
	return newbrush;
} //end of the function TryMergeBrushes
//===========================================================================
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
bspbrush_t *MergeBrushes(bspbrush_t *brushlist)
{
	int nummerges, merged;
	bspbrush_t *b1, *b2, *tail, *newbrush, *newbrushlist;
	bspbrush_t *lastb2;

	if (!brushlist) return NULL;

	qprintf("%5d brushes merged", nummerges = 0);
	do
	{
		for (tail = brushlist; tail; tail = tail->next)
		{
			if (!tail->next) break;
		} //end for
		merged = 0;
		newbrushlist = NULL;
		for (b1 = brushlist; b1; b1 = brushlist)
		{
			lastb2 = b1;
			for (b2 = b1->next; b2; b2 = b2->next)
			{
				//if the brushes don't have the same contents
				if (b1->original->contents != b2->original->contents ||
					b1->original->expansionbbox != b2->original->expansionbbox) newbrush = NULL;
				else newbrush = TryMergeBrushes(b1, b2);
				if (newbrush)
				{
					tail->next = newbrush;
					lastb2->next = b2->next;
					brushlist = brushlist->next;
					FreeBrush(b1);
					FreeBrush(b2);
					for (tail = brushlist; tail; tail = tail->next)
					{
						if (!tail->next) break;
					} //end for
					merged++;
					qprintf("\r%5d", nummerges++);
					break;
				} //end if
				lastb2 = b2;
			} //end for
			//if b1 can't be merged with any of the other brushes
			if (!b2)
			{
				brushlist = brushlist->next;
				//keep b1
				b1->next = newbrushlist;
				newbrushlist = b1;
			} //end else
		} //end for
		brushlist = newbrushlist;
	} while(merged);
	qprintf("\n");
	return newbrushlist;
} //end of the function MergeBrushes
//===========================================================================
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
void SplitBrush2 (bspbrush_t *brush, int planenum,
	bspbrush_t **front, bspbrush_t **back)
{
	SplitBrush (brush, planenum, front, back);
#if 0
	if (*front && (*front)->sides[(*front)->numsides-1].texinfo == -1)
		(*front)->sides[(*front)->numsides-1].texinfo = (*front)->sides[0].texinfo;	// not -1
	if (*back && (*back)->sides[(*back)->numsides-1].texinfo == -1)
		(*back)->sides[(*back)->numsides-1].texinfo = (*back)->sides[0].texinfo;	// not -1
#endif
} //end of the function SplitBrush2
//===========================================================================
// Returns a list of brushes that remain after B is subtracted from A.
// May by empty if A is contained inside B.
// The originals are undisturbed.
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
bspbrush_t *SubtractBrush (bspbrush_t *a, bspbrush_t *b)
{	// a - b = out (list)
	int		i;
	bspbrush_t	*front, *back;
	bspbrush_t	*out, *in;

	in = a;
	out = NULL;
	for (i = 0; i < b->numsides && in; i++)
	{
		SplitBrush2(in, b->sides[i].planenum, &front, &back);
		if (in != a) FreeBrush(in);
		if (front)
		{	// add to list
			front->next = out;
			out = front;
		} //end if
		in = back;
	} //end for
	if (in)
	{
		FreeBrush (in);
	} //end if
	else
	{	// didn't really intersect
		FreeBrushList (out);
		return a;
	} //end else
	return out;
} //end of the function SubtractBrush
//===========================================================================
// Returns a single brush made up by the intersection of the
// two provided brushes, or NULL if they are disjoint.
//
// The originals are undisturbed.
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
bspbrush_t *IntersectBrush (bspbrush_t *a, bspbrush_t *b)
{
	int		i;
	bspbrush_t	*front, *back;
	bspbrush_t	*in;

	in = a;
	for (i=0 ; i<b->numsides && in ; i++)
	{
		SplitBrush2(in, b->sides[i].planenum, &front, &back);
		if (in != a) FreeBrush(in);
		if (front) FreeBrush(front);
		in = back;
	} //end for

	if (in == a) return NULL;

	in->next = NULL;
	return in;
} //end of the function IntersectBrush
//===========================================================================
// Returns true if the two brushes definately do not intersect.
// There will be false negatives for some non-axial combinations.
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
qboolean BrushesDisjoint (bspbrush_t *a, bspbrush_t *b)
{
	int		i, j;

	// check bounding boxes
	for (i=0 ; i<3 ; i++)
		if (a->mins[i] >= b->maxs[i]
		|| a->maxs[i] <= b->mins[i])
			return true;	// bounding boxes don't overlap

	// check for opposing planes
	for (i=0 ; i<a->numsides ; i++)
	{
		for (j=0 ; j<b->numsides ; j++)
		{
			if (a->sides[i].planenum ==
			(b->sides[j].planenum^1) )
				return true;	// opposite planes, so not touching
		}
	}

	return false;	// might intersect
} //end of the function BrushesDisjoint
//===========================================================================
// Returns a content word for the intersection of two brushes.
// Some combinations will generate a combination (water + clip),
// but most will be the stronger of the two contents.
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
int IntersectionContents (int c1, int c2)
{
	int out;

	out = c1 | c2;

	if (out & CONTENTS_SOLID) out = CONTENTS_SOLID;

	return out;
} //end of the function IntersectionContents
//===========================================================================
// Any planes shared with the box edge will be set to no texinfo
//
// Parameter:				-
// Returns:					-
// Changes Globals:		-
//===========================================================================
bspbrush_t *ClipBrushToBox(bspbrush_t *brush, vec3_t clipmins, vec3_t clipmaxs)
{
	int		i, j;
	bspbrush_t	*front,	*back;
	int		p;

	for (j=0 ; j<2 ; j++)
	{
		if (brush->maxs[j] > clipmaxs[j])
		{
			SplitBrush (brush, maxplanenums[j], &front, &back);
			if (front)
				FreeBrush (front);
			brush = back;
			if (!brush)
				return NULL;
		}
		if (brush->mins[j] < clipmins[j])
		{
			SplitBrush (brush, minplanenums[j], &front, &back);
			if (back)
				FreeBrush (back);
			brush = front;
			if (!brush)
				return NULL;
		}
	}

	// remove any colinear faces

	for (i=0 ; i<brush->numsides ; i++)
	{
		p = brush->sides[i].planenum & ~1;