mirror of
https://github.com/ZDoom/Raze.git
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293 lines
9.2 KiB
C
293 lines
9.2 KiB
C
/*
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** SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
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** Copyright (C) [dates of first publication] Silicon Graphics, Inc.
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** All Rights Reserved.
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**
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** Permission is hereby granted, free of charge, to any person obtaining a copy
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** of this software and associated documentation files (the "Software"), to deal
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** in the Software without restriction, including without limitation the rights
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** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
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** of the Software, and to permit persons to whom the Software is furnished to do so,
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** subject to the following conditions:
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**
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** The above copyright notice including the dates of first publication and either this
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** permission notice or a reference to http://oss.sgi.com/projects/FreeB/ shall be
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** included in all copies or substantial portions of the Software.
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**
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** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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** INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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** PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL SILICON GRAPHICS, INC.
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** BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
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** OR OTHER DEALINGS IN THE SOFTWARE.
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**
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** Except as contained in this notice, the name of Silicon Graphics, Inc. shall not
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** be used in advertising or otherwise to promote the sale, use or other dealings in
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** this Software without prior written authorization from Silicon Graphics, Inc.
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*/
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/*
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** Author: Eric Veach, July 1994.
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*/
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//#include "tesos.h"
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#include <assert.h>
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#include "mesh.h"
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#include "geom.h"
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#include <math.h>
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int tesvertLeq( TESSvertex *u, TESSvertex *v )
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{
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/* Returns TRUE if u is lexicographically <= v. */
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return VertLeq( u, v );
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}
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TESSreal tesedgeEval( TESSvertex *u, TESSvertex *v, TESSvertex *w )
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{
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/* Given three vertices u,v,w such that VertLeq(u,v) && VertLeq(v,w),
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* evaluates the t-coord of the edge uw at the s-coord of the vertex v.
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* Returns v->t - (uw)(v->s), ie. the signed distance from uw to v.
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* If uw is vertical (and thus passes thru v), the result is zero.
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*
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* The calculation is extremely accurate and stable, even when v
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* is very close to u or w. In particular if we set v->t = 0 and
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* let r be the negated result (this evaluates (uw)(v->s)), then
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* r is guaranteed to satisfy MIN(u->t,w->t) <= r <= MAX(u->t,w->t).
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*/
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TESSreal gapL, gapR;
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assert( VertLeq( u, v ) && VertLeq( v, w ));
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gapL = v->s - u->s;
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gapR = w->s - v->s;
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if( gapL + gapR > 0 ) {
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if( gapL < gapR ) {
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return (v->t - u->t) + (u->t - w->t) * (gapL / (gapL + gapR));
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} else {
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return (v->t - w->t) + (w->t - u->t) * (gapR / (gapL + gapR));
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}
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}
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/* vertical line */
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return 0;
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}
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TESSreal tesedgeSign( TESSvertex *u, TESSvertex *v, TESSvertex *w )
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{
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/* Returns a number whose sign matches EdgeEval(u,v,w) but which
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* is cheaper to evaluate. Returns > 0, == 0 , or < 0
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* as v is above, on, or below the edge uw.
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*/
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TESSreal gapL, gapR;
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assert( VertLeq( u, v ) && VertLeq( v, w ));
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gapL = v->s - u->s;
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gapR = w->s - v->s;
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if( gapL + gapR > 0 ) {
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return (v->t - w->t) * gapL + (v->t - u->t) * gapR;
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}
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/* vertical line */
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return 0;
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}
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/***********************************************************************
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* Define versions of EdgeSign, EdgeEval with s and t transposed.
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*/
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TESSreal testransEval( TESSvertex *u, TESSvertex *v, TESSvertex *w )
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{
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/* Given three vertices u,v,w such that TransLeq(u,v) && TransLeq(v,w),
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* evaluates the t-coord of the edge uw at the s-coord of the vertex v.
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* Returns v->s - (uw)(v->t), ie. the signed distance from uw to v.
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* If uw is vertical (and thus passes thru v), the result is zero.
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*
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* The calculation is extremely accurate and stable, even when v
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* is very close to u or w. In particular if we set v->s = 0 and
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* let r be the negated result (this evaluates (uw)(v->t)), then
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* r is guaranteed to satisfy MIN(u->s,w->s) <= r <= MAX(u->s,w->s).
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*/
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TESSreal gapL, gapR;
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assert( TransLeq( u, v ) && TransLeq( v, w ));
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gapL = v->t - u->t;
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gapR = w->t - v->t;
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if( gapL + gapR > 0 ) {
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if( gapL < gapR ) {
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return (v->s - u->s) + (u->s - w->s) * (gapL / (gapL + gapR));
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} else {
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return (v->s - w->s) + (w->s - u->s) * (gapR / (gapL + gapR));
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}
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}
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/* vertical line */
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return 0;
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}
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TESSreal testransSign( TESSvertex *u, TESSvertex *v, TESSvertex *w )
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{
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/* Returns a number whose sign matches TransEval(u,v,w) but which
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* is cheaper to evaluate. Returns > 0, == 0 , or < 0
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* as v is above, on, or below the edge uw.
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*/
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TESSreal gapL, gapR;
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assert( TransLeq( u, v ) && TransLeq( v, w ));
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gapL = v->t - u->t;
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gapR = w->t - v->t;
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if( gapL + gapR > 0 ) {
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return (v->s - w->s) * gapL + (v->s - u->s) * gapR;
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}
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/* vertical line */
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return 0;
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}
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int tesvertCCW( TESSvertex *u, TESSvertex *v, TESSvertex *w )
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{
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/* For almost-degenerate situations, the results are not reliable.
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* Unless the floating-point arithmetic can be performed without
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* rounding errors, *any* implementation will give incorrect results
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* on some degenerate inputs, so the client must have some way to
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* handle this situation.
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*/
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return (u->s*(v->t - w->t) + v->s*(w->t - u->t) + w->s*(u->t - v->t)) >= 0;
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}
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/* Given parameters a,x,b,y returns the value (b*x+a*y)/(a+b),
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* or (x+y)/2 if a==b==0. It requires that a,b >= 0, and enforces
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* this in the rare case that one argument is slightly negative.
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* The implementation is extremely stable numerically.
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* In particular it guarantees that the result r satisfies
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* MIN(x,y) <= r <= MAX(x,y), and the results are very accurate
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* even when a and b differ greatly in magnitude.
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*/
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#define RealInterpolate(a,x,b,y) \
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(a = (a < 0) ? 0 : a, b = (b < 0) ? 0 : b, \
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((a <= b) ? ((b == 0) ? ((x+y) / 2) \
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: (x + (y-x) * (a/(a+b)))) \
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: (y + (x-y) * (b/(a+b)))))
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#ifndef FOR_TRITE_TEST_PROGRAM
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#define Interpolate(a,x,b,y) RealInterpolate(a,x,b,y)
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#else
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/* Claim: the ONLY property the sweep algorithm relies on is that
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* MIN(x,y) <= r <= MAX(x,y). This is a nasty way to test that.
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*/
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#include <stdlib.h>
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extern int RandomInterpolate;
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double Interpolate( double a, double x, double b, double y)
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{
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printf("*********************%d\n",RandomInterpolate);
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if( RandomInterpolate ) {
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a = 1.2 * drand48() - 0.1;
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a = (a < 0) ? 0 : ((a > 1) ? 1 : a);
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b = 1.0 - a;
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}
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return RealInterpolate(a,x,b,y);
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}
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#endif
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#define Swap(a,b) if (1) { TESSvertex *t = a; a = b; b = t; } else
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void tesedgeIntersect( TESSvertex *o1, TESSvertex *d1,
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TESSvertex *o2, TESSvertex *d2,
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TESSvertex *v )
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/* Given edges (o1,d1) and (o2,d2), compute their point of intersection.
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* The computed point is guaranteed to lie in the intersection of the
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* bounding rectangles defined by each edge.
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*/
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{
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TESSreal z1, z2;
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/* This is certainly not the most efficient way to find the intersection
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* of two line segments, but it is very numerically stable.
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*
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* Strategy: find the two middle vertices in the VertLeq ordering,
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* and interpolate the intersection s-value from these. Then repeat
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* using the TransLeq ordering to find the intersection t-value.
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*/
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if( ! VertLeq( o1, d1 )) { Swap( o1, d1 ); }
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if( ! VertLeq( o2, d2 )) { Swap( o2, d2 ); }
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if( ! VertLeq( o1, o2 )) { Swap( o1, o2 ); Swap( d1, d2 ); }
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if( ! VertLeq( o2, d1 )) {
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/* Technically, no intersection -- do our best */
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v->s = (o2->s + d1->s) / 2;
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} else if( VertLeq( d1, d2 )) {
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/* Interpolate between o2 and d1 */
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z1 = EdgeEval( o1, o2, d1 );
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z2 = EdgeEval( o2, d1, d2 );
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if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
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v->s = Interpolate( z1, o2->s, z2, d1->s );
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} else {
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/* Interpolate between o2 and d2 */
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z1 = EdgeSign( o1, o2, d1 );
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z2 = -EdgeSign( o1, d2, d1 );
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if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
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v->s = Interpolate( z1, o2->s, z2, d2->s );
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}
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/* Now repeat the process for t */
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if( ! TransLeq( o1, d1 )) { Swap( o1, d1 ); }
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if( ! TransLeq( o2, d2 )) { Swap( o2, d2 ); }
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if( ! TransLeq( o1, o2 )) { Swap( o1, o2 ); Swap( d1, d2 ); }
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if( ! TransLeq( o2, d1 )) {
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/* Technically, no intersection -- do our best */
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v->t = (o2->t + d1->t) / 2;
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} else if( TransLeq( d1, d2 )) {
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/* Interpolate between o2 and d1 */
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z1 = TransEval( o1, o2, d1 );
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z2 = TransEval( o2, d1, d2 );
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if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
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v->t = Interpolate( z1, o2->t, z2, d1->t );
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} else {
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/* Interpolate between o2 and d2 */
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z1 = TransSign( o1, o2, d1 );
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z2 = -TransSign( o1, d2, d1 );
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if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
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v->t = Interpolate( z1, o2->t, z2, d2->t );
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}
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}
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TESSreal inCircle( TESSvertex *v, TESSvertex *v0, TESSvertex *v1, TESSvertex *v2 ) {
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TESSreal adx, ady, bdx, bdy, cdx, cdy;
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TESSreal abdet, bcdet, cadet;
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TESSreal alift, blift, clift;
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adx = v0->s - v->s;
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ady = v0->t - v->t;
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bdx = v1->s - v->s;
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bdy = v1->t - v->t;
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cdx = v2->s - v->s;
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cdy = v2->t - v->t;
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abdet = adx * bdy - bdx * ady;
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bcdet = bdx * cdy - cdx * bdy;
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cadet = cdx * ady - adx * cdy;
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alift = adx * adx + ady * ady;
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blift = bdx * bdx + bdy * bdy;
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clift = cdx * cdx + cdy * cdy;
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return alift * bcdet + blift * cadet + clift * abdet;
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}
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/*
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Returns 1 is edge is locally delaunay
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*/
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int tesedgeIsLocallyDelaunay( TESShalfEdge *e )
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{
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return inCircle(e->Sym->Lnext->Lnext->Org, e->Lnext->Org, e->Lnext->Lnext->Org, e->Org) < 0;
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}
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