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![Francois Gouget](/assets/img/avatar_default.png)
Signed-off-by: Francois Gouget <fgouget@free.fr> Signed-off-by: Alexandre Julliard <julliard@winehq.org>
245 lines
8.1 KiB
C
245 lines
8.1 KiB
C
/*
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* SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
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* Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice including the dates of first publication and
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* either this permission notice or a reference to
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* http://oss.sgi.com/projects/FreeB/
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* shall be 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
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
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* OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* Except as contained in this notice, the name of Silicon Graphics, Inc.
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* shall not be used in advertising or otherwise to promote the sale, use or
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* other dealings in this Software without prior written authorization from
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* 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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*/
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#include <stdarg.h>
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#include <assert.h>
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#include "windef.h"
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#include "winbase.h"
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#include "tess.h"
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int __gl_vertLeq( GLUvertex *u, GLUvertex *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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GLdouble __gl_edgeEval( GLUvertex *u, GLUvertex *v, GLUvertex *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), i.e. the signed distance from uw to v.
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* If uw is vertical (and thus passes through 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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GLdouble 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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GLdouble __gl_edgeSign( GLUvertex *u, GLUvertex *v, GLUvertex *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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GLdouble 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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GLdouble __gl_transEval( GLUvertex *u, GLUvertex *v, GLUvertex *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), i.e. the signed distance from uw to v.
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* If uw is vertical (and thus passes through 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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GLdouble 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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GLdouble __gl_transSign( GLUvertex *u, GLUvertex *v, GLUvertex *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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GLdouble 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 __gl_vertCCW( GLUvertex *u, GLUvertex *v, GLUvertex *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 Interpolate(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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#define Swap(a,b) do { GLUvertex *t = a; a = b; b = t; } while (0)
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void __gl_edgeIntersect( GLUvertex *o1, GLUvertex *d1,
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GLUvertex *o2, GLUvertex *d2,
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GLUvertex *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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GLdouble 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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