SGI SI GLU library

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diff --git a/src/glu/sgi/libtess/geom.c b/src/glu/sgi/libtess/geom.c
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+/*
+** License Applicability. Except to the extent portions of this file are
+** made subject to an alternative license as permitted in the SGI Free
+** Software License B, Version 1.1 (the "License"), the contents of this
+** file are subject only to the provisions of the License. You may not use
+** this file except in compliance with the License. You may obtain a copy
+** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
+** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
+** 
+** http://oss.sgi.com/projects/FreeB
+** 
+** Note that, as provided in the License, the Software is distributed on an
+** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
+** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
+** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
+** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
+** 
+** Original Code. The Original Code is: OpenGL Sample Implementation,
+** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
+** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
+** Copyright in any portions created by third parties is as indicated
+** elsewhere herein. All Rights Reserved.
+** 
+** Additional Notice Provisions: The application programming interfaces
+** established by SGI in conjunction with the Original Code are The
+** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
+** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
+** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
+** Window System(R) (Version 1.3), released October 19, 1998. This software
+** was created using the OpenGL(R) version 1.2.1 Sample Implementation
+** published by SGI, but has not been independently verified as being
+** compliant with the OpenGL(R) version 1.2.1 Specification.
+**
+*/
+/*
+** Author: Eric Veach, July 1994.
+**
+** $Date: 2001/03/17 00:25:41 $ $Revision: 1.1 $
+** $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libtess/geom.c,v 1.1 2001/03/17 00:25:41 brianp Exp $
+*/
+
+#include "gluos.h"
+#include <assert.h>
+#include "mesh.h"
+#include "geom.h"
+
+int __gl_vertLeq( GLUvertex *u, GLUvertex *v )
+{
+  /* Returns TRUE if u is lexicographically <= v. */
+
+  return VertLeq( u, v );
+}
+
+GLdouble __gl_edgeEval( GLUvertex *u, GLUvertex *v, GLUvertex *w )
+{
+  /* Given three vertices u,v,w such that VertLeq(u,v) && VertLeq(v,w),
+   * evaluates the t-coord of the edge uw at the s-coord of the vertex v.
+   * Returns v->t - (uw)(v->s), ie. the signed distance from uw to v.
+   * If uw is vertical (and thus passes thru v), the result is zero.
+   *
+   * The calculation is extremely accurate and stable, even when v
+   * is very close to u or w.  In particular if we set v->t = 0 and
+   * let r be the negated result (this evaluates (uw)(v->s)), then
+   * r is guaranteed to satisfy MIN(u->t,w->t) <= r <= MAX(u->t,w->t).
+   */
+  GLdouble gapL, gapR;
+
+  assert( VertLeq( u, v ) && VertLeq( v, w ));
+  
+  gapL = v->s - u->s;
+  gapR = w->s - v->s;
+
+  if( gapL + gapR > 0 ) {
+    if( gapL < gapR ) {
+      return (v->t - u->t) + (u->t - w->t) * (gapL / (gapL + gapR));
+    } else {
+      return (v->t - w->t) + (w->t - u->t) * (gapR / (gapL + gapR));
+    }
+  }
+  /* vertical line */
+  return 0;
+}
+
+GLdouble __gl_edgeSign( GLUvertex *u, GLUvertex *v, GLUvertex *w )
+{
+  /* Returns a number whose sign matches EdgeEval(u,v,w) but which
+   * is cheaper to evaluate.  Returns > 0, == 0 , or < 0
+   * as v is above, on, or below the edge uw.
+   */
+  GLdouble gapL, gapR;
+
+  assert( VertLeq( u, v ) && VertLeq( v, w ));
+  
+  gapL = v->s - u->s;
+  gapR = w->s - v->s;
+
+  if( gapL + gapR > 0 ) {
+    return (v->t - w->t) * gapL + (v->t - u->t) * gapR;
+  }
+  /* vertical line */
+  return 0;
+}
+
+
+/***********************************************************************
+ * Define versions of EdgeSign, EdgeEval with s and t transposed.
+ */
+
+GLdouble __gl_transEval( GLUvertex *u, GLUvertex *v, GLUvertex *w )
+{
+  /* Given three vertices u,v,w such that TransLeq(u,v) && TransLeq(v,w),
+   * evaluates the t-coord of the edge uw at the s-coord of the vertex v.
+   * Returns v->s - (uw)(v->t), ie. the signed distance from uw to v.
+   * If uw is vertical (and thus passes thru v), the result is zero.
+   *
+   * The calculation is extremely accurate and stable, even when v
+   * is very close to u or w.  In particular if we set v->s = 0 and
+   * let r be the negated result (this evaluates (uw)(v->t)), then
+   * r is guaranteed to satisfy MIN(u->s,w->s) <= r <= MAX(u->s,w->s).
+   */
+  GLdouble gapL, gapR;
+
+  assert( TransLeq( u, v ) && TransLeq( v, w ));
+  
+  gapL = v->t - u->t;
+  gapR = w->t - v->t;
+
+  if( gapL + gapR > 0 ) {
+    if( gapL < gapR ) {
+      return (v->s - u->s) + (u->s - w->s) * (gapL / (gapL + gapR));
+    } else {
+      return (v->s - w->s) + (w->s - u->s) * (gapR / (gapL + gapR));
+    }
+  }
+  /* vertical line */
+  return 0;
+}
+
+GLdouble __gl_transSign( GLUvertex *u, GLUvertex *v, GLUvertex *w )
+{
+  /* Returns a number whose sign matches TransEval(u,v,w) but which
+   * is cheaper to evaluate.  Returns > 0, == 0 , or < 0
+   * as v is above, on, or below the edge uw.
+   */
+  GLdouble gapL, gapR;
+
+  assert( TransLeq( u, v ) && TransLeq( v, w ));
+  
+  gapL = v->t - u->t;
+  gapR = w->t - v->t;
+
+  if( gapL + gapR > 0 ) {
+    return (v->s - w->s) * gapL + (v->s - u->s) * gapR;
+  }
+  /* vertical line */
+  return 0;
+}
+
+
+int __gl_vertCCW( GLUvertex *u, GLUvertex *v, GLUvertex *w )
+{
+  /* For almost-degenerate situations, the results are not reliable.
+   * Unless the floating-point arithmetic can be performed without
+   * rounding errors, *any* implementation will give incorrect results
+   * on some degenerate inputs, so the client must have some way to
+   * handle this situation.
+   */
+  return (u->s*(v->t - w->t) + v->s*(w->t - u->t) + w->s*(u->t - v->t)) >= 0;
+}
+
+/* Given parameters a,x,b,y returns the value (b*x+a*y)/(a+b),
+ * or (x+y)/2 if a==b==0.  It requires that a,b >= 0, and enforces
+ * this in the rare case that one argument is slightly negative.
+ * The implementation is extremely stable numerically.
+ * In particular it guarantees that the result r satisfies
+ * MIN(x,y) <= r <= MAX(x,y), and the results are very accurate
+ * even when a and b differ greatly in magnitude.
+ */
+#define RealInterpolate(a,x,b,y)			\
+  (a = (a < 0) ? 0 : a, b = (b < 0) ? 0 : b,		\
+  ((a <= b) ? ((b == 0) ? ((x+y) / 2)			\
+                        : (x + (y-x) * (a/(a+b))))	\
+            : (y + (x-y) * (b/(a+b)))))
+
+#ifndef FOR_TRITE_TEST_PROGRAM
+#define Interpolate(a,x,b,y)	RealInterpolate(a,x,b,y)
+#else
+
+/* Claim: the ONLY property the sweep algorithm relies on is that
+ * MIN(x,y) <= r <= MAX(x,y).  This is a nasty way to test that.
+ */
+#include <stdlib.h>
+extern int RandomInterpolate;
+
+GLdouble Interpolate( GLdouble a, GLdouble x, GLdouble b, GLdouble y)
+{
+printf("*********************%d\n",RandomInterpolate);
+  if( RandomInterpolate ) {
+    a = 1.2 * drand48() - 0.1;
+    a = (a < 0) ? 0 : ((a > 1) ? 1 : a);
+    b = 1.0 - a;
+  }
+  return RealInterpolate(a,x,b,y);
+}
+
+#endif
+
+#define Swap(a,b)	if (1) { GLUvertex *t = a; a = b; b = t; } else
+
+void __gl_edgeIntersect( GLUvertex *o1, GLUvertex *d1,
+			 GLUvertex *o2, GLUvertex *d2,
+			 GLUvertex *v )
+/* Given edges (o1,d1) and (o2,d2), compute their point of intersection.
+ * The computed point is guaranteed to lie in the intersection of the
+ * bounding rectangles defined by each edge.
+ */
+{
+  GLdouble z1, z2;
+
+  /* This is certainly not the most efficient way to find the intersection
+   * of two line segments, but it is very numerically stable.
+   *
+   * Strategy: find the two middle vertices in the VertLeq ordering,
+   * and interpolate the intersection s-value from these.  Then repeat
+   * using the TransLeq ordering to find the intersection t-value.
+   */
+
+  if( ! VertLeq( o1, d1 )) { Swap( o1, d1 ); }
+  if( ! VertLeq( o2, d2 )) { Swap( o2, d2 ); }
+  if( ! VertLeq( o1, o2 )) { Swap( o1, o2 ); Swap( d1, d2 ); }
+
+  if( ! VertLeq( o2, d1 )) {
+    /* Technically, no intersection -- do our best */
+    v->s = (o2->s + d1->s) / 2;
+  } else if( VertLeq( d1, d2 )) {
+    /* Interpolate between o2 and d1 */
+    z1 = EdgeEval( o1, o2, d1 );
+    z2 = EdgeEval( o2, d1, d2 );
+    if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
+    v->s = Interpolate( z1, o2->s, z2, d1->s );
+  } else {
+    /* Interpolate between o2 and d2 */
+    z1 = EdgeSign( o1, o2, d1 );
+    z2 = -EdgeSign( o1, d2, d1 );
+    if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
+    v->s = Interpolate( z1, o2->s, z2, d2->s );
+  }
+
+  /* Now repeat the process for t */
+
+  if( ! TransLeq( o1, d1 )) { Swap( o1, d1 ); }
+  if( ! TransLeq( o2, d2 )) { Swap( o2, d2 ); }
+  if( ! TransLeq( o1, o2 )) { Swap( o1, o2 ); Swap( d1, d2 ); }
+
+  if( ! TransLeq( o2, d1 )) {
+    /* Technically, no intersection -- do our best */
+    v->t = (o2->t + d1->t) / 2;
+  } else if( TransLeq( d1, d2 )) {
+    /* Interpolate between o2 and d1 */
+    z1 = TransEval( o1, o2, d1 );
+    z2 = TransEval( o2, d1, d2 );
+    if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
+    v->t = Interpolate( z1, o2->t, z2, d1->t );
+  } else {
+    /* Interpolate between o2 and d2 */
+    z1 = TransSign( o1, o2, d1 );
+    z2 = -TransSign( o1, d2, d1 );
+    if( z1+z2 < 0 ) { z1 = -z1; z2 = -z2; }
+    v->t = Interpolate( z1, o2->t, z2, d2->t );
+  }
+}