--- ray/src/common/face.c	1993/05/14 13:42:53	2.3
+++ ray/src/common/face.c	2003/03/21 18:48:46	2.10
@@ -1,15 +1,12 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char RCSid[] = "$Id: face.c,v 2.10 2003/03/21 18:48:46 greg Exp $";
 #endif
-
 /*
  *  face.c - routines dealing with polygonal faces.
- *
- *     8/30/85
  */
 
+#include "copyright.h"
+
 #include  "standard.h"
 
 #include  "object.h"
@@ -28,9 +25,9 @@ static char SCCSid[] = "$SunId$ LBL";
  */
 
 #ifdef  SMLFLT
-#define  VERTEPS	1e-2		/* allowed vertex error */
+#define  VERTEPS	1e-3		/* allowed vertex error */
 #else
-#define  VERTEPS	1e-4		/* allowed vertex error */
+#define  VERTEPS	1e-5		/* allowed vertex error */
 #endif
 
 
@@ -39,7 +36,7 @@ getface(o)			/* get arguments for a face */
 OBJREC  *o;
 {
 	double  d1;
-	int  badvert;
+	int  smalloff, badvert;
 	FVECT  v1, v2, v3;
 	register FACE  *f;
 	register int  i;
@@ -58,10 +55,15 @@ OBJREC  *o;
 
 	f->va = o->oargs.farg;
 	f->nv = o->oargs.nfargs / 3;
+						/* check for last==first */
+	if (dist2(VERTEX(f,0),VERTEX(f,f->nv-1)) <= FTINY*FTINY)
+		f->nv--;
 						/* compute area and normal */
 	f->norm[0] = f->norm[1] = f->norm[2] = 0.0;
-	v1[0] = v1[1] = v1[2] = 0.0;
-	for (i = 1; i < f->nv; i++) {
+	v1[0] = VERTEX(f,1)[0] - VERTEX(f,0)[0];
+	v1[1] = VERTEX(f,1)[1] - VERTEX(f,0)[1];
+	v1[2] = VERTEX(f,1)[2] - VERTEX(f,0)[2];
+	for (i = 2; i < f->nv; i++) {
 		v2[0] = VERTEX(f,i)[0] - VERTEX(f,0)[0];
 		v2[1] = VERTEX(f,i)[1] - VERTEX(f,0)[1];
 		v2[2] = VERTEX(f,i)[2] - VERTEX(f,0)[2];
@@ -82,13 +84,17 @@ OBJREC  *o;
 						/* compute offset */
 	badvert = 0;
 	f->offset = DOT(f->norm, VERTEX(f,0));
+	smalloff = fabs(f->offset) <= VERTEPS;
 	for (i = 1; i < f->nv; i++) {
 		d1 = DOT(f->norm, VERTEX(f,i));
-		badvert += fabs(d1 - f->offset/i) > VERTEPS;
+		if (smalloff)
+			badvert += fabs(d1 - f->offset/i) > VERTEPS;
+		else
+			badvert += fabs(1.0 - d1*i/f->offset) > VERTEPS;
 		f->offset += d1;
 	}
 	f->offset /= (double)f->nv;
-	if (badvert)
+	if (f->nv > 3 && badvert)
 		objerror(o, WARNING, "non-planar vertex");
 						/* find axis */
 	f->ax = fabs(f->norm[0]) > fabs(f->norm[1]) ? 0 : 1;
@@ -99,6 +105,7 @@ OBJREC  *o;
 }
 
 
+void
 freeface(o)			/* free memory associated with face */
 OBJREC  *o;
 {
@@ -109,12 +116,14 @@ OBJREC  *o;
 }
 
 
+int
 inface(p, f)			/* determine if point is in face */
 FVECT  p;
 FACE  *f;
 {
 	int  ncross, n;
 	double  x, y;
+	int  tst;
 	register int  xi, yi;
 	register FLOAT  *p0, *p1;
 
@@ -128,13 +137,15 @@ FACE  *f;
 	ncross = 0;
 					/* positive x axis cross test */
 	while (n--) {
-		if ((p0[yi] > y) ^ (p1[yi] > y))
-			if (p0[xi] > x && p1[xi] > x)
+		if ((p0[yi] > y) ^ (p1[yi] > y)) {
+			tst = (p0[xi] > x) + (p1[xi] > x);
+			if (tst == 2)
 				ncross++;
-			else if (p0[xi] > x || p1[xi] > x)
+			else if (tst)
 				ncross += (p1[yi] > p0[yi]) ^
 						((p0[yi]-y)*(p1[xi]-x) >
 						(p0[xi]-x)*(p1[yi]-y));
+		}
 		p0 = p1;
 		p1 += 3;
 	}