--- ray/src/cv/mgf2meta.c	1995/04/11 13:32:47	2.3
+++ ray/src/cv/mgf2meta.c	2003/02/22 02:07:23	2.6
@@ -1,24 +1,25 @@
-/* Copyright (c) 1995 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: mgf2meta.c,v 2.6 2003/02/22 02:07:23 greg Exp $";
 #endif
-
 /*
  * Convert MGF (Materials and Geometry Format) to Metafile 2-d graphics
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <math.h>
+#include "random.h"
 #include "mgflib/parser.h"
 
-#define	MX(v)	(int)(((1<<14)-1)*(v)[(proj_axis+1)%3])
-#define	MY(v)	(int)(((1<<14)-1)*(v)[(proj_axis+2)%3])
+#define MSIZE	((1<<14)-1)
+#define	MX(v)	(int)(MSIZE*(v)[(proj_axis+1)%3])
+#define	MY(v)	(int)(MSIZE*(v)[(proj_axis+2)%3])
 
 int	r_face();
 int	proj_axis;
 double	limit[3][2];
 int	layer;
+long	rthresh = 1;
 
 extern int	mg_nqcdivs;
 
@@ -36,6 +37,12 @@ char	*argv[];
 	mg_nqcdivs = 3;		/* reduce object subdivision */
 	mg_init();		/* initialize the parser */
 					/* get arguments */
+	if (argc > 9 && !strcmp(argv[1], "-t")) {
+		rthresh = atof(argv[2])*MSIZE + 0.5;
+		rthresh *= rthresh;
+		argv += 2;
+		argc -= 2;
+	}
 	if (argc < 8 || (proj_axis = argv[1][0]-'x') < 0 || proj_axis > 2)
 		goto userr;
 	limit[0][0] = atof(argv[2]); limit[0][1] = atof(argv[3]);
@@ -49,17 +56,14 @@ char	*argv[];
 		for (i = 8; i < argc; i++) {
 			if (mg_load(argv[i]) != MG_OK)
 				exit(1);
-			if (++layer >= 16) {
-				mendpage();
-				layer = 0;
-			}
+			newlayer();
 		}
 	mendpage();			/* print page */
 	mdone();			/* close output */
 	exit(0);
 userr:
-	fprintf(stderr, "Usage: %s {x|y|z} xmin xmax ymin ymax zmin zmax [file.mgf] ..\n",
-			argv[0]);
+	fputs("Usage: mgf2meta [-t thresh] {x|y|z} xmin xmax ymin ymax zmin zmax [file.mgf] ..\n",
+			stderr);
 	exit(1);
 }
 
@@ -73,7 +77,6 @@ char	**av;
 	register int	i, j;
 	register C_VERTEX	*cv;
 	FVECT	v1, v2, vo;
-	int	newline = 1;
 
 	if (ac < 4)
 		return(MG_EARGC);
@@ -91,10 +94,55 @@ char	**av;
 			v2[j] = (v2[j] - limit[j][0])/(limit[j][1]-limit[j][0]);
 		VCOPY(v1, vo);
 		VCOPY(vo, v2);
-		if (clip(v1, v2, bbmin, bbmax)) {
-			mline(MX(v1), MY(v1), layer/4, 0, layer%4);
-			mdraw(MX(v2), MY(v2));
-		}
+		if (clip(v1, v2, bbmin, bbmax))
+			doline(MX(v1), MY(v1), MX(v2), MY(v2));
 	}
 	return(MG_OK);
+}
+
+
+#define  HTBLSIZ	16381		/* prime hash table size */
+
+short	hshtab[HTBLSIZ][4];		/* done line segments */
+
+#define  hash(mx1,my1,mx2,my2)	((long)(mx1)<<15 ^ (long)(my1)<<10 ^ \
+					(long)(mx2)<<5 ^ (long)(my2))
+
+
+newlayer()				/* start a new layer */
+{
+#ifdef BSD
+	bzero((char *)hshtab, sizeof(hshtab));
+#else
+	(void)memset((char *)hshtab, 0, sizeof(hshtab));
+#endif
+	if (++layer >= 16) {
+		mendpage();
+		layer = 0;
+	}
+}
+
+
+int
+doline(v1x, v1y, v2x, v2y)		/* draw line conditionally */
+int	v1x, v1y, v2x, v2y;
+{
+	register int	h;
+
+	if (v1x > v2x || (v1x == v2x && v1y > v2y)) {	/* sort endpoints */
+		h=v1x; v1x=v2x; v2x=h;
+		h=v1y; v1y=v2y; v2y=h;
+	}
+	h = hash(v1x, v1y, v2x, v2y) % HTBLSIZ;
+	if (hshtab[h][0] == v1x && hshtab[h][1] == v1y &&
+			hshtab[h][2] == v2x && hshtab[h][3] == v2y)
+		return(0);
+	hshtab[h][0] = v1x; hshtab[h][1] = v1y;
+	hshtab[h][2] = v2x; hshtab[h][3] = v2y;
+	if ((long)(v2x-v1x)*(v2x-v1x) + (long)(v2y-v1y)*(v2y-v1y)
+			<= random() % rthresh)
+		return(0);
+	mline(v1x, v1y, layer/4, 0, layer%4);
+	mdraw(v2x, v2y);
+	return(1);
 }