src/rt/text.c

/* Copyright (c) 1998 Silicon Graphics, Inc. */

#ifndef lint
static char SCCSid[] = "$SunId$ SGI";
#endif

/*
 *  text.c - functions for text patterns and mixtures.
 */

#include  "ray.h"

#include  "otypes.h"

#include  "font.h"

/*
 *      A text pattern is specified as the text (a file or line),
 *  the upper left anchor point, the right motion vector, the down
 *  motion vector, and the foreground and background brightness.
 *  For a file, the description is as follows:
 *
 *      modifier brighttext id
 *      2 fontfile textfile
 *      0
 *      11+
 *              Ax Ay Az
 *              Rx Ry Rz
 *              Dx Dy Dz
 *              foreground background
 *              [spacing]
 *
 *  For a single line, we use:
 *
 *      modifier brighttext id
 *      N+2 fontfile . This is a line with N words...
 *      0
 *      11+
 *              Ax Ay Az
 *              Rx Ry Rz
 *              Dx Dy Dz
 *              foreground background
 *              [spacing]
 *
 *  Colortext is identical, except colors are given rather than
 *  brightnesses.
 *
 *  Mixtext has foreground and background modifiers:
 *
 *      modifier mixtext id
 *      4+ foremod backmod fontfile text..
 *      0
 *      9+
 *              Ax Ay Az
 *              Rx Ry Rz
 *              Dx Dy Dz
 *              [spacing]
 */

#define  fndx(m)        ((m)->otype==MIX_TEXT ? 2 : 0)
#define  tndx(m)        ((m)->otype==MIX_TEXT ? 3 : 1)
#define  sndx(m)        ((m)->otype==PAT_BTEXT ? 11 : \
                                (m)->otype==PAT_CTEXT ? 15 : 9)

typedef struct tline {
        struct tline  *next;            /* pointer to next line */
        short  *spc;                    /* character spacing */
        int  width;                     /* total line width */
                                        /* followed by the string */
}  TLINE;

#define  TLSTR(l)       ((char *)((l)+1))

typedef struct {
        FVECT  right, down;             /* right and down unit vectors */
        FONT  *f;                       /* our font */
        TLINE  tl;                      /* line list */
}  TEXT;

extern char  *getlibpath();

extern char  *fgetword();

TEXT  *gettext();

TLINE  *tlalloc();


do_text(m, r)
register OBJREC  *m;
RAY  *r;
{
        FVECT  v;
        int  foreground;
                                /* get transformed position */
        if (r->rox != NULL)
                multp3(v, r->rop, r->rox->b.xfm);
        else
                VCOPY(v, r->rop);
                                /* check if we are within a text glyph */
        foreground = intext(v, m);
                                /* modify */
        if (m->otype == MIX_TEXT) {
                OBJECT  omod;
                char  *modname = m->oargs.sarg[foreground ? 0 : 1];
                if (!strcmp(modname, VOIDID))
                        omod = OVOID;
                else if ((omod = lastmod(objndx(m), modname)) == OVOID) {
                        sprintf(errmsg, "undefined modifier \"%s\"", modname);
                        objerror(m, USER, errmsg);
                }
                if (rayshade(r, omod)) {
                        if (m->omod != OVOID)
                                objerror(m, USER, "inappropriate modifier");
                        return(1);
                }
        } else if (m->otype == PAT_BTEXT) {
                if (foreground)
                        scalecolor(r->pcol, m->oargs.farg[9]);
                else
                        scalecolor(r->pcol, m->oargs.farg[10]);
        } else { /* PAT_CTEXT */
                COLOR  cval;
                if (foreground)
                        setcolor(cval, m->oargs.farg[9],
                                        m->oargs.farg[10],
                                        m->oargs.farg[11]);
                else
                        setcolor(cval, m->oargs.farg[12],
                                        m->oargs.farg[13],
                                        m->oargs.farg[14]);
                multcolor(r->pcol, cval);
        }
        return(0);
}


TLINE *
tlalloc(s)                      /* allocate and assign text line */
char  *s;
{
        extern char  *strcpy();
        register int  siz;
        register TLINE  *tl;

        siz = strlen(s) + 1;
        if ((tl=(TLINE *)malloc(sizeof(TLINE)+siz)) == NULL ||
                        (tl->spc=(short *)malloc(siz*sizeof(short))) == NULL)
                error(SYSTEM, "out of memory in tlalloc");
        tl->next = NULL;
        strcpy(TLSTR(tl), s);
        return(tl);
}


TEXT *
gettext(tm)                     /* get text structure for material */
register OBJREC  *tm;
{
#define  R      (tm->oargs.farg+3)
#define  D      (tm->oargs.farg+6)
        extern char  *strcpy();
        FVECT  DxR;
        double  d;
        FILE  *fp;
        char  linbuf[512];
        TEXT  *t;
        register int  i;
        register TLINE  *tlp;
        register char  *s;

        if ((t = (TEXT *)tm->os) != NULL)
                return(t);
                                                /* check arguments */
        if (tm->oargs.nsargs - tndx(tm) < 1 || tm->oargs.nfargs < sndx(tm))
                objerror(tm, USER, "bad # arguments");
        if ((t = (TEXT *)malloc(sizeof(TEXT))) == NULL)
                error(SYSTEM, "out of memory in gettext");
                                                /* compute vectors */
        fcross(DxR, D, R);
        fcross(t->right, DxR, D);
        d = DOT(t->right,t->right);
        if (d <= FTINY*FTINY*FTINY*FTINY)
                objerror(tm, USER, "illegal motion vector");
        d = DOT(D,D)/d;
        for (i = 0; i < 3; i++)
                t->right[i] *= d;
        fcross(t->down, R, DxR);
        d = DOT(R,R)/DOT(t->down,t->down);
        for (i = 0; i < 3; i++)
                t->down[i] *= d;
                                                /* get text */
        tlp = &t->tl;
        if (tm->oargs.nsargs - tndx(tm) > 1) {  /* single line */
                s = linbuf;
                for (i = tndx(tm)+1; i < tm->oargs.nsargs; i++) {
                        strcpy(s, tm->oargs.sarg[i]);
                        s += strlen(s);
                        *s++ = ' ';
                }
                *--s = '\0';
                tlp->next = tlalloc(linbuf);
                tlp = tlp->next;
        } else {                                /* text file */
                if ((s = getpath(tm->oargs.sarg[tndx(tm)],
                                getlibpath(), R_OK)) == NULL) {
                        sprintf(errmsg, "cannot find text file \"%s\"",
                                        tm->oargs.sarg[tndx(tm)]);
                        error(USER, errmsg);
                }
                if ((fp = fopen(s, "r")) == NULL) {
                        sprintf(errmsg, "cannot open text file \"%s\"", s);
                        error(SYSTEM, errmsg);
                }
                while (fgets(linbuf, sizeof(linbuf), fp) != NULL) {
                        s = linbuf + strlen(linbuf) - 1;
                        if (*s == '\n')
                                *s = '\0';
                        tlp->next = tlalloc(linbuf);
                        tlp = tlp->next;
                }
                fclose(fp);
        }
        tlp->next = NULL;
                                                /* get the font */
        t->f = getfont(tm->oargs.sarg[fndx(tm)]);
                                                /* compute character spacing */
        i = sndx(tm);
        d = i < tm->oargs.nfargs ? tm->oargs.farg[i] : 0.0;
        i = d * 255.0;
        t->tl.width = 0;
        for (tlp = t->tl.next; tlp != NULL; tlp = tlp->next) {
                if (i < 0)
                        tlp->width = squeeztext(tlp->spc, TLSTR(tlp), t->f, -i);
                else if (i > 0)
                        tlp->width = proptext(tlp->spc, TLSTR(tlp), t->f, i, 3);
                else
                        tlp->width = uniftext(tlp->spc, TLSTR(tlp), t->f);
                if (tlp->width > t->tl.width)
                        t->tl.width = tlp->width;
        }
                                                /* we're done */
        tm->os = (char *)t;
        return(t);
#undef  R
#undef  D
}


freetext(m)                     /* free text structures associated with m */
OBJREC  *m;
{
        register TEXT  *tp;
        register TLINE  *tlp;

        tp = (TEXT *)m->os;
        if (tp == NULL)
                return;
        while ((tlp = tp->tl.next) != NULL) {
                tp->tl.next = tlp->next;
                free((char *)tlp->spc);
                free((char *)tlp);
        }
        free((char *)tp);
        m->os = NULL;
}


intext(p, m)                    /* check to see if p is in text glyph */
FVECT  p;
OBJREC  *m;
{
        register TEXT  *tp;
        register TLINE  *tlp;
        FVECT  v;
        double  y, x;
        register int  i, h;
                                /* first, compute position in text */
        tp = gettext(m);
        v[0] = p[0] - m->oargs.farg[0];
        v[1] = p[1] - m->oargs.farg[1];
        v[2] = p[2] - m->oargs.farg[2];
        x = DOT(v, tp->right);
        i = sndx(m);
        if (i < m->oargs.nfargs)
                x *= tp->f->mwidth + 255.*fabs(m->oargs.farg[i]);
        else
                x *= 255.;
        h = x;
        i = y = DOT(v, tp->down);
        if (x < 0.0 || y < 0.0)
                return(0);
        x -= (double)h;
        y = ((i+1) - y)*255.;
                                /* find the line position */
        for (tlp = tp->tl.next; tlp != NULL; tlp = tlp->next)
                if (--i < 0)
                        break;
        if (tlp == NULL || h >= tlp->width)
                return(0);
        for (i = 0; (h -= tlp->spc[i]) >= 0; i++)
                if (h < 255 && inglyph(h+x, y,
                                tp->f->fg[TLSTR(tlp)[i]&0xff]))
                        return(1);
        return(0);
}


inglyph(x, y, gl)               /* (x,y) within font glyph gl? */
double  x, y;           /* real coordinates in range [0,255) */
register GLYPH  *gl;
{
        int  n, ncross;
        int  xlb, ylb;
        int  tv;
        register GORD  *p0, *p1;

        if (gl == NULL)
                return(0);
        xlb = x;
        ylb = y;
        if (gl->left > xlb || gl->right <= xlb ||       /* check extent */
                        gl->bottom > ylb || gl->top <= ylb)
                return(0);
        xlb = xlb<<1 | 1;               /* add 1/2 to test points... */
        ylb = ylb<<1 | 1;               /* ...so no equal comparisons */
        n = gl->nverts;                 /* get # of vertices */
        p0 = gvlist(gl) + 2*(n-1);      /* connect last to first */
        p1 = gvlist(gl);
        ncross = 0;
                                        /* positive x axis cross test */
        while (n--) {
                if ((p0[1]<<1 > ylb) ^ (p1[1]<<1 > ylb)) {
                        tv = p0[0]<<1 > xlb | (p1[0]<<1 > xlb) << 1;
                        if (tv == 03)
                                ncross++;
                        else if (tv)
                                ncross += (p1[1] > p0[1]) ^
                                                ((p0[1]-y)*(p1[0]-x) >
                                                (p0[0]-x)*(p1[1]-y));
                }
                p0 = p1;
                p1 += 2;
        }
        return(ncross & 01);
}
Revision:	2.19
Committed:	Thu May 20 13:51:19 1999 UTC (24 years, 11 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 2.18:	+1 -1 lines
Log Message:	decreased epsilon for check of zero motion vector
#	User	Rev	Content
1	gwlarson	2.18	/* Copyright (c) 1998 Silicon Graphics, Inc. */
2	greg	1.1
3			#ifndef lint
4	gwlarson	2.18	static char SCCSid[] = "$SunId$ SGI";
5	greg	1.1	#endif
6
7			/*
8			* text.c - functions for text patterns and mixtures.
9			*/
10
11			#include "ray.h"
12
13			#include "otypes.h"
14
15	greg	2.2	#include "font.h"
16
17	greg	1.1	/*
18			* A text pattern is specified as the text (a file or line),
19			* the upper left anchor point, the right motion vector, the down
20			* motion vector, and the foreground and background brightness.
21			* For a file, the description is as follows:
22			*
23			* modifier brighttext id
24			* 2 fontfile textfile
25			* 0
26	greg	2.4	* 11+
27	greg	1.1	* Ax Ay Az
28			* Rx Ry Rz
29			* Dx Dy Dz
30			* foreground background
31	greg	2.4	* [spacing]
32	greg	1.1	*
33			* For a single line, we use:
34			*
35			* modifier brighttext id
36			* N+2 fontfile . This is a line with N words...
37			* 0
38	greg	2.4	* 11+
39	greg	1.1	* Ax Ay Az
40			* Rx Ry Rz
41			* Dx Dy Dz
42			* foreground background
43	greg	2.4	* [spacing]
44	greg	1.1	*
45			* Colortext is identical, except colors are given rather than
46	greg	2.15	* brightnesses.
47	greg	1.1	*
48	greg	2.15	* Mixtext has foreground and background modifiers:
49			*
50	greg	1.1	* modifier mixtext id
51			* 4+ foremod backmod fontfile text..
52			* 0
53	greg	2.4	* 9+
54	greg	1.1	* Ax Ay Az
55			* Rx Ry Rz
56			* Dx Dy Dz
57	greg	2.4	* [spacing]
58	greg	1.1	*/
59
60			#define fndx(m) ((m)->otype==MIX_TEXT ? 2 : 0)
61			#define tndx(m) ((m)->otype==MIX_TEXT ? 3 : 1)
62	greg	2.4	#define sndx(m) ((m)->otype==PAT_BTEXT ? 11 : \
63			(m)->otype==PAT_CTEXT ? 15 : 9)
64	greg	1.1
65	greg	1.8	typedef struct tline {
66			struct tline next; / pointer to next line */
67	greg	2.4	short spc; / character spacing */
68			int width; /* total line width */
69	greg	1.8	/* followed by the string */
70			} TLINE;
71
72	greg	1.9	#define TLSTR(l) ((char *)((l)+1))
73	greg	1.8
74	greg	1.7	typedef struct {
75			FVECT right, down; /* right and down unit vectors */
76			FONT f; / our font */
77	greg	1.8	TLINE tl; /* line list */
78	greg	1.7	} TEXT;
79
80	greg	2.13	extern char *getlibpath();
81	greg	2.3
82	greg	1.6	extern char *fgetword();
83
84	greg	1.7	TEXT *gettext();
85	greg	1.1
86	greg	1.8	TLINE *tlalloc();
87
88	greg	1.1
89	greg	2.16	do_text(m, r)
90	greg	1.1	register OBJREC *m;
91			RAY *r;
92			{
93	greg	1.10	FVECT v;
94	greg	1.1	int foreground;
95	greg	1.7	/* get transformed position */
96	greg	1.4	if (r->rox != NULL)
97			multp3(v, r->rop, r->rox->b.xfm);
98			else
99			VCOPY(v, r->rop);
100	greg	1.7	/* check if we are within a text glyph */
101			foreground = intext(v, m);
102	greg	1.1	/* modify */
103			if (m->otype == MIX_TEXT) {
104			OBJECT omod;
105			char *modname = m->oargs.sarg[foreground ? 0 : 1];
106			if (!strcmp(modname, VOIDID))
107			omod = OVOID;
108	gwlarson	2.18	else if ((omod = lastmod(objndx(m), modname)) == OVOID) {
109	greg	1.1	sprintf(errmsg, "undefined modifier \"%s\"", modname);
110			objerror(m, USER, errmsg);
111			}
112	greg	2.12	if (rayshade(r, omod)) {
113			if (m->omod != OVOID)
114			objerror(m, USER, "inappropriate modifier");
115			return(1);
116			}
117	greg	2.15	} else if (m->otype == PAT_BTEXT) {
118	greg	1.1	if (foreground)
119	greg	1.7	scalecolor(r->pcol, m->oargs.farg[9]);
120	greg	1.1	else
121	greg	1.7	scalecolor(r->pcol, m->oargs.farg[10]);
122	greg	1.1	} else { /* PAT_CTEXT */
123			COLOR cval;
124			if (foreground)
125	greg	1.7	setcolor(cval, m->oargs.farg[9],
126			m->oargs.farg[10],
127			m->oargs.farg[11]);
128	greg	1.1	else
129	greg	1.7	setcolor(cval, m->oargs.farg[12],
130			m->oargs.farg[13],
131			m->oargs.farg[14]);
132	greg	1.1	multcolor(r->pcol, cval);
133			}
134	greg	2.12	return(0);
135	greg	1.1	}
136
137
138	greg	1.8	TLINE *
139			tlalloc(s) /* allocate and assign text line */
140			char *s;
141			{
142			extern char *strcpy();
143	greg	2.4	register int siz;
144	greg	1.8	register TLINE *tl;
145
146	greg	2.4	siz = strlen(s) + 1;
147			if ((tl=(TLINE *)malloc(sizeof(TLINE)+siz)) == NULL \|\|
148			(tl->spc=(short )malloc(sizsizeof(short))) == NULL)
149	greg	1.8	error(SYSTEM, "out of memory in tlalloc");
150			tl->next = NULL;
151			strcpy(TLSTR(tl), s);
152			return(tl);
153			}
154
155
156	greg	1.7	TEXT *
157			gettext(tm) /* get text structure for material */
158	greg	1.1	register OBJREC *tm;
159			{
160	greg	1.7	#define R (tm->oargs.farg+3)
161			#define D (tm->oargs.farg+6)
162	greg	2.11	extern char *strcpy();
163	greg	1.7	FVECT DxR;
164			double d;
165	greg	1.1	FILE *fp;
166			char linbuf[512];
167	greg	1.8	TEXT *t;
168	greg	1.1	register int i;
169	greg	1.8	register TLINE *tlp;
170	greg	1.1	register char *s;
171
172	greg	1.7	if ((t = (TEXT *)tm->os) != NULL)
173			return(t);
174			/* check arguments */
175	greg	2.4	if (tm->oargs.nsargs - tndx(tm) < 1 \|\| tm->oargs.nfargs < sndx(tm))
176	greg	1.7	objerror(tm, USER, "bad # arguments");
177			if ((t = (TEXT *)malloc(sizeof(TEXT))) == NULL)
178	greg	2.10	error(SYSTEM, "out of memory in gettext");
179	greg	1.7	/* compute vectors */
180			fcross(DxR, D, R);
181			fcross(t->right, DxR, D);
182	gregl	2.17	d = DOT(t->right,t->right);
183	gwlarson	2.19	if (d <= FTINYFTINYFTINY*FTINY)
184	gregl	2.17	objerror(tm, USER, "illegal motion vector");
185			d = DOT(D,D)/d;
186	greg	1.7	for (i = 0; i < 3; i++)
187			t->right[i] *= d;
188			fcross(t->down, R, DxR);
189	greg	1.9	d = DOT(R,R)/DOT(t->down,t->down);
190	greg	1.7	for (i = 0; i < 3; i++)
191			t->down[i] *= d;
192			/* get text */
193	greg	1.8	tlp = &t->tl;
194	greg	1.7	if (tm->oargs.nsargs - tndx(tm) > 1) { /* single line */
195			s = linbuf;
196			for (i = tndx(tm)+1; i < tm->oargs.nsargs; i++) {
197			strcpy(s, tm->oargs.sarg[i]);
198			s += strlen(s);
199			*s++ = ' ';
200	greg	1.1	}
201	greg	1.7	*--s = '\0';
202	greg	1.8	tlp->next = tlalloc(linbuf);
203			tlp = tlp->next;
204	greg	1.7	} else { /* text file */
205			if ((s = getpath(tm->oargs.sarg[tndx(tm)],
206	greg	2.13	getlibpath(), R_OK)) == NULL) {
207	greg	1.7	sprintf(errmsg, "cannot find text file \"%s\"",
208			tm->oargs.sarg[tndx(tm)]);
209			error(USER, errmsg);
210			}
211			if ((fp = fopen(s, "r")) == NULL) {
212	greg	2.4	sprintf(errmsg, "cannot open text file \"%s\"", s);
213	greg	1.7	error(SYSTEM, errmsg);
214			}
215	greg	1.8	while (fgets(linbuf, sizeof(linbuf), fp) != NULL) {
216	greg	1.7	s = linbuf + strlen(linbuf) - 1;
217			if (*s == '\n')
218			*s = '\0';
219	greg	1.8	tlp->next = tlalloc(linbuf);
220			tlp = tlp->next;
221	greg	1.7	}
222			fclose(fp);
223	greg	1.1	}
224	greg	1.8	tlp->next = NULL;
225	greg	1.7	/* get the font */
226			t->f = getfont(tm->oargs.sarg[fndx(tm)]);
227	greg	2.4	/* compute character spacing */
228			i = sndx(tm);
229			d = i < tm->oargs.nfargs ? tm->oargs.farg[i] : 0.0;
230	greg	2.14	i = d * 255.0;
231	greg	2.6	t->tl.width = 0;
232	greg	2.4	for (tlp = t->tl.next; tlp != NULL; tlp = tlp->next) {
233			if (i < 0)
234			tlp->width = squeeztext(tlp->spc, TLSTR(tlp), t->f, -i);
235			else if (i > 0)
236			tlp->width = proptext(tlp->spc, TLSTR(tlp), t->f, i, 3);
237			else
238			tlp->width = uniftext(tlp->spc, TLSTR(tlp), t->f);
239	greg	2.6	if (tlp->width > t->tl.width)
240			t->tl.width = tlp->width;
241	greg	2.4	}
242	greg	1.7	/* we're done */
243			tm->os = (char *)t;
244			return(t);
245			#undef R
246			#undef D
247	greg	1.1	}
248
249
250	greg	1.7	freetext(m) /* free text structures associated with m */
251			OBJREC *m;
252			{
253	greg	2.9	register TEXT *tp;
254			register TLINE *tlp;
255	greg	1.7
256			tp = (TEXT *)m->os;
257			if (tp == NULL)
258			return;
259	greg	2.9	while ((tlp = tp->tl.next) != NULL) {
260			tp->tl.next = tlp->next;
261	greg	2.4	free((char *)tlp->spc);
262	greg	1.9	free((char *)tlp);
263	greg	2.4	}
264	greg	1.7	free((char *)tp);
265			m->os = NULL;
266			}
267
268
269			intext(p, m) /* check to see if p is in text glyph */
270			FVECT p;
271	greg	1.8	OBJREC *m;
272	greg	1.7	{
273			register TEXT *tp;
274	greg	1.8	register TLINE *tlp;
275	greg	1.10	FVECT v;
276			double y, x;
277	greg	2.4	register int i, h;
278	greg	1.7	/* first, compute position in text */
279	greg	1.9	tp = gettext(m);
280	greg	1.7	v[0] = p[0] - m->oargs.farg[0];
281			v[1] = p[1] - m->oargs.farg[1];
282			v[2] = p[2] - m->oargs.farg[2];
283	greg	2.6	x = DOT(v, tp->right);
284			i = sndx(m);
285			if (i < m->oargs.nfargs)
286	greg	2.14	x = tp->f->mwidth + 255.fabs(m->oargs.farg[i]);
287	greg	2.6	else
288	greg	2.14	x *= 255.;
289	greg	2.6	h = x;
290	greg	2.4	i = y = DOT(v, tp->down);
291	greg	1.7	if (x < 0.0 \|\| y < 0.0)
292			return(0);
293	greg	2.4	x -= (double)h;
294	greg	2.14	y = ((i+1) - y)*255.;
295	greg	2.4	/* find the line position */
296	greg	1.8	for (tlp = tp->tl.next; tlp != NULL; tlp = tlp->next)
297	greg	2.4	if (--i < 0)
298	greg	1.8	break;
299	greg	2.4	if (tlp == NULL \|\| h >= tlp->width)
300	greg	1.7	return(0);
301	greg	2.4	for (i = 0; (h -= tlp->spc[i]) >= 0; i++)
302	greg	2.14	if (h < 255 && inglyph(h+x, y,
303	greg	2.4	tp->f->fg[TLSTR(tlp)[i]&0xff]))
304			return(1);
305			return(0);
306	greg	1.7	}
307
308
309	greg	1.1	inglyph(x, y, gl) /* (x,y) within font glyph gl? */
310	greg	2.14	double x, y; /* real coordinates in range [0,255) */
311	greg	2.3	register GLYPH *gl;
312	greg	1.1	{
313			int n, ncross;
314	greg	2.5	int xlb, ylb;
315			int tv;
316	greg	2.2	register GORD p0, p1;
317	greg	1.1
318	greg	1.7	if (gl == NULL)
319	greg	1.1	return(0);
320	greg	2.5	xlb = x;
321			ylb = y;
322			if (gl->left > xlb \|\| gl->right <= xlb \|\| /* check extent */
323			gl->bottom > ylb \|\| gl->top <= ylb)
324			return(0);
325			xlb = xlb<<1 \| 1; /* add 1/2 to test points... */
326			ylb = ylb<<1 \| 1; /* ...so no equal comparisons */
327	greg	2.2	n = gl->nverts; /* get # of vertices */
328			p0 = gvlist(gl) + 2(n-1); / connect last to first */
329			p1 = gvlist(gl);
330	greg	1.1	ncross = 0;
331			/* positive x axis cross test */
332			while (n--) {
333	greg	2.5	if ((p0[1]<<1 > ylb) ^ (p1[1]<<1 > ylb)) {
334			tv = p0[0]<<1 > xlb \| (p1[0]<<1 > xlb) << 1;
335			if (tv == 03)
336	greg	1.1	ncross++;
337	greg	2.5	else if (tv)
338	greg	1.1	ncross += (p1[1] > p0[1]) ^
339			((p0[1]-y)*(p1[0]-x) >
340			(p0[0]-x)*(p1[1]-y));
341	greg	2.5	}
342	greg	1.1	p0 = p1;
343			p1 += 2;
344			}
345			return(ncross & 01);
346			}