src/hd/rhdisp3.c

#ifndef lint
static const char       RCSid[] = "$Id: rhdisp3.c,v 3.14 2003/07/21 22:30:18 schorsch Exp $";
#endif
/*
 * Holodeck beam support for display process
 */

#include "rholo.h"
#include "rhdisp.h"
#include "view.h"

struct cellist {
        GCOORD  *cl;
        int     n;
};


int
npixels(vp, hr, vr, hp, bi)     /* compute appropriate nrays to evaluate */
register VIEW   *vp;
int     hr, vr;
HOLO    *hp;
int     bi;
{
        VIEW    vrev;
        GCOORD  gc[2];
        FVECT   cp[4], ip[4], pf, pb;
        double  af, ab, sf2, sb2, dfb2, df2, db2, penalty;
        register int    i;
                                        /* special case */
        if (hr <= 0 | vr <= 0)
                return(0);
                                        /* compute cell corners in image */
        if (!hdbcoord(gc, hp, bi))
                error(CONSISTENCY, "bad beam index in npixels");
        hdcell(cp, hp, gc+1);           /* find cell on front image */
        for (i = 3; i--; )              /* compute front center */
                pf[i] = 0.5*(cp[0][i] + cp[2][i]);
        sf2 = 0.25*dist2(cp[0], cp[2]); /* compute half diagonal length */
        for (i = 0; i < 4; i++) {       /* compute visible quad */
                viewloc(ip[i], vp, cp[i]);
                if (ip[i][2] < 0.) {
                        af = 0;
                        goto getback;
                }
                ip[i][0] *= (double)hr; /* scale by resolution */
                ip[i][1] *= (double)vr;
        }
                                        /* compute front area */
        af = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
                (ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
        af += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
                (ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
        af *= af >= 0 ? 0.5 : -0.5;
getback:
        vrev = *vp;             /* compute reverse view */
        for (i = 0; i < 3; i++) {
                vrev.vdir[i] = -vp->vdir[i];
                vrev.vup[i] = -vp->vup[i];
                vrev.hvec[i] = -vp->hvec[i];
                vrev.vvec[i] = -vp->vvec[i];
        }
        hdcell(cp, hp, gc);             /* find cell on back image */
        for (i = 3; i--; )              /* compute rear center */
                pb[i] = 0.5*(cp[0][i] + cp[2][i]);
        sb2 = 0.25*dist2(cp[0], cp[2]); /* compute half diagonal length */
        for (i = 0; i < 4; i++) {       /* compute visible quad */
                viewloc(ip[i], &vrev, cp[i]);
                if (ip[i][2] < 0.) {
                        ab = 0;
                        goto finish;
                }
                ip[i][0] *= (double)hr; /* scale by resolution */
                ip[i][1] *= (double)vr;
        }
                                        /* compute back area */
        ab = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
                (ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
        ab += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
                (ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
        ab *= ab >= 0 ? 0.5 : -0.5;
finish:         /* compute penalty based on dist. sightline - viewpoint */
        df2 = dist2(vp->vp, pf);
        db2 = dist2(vp->vp, pb);
        dfb2 = dist2(pf, pb);
        penalty = dfb2 + df2 - db2;
        penalty = df2 - 0.25*penalty*penalty/dfb2;
        if (df2 > db2)  penalty /= df2 <= dfb2 ? sb2 : sb2*df2/dfb2;
        else            penalty /= db2 <= dfb2 ? sf2 : sf2*db2/dfb2;
        if (penalty < 1.) penalty = 1.;
                                        /* round off smaller non-zero area */
        if (ab <= FTINY || (af > FTINY && af <= ab))
                return((int)(af/penalty + 0.5));
        return((int)(ab/penalty + 0.5));
}


/*
 * The ray directions that define the pyramid in visit_cells() needn't
 * be normalized, but they must be given in clockwise order as seen
 * from the pyramid's apex (origin).
 * If no cell centers fall within the domain, the closest cell is visited.
 */
int
visit_cells(orig, pyrd, hp, vf, dp)     /* visit cells within a pyramid */
FVECT   orig, pyrd[4];          /* pyramid ray directions in clockwise order */
register HOLO   *hp;
int     (*vf)();
char    *dp;
{
        int     ncalls = 0, n = 0;
        int     inflags = 0;
        FVECT   gp, pn[4], lo, ld;
        double  po[4], lbeg, lend, d, t;
        GCOORD  gc, gc2[2];
        register int    i;
                                        /* figure out whose side we're on */
        hdgrid(gp, hp, orig);
        for (i = 0; i < 3; i++) {
                inflags |= (gp[i] > FTINY) << (i<<1);
                inflags |= (gp[i] < hp->grid[i]-FTINY) << (i<<1 | 1);
        }
                                        /* compute pyramid planes */
        for (i = 0; i < 4; i++) {
                fcross(pn[i], pyrd[i], pyrd[(i+1)&03]);
                po[i] = DOT(pn[i], orig);
        }
                                        /* traverse each wall */
        for (gc.w = 0; gc.w < 6; gc.w++) {
                if (!(inflags & 1<<gc.w))       /* origin on wrong side */
                        continue;
                                        /* scanline algorithm */
                for (gc.i[1] = hp->grid[hdwg1[gc.w]]; gc.i[1]--; ) {
                                                /* compute scanline */
                        gp[gc.w>>1] = gc.w&1 ? hp->grid[gc.w>>1] : 0;
                        gp[hdwg0[gc.w]] = 0;
                        gp[hdwg1[gc.w]] = gc.i[1] + 0.5;
                        hdworld(lo, hp, gp);
                        gp[hdwg0[gc.w]] = 1;
                        hdworld(ld, hp, gp);
                        ld[0] -= lo[0]; ld[1] -= lo[1]; ld[2] -= lo[2];
                                                /* find scanline limits */
                        lbeg = 0; lend = hp->grid[hdwg0[gc.w]];
                        for (i = 0; i < 4; i++) {
                                t = DOT(pn[i], lo) - po[i];
                                d = -DOT(pn[i], ld);
                                if (d > FTINY) {                /* <- plane */
                                        if ((t /= d) < lend)
                                                lend = t;
                                } else if (d < -FTINY) {        /* plane -> */
                                        if ((t /= d) > lbeg)
                                                lbeg = t;
                                } else if (t < 0) {             /* outside */
                                        lend = -1;
                                        break;
                                }
                        }
                        if (lbeg >= lend)
                                continue;
                        i = lend + .5;          /* visit cells on this scan */
                        for (gc.i[0] = lbeg + .5; gc.i[0] < i; gc.i[0]++) {
                                n += (*vf)(&gc, dp);
                                ncalls++;
                        }
                }
        }
        if (ncalls)                     /* got one at least */
                return(n);
                                        /* else find closest cell */
        VSUM(ld, pyrd[0], pyrd[1], 1.);
        VSUM(ld, ld, pyrd[2], 1.);
        VSUM(ld, ld, pyrd[3], 1.);
#if 0
        if (normalize(ld) == 0.0)       /* technically not necessary */
                return(0);
#endif
        d = hdinter(gc2, NULL, &t, hp, orig, ld);
        if (d >= FHUGE || t <= 0.)
                return(0);
        return((*vf)(gc2+1, dp));       /* visit it */
}


sect_behind(hp, vp)             /* check if section is "behind" viewpoint */
register HOLO   *hp;
register VIEW   *vp;
{
        FVECT   hcent;
                                        /* compute holodeck section center */
        VSUM(hcent, hp->orig, hp->xv[0], 0.5);
        VSUM(hcent, hcent, hp->xv[1], 0.5);
        VSUM(hcent, hcent, hp->xv[2], 0.5);
                                        /* behind if center is behind */
        return(DOT(vp->vdir,hcent) < DOT(vp->vdir,vp->vp));
}


viewpyramid(org, dir, hp, vp)   /* compute view pyramid */
FVECT   org, dir[4];
HOLO    *hp;
VIEW    *vp;
{
        register int    i;
                                        /* check view type */
        if (vp->type == VT_PAR)
                return(0);
                                        /* in front or behind? */
        if (!sect_behind(hp, vp)) {
                if (viewray(org, dir[0], vp, 0., 0.) < -FTINY)
                        return(0);
                if (viewray(org, dir[1], vp, 0., 1.) < -FTINY)
                        return(0);
                if (viewray(org, dir[2], vp, 1., 1.) < -FTINY)
                        return(0);
                if (viewray(org, dir[3], vp, 1., 0.) < -FTINY)
                        return(0);
                return(1);
        }                               /* reverse pyramid */
        if (viewray(org, dir[3], vp, 0., 0.) < -FTINY)
                return(0);
        if (viewray(org, dir[2], vp, 0., 1.) < -FTINY)
                return(0);
        if (viewray(org, dir[1], vp, 1., 1.) < -FTINY)
                return(0);
        if (viewray(org, dir[0], vp, 1., 0.) < -FTINY)
                return(0);
        for (i = 0; i < 3; i++) {
                dir[0][i] = -dir[0][i];
                dir[1][i] = -dir[1][i];
                dir[2][i] = -dir[2][i];
                dir[3][i] = -dir[3][i];
        }
        return(-1);
}


int
addcell(gcp, cl)                /* add a cell to a list */
GCOORD  *gcp;
register struct cellist *cl;
{
        *(cl->cl+cl->n) = *gcp;
        cl->n++;
        return(1);
}


int
cellcmp(gcp1, gcp2)             /* visit_cells() cell ordering */
register GCOORD *gcp1, *gcp2;
{
        register int    c;

        if ((c = gcp1->w - gcp2->w))
                return(c);
        if ((c = gcp2->i[1] - gcp1->i[1]))      /* wg1 is reverse-ordered */
                return(c);
        return(gcp1->i[0] - gcp2->i[0]);
}


GCOORD *
getviewcells(np, hp, vp)        /* get ordered cell list for section view */
int     *np;            /* returned number of cells (negative if reversed) */
register HOLO   *hp;
VIEW    *vp;
{
        FVECT   org, dir[4];
        int     orient;
        struct cellist  cl;
                                        /* compute view pyramid */
        *np = 0;
        orient = viewpyramid(org, dir, hp, vp);
        if (!orient)
                return(NULL);
                                        /* allocate enough list space */
        cl.n = 2*(      hp->grid[0]*hp->grid[1] +
                        hp->grid[0]*hp->grid[2] +
                        hp->grid[1]*hp->grid[2] );
        cl.cl = (GCOORD *)malloc(cl.n*sizeof(GCOORD));
        if (cl.cl == NULL)
                goto memerr;
        cl.n = 0;                       /* add cells within pyramid */
        visit_cells(org, dir, hp, addcell, (char *)&cl);
        if (!cl.n) {
                free((void *)cl.cl);
                return(NULL);
        }
        *np = cl.n * orient;
#if 0
        /* We're just going to free this memory in a moment, and list is
         * sorted automatically by visit_cells(), so we don't need this.
         */
                                        /* optimize memory use */
        cl.cl = (GCOORD *)realloc((void *)cl.cl, cl.n*sizeof(GCOORD));
        if (cl.cl == NULL)
                goto memerr;
                                        /* sort the list */
        qsort((char *)cl.cl, cl.n, sizeof(GCOORD), cellcmp);
#endif
        return(cl.cl);
memerr:
        error(SYSTEM, "out of memory in getviewcells");
}


extern void
gridlines(                      /* run through holodeck section grid lines */
        void    (*f)(FVECT wp[2])
)
{
        register int    hd, w, i;
        int     g0, g1;
        FVECT   wp[2], mov;
        double  d;
                                        /* do each wall on each section */
        for (hd = 0; hdlist[hd] != NULL; hd++)
                for (w = 0; w < 6; w++) {
                        g0 = hdwg0[w];
                        g1 = hdwg1[w];
                        d = 1.0/hdlist[hd]->grid[g0];
                        mov[0] = d * hdlist[hd]->xv[g0][0];
                        mov[1] = d * hdlist[hd]->xv[g0][1];
                        mov[2] = d * hdlist[hd]->xv[g0][2];
                        if (w & 1) {
                                VSUM(wp[0], hdlist[hd]->orig,
                                                hdlist[hd]->xv[w>>1], 1.);
                                VSUM(wp[0], wp[0], mov, 1.);
                        } else
                                VCOPY(wp[0], hdlist[hd]->orig);
                        VSUM(wp[1], wp[0], hdlist[hd]->xv[g1], 1.);
                        for (i = hdlist[hd]->grid[g0]; ; ) {    /* g0 lines */
                                (*f)(wp);
                                if (!--i) break;
                                wp[0][0] += mov[0]; wp[0][1] += mov[1];
                                wp[0][2] += mov[2]; wp[1][0] += mov[0];
                                wp[1][1] += mov[1]; wp[1][2] += mov[2];
                        }
                        d = 1.0/hdlist[hd]->grid[g1];
                        mov[0] = d * hdlist[hd]->xv[g1][0];
                        mov[1] = d * hdlist[hd]->xv[g1][1];
                        mov[2] = d * hdlist[hd]->xv[g1][2];
                        if (w & 1)
                                VSUM(wp[0], hdlist[hd]->orig,
                                                hdlist[hd]->xv[w>>1], 1.);
                        else
                                VSUM(wp[0], hdlist[hd]->orig, mov, 1.);
                        VSUM(wp[1], wp[0], hdlist[hd]->xv[g0], 1.);
                        for (i = hdlist[hd]->grid[g1]; ; ) {    /* g1 lines */
                                (*f)(wp);
                                if (!--i) break;
                                wp[0][0] += mov[0]; wp[0][1] += mov[1];
                                wp[0][2] += mov[2]; wp[1][0] += mov[0];
                                wp[1][1] += mov[1]; wp[1][2] += mov[2];
                        }
                }
}
Revision:	3.15
Committed:	Thu Jan 1 11:21:55 2004 UTC (21 years, 9 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 3.14:	+5 -3 lines
Log Message:	Ansification and prototypes.
#	User	Rev	Content
1	gregl	3.1	#ifndef lint
2	schorsch	3.15	static const char RCSid[] = "$Id: rhdisp3.c,v 3.14 2003/07/21 22:30:18 schorsch Exp $";
3	gregl	3.1	#endif
4			/*
5	gregl	3.2	* Holodeck beam support for display process
6	gregl	3.1	*/
7
8			#include "rholo.h"
9			#include "rhdisp.h"
10			#include "view.h"
11
12	gregl	3.4	struct cellist {
13			GCOORD *cl;
14			int n;
15			};
16	gregl	3.1
17	gregl	3.4
18	gregl	3.1	int
19	gwlarson	3.10	npixels(vp, hr, vr, hp, bi) /* compute appropriate nrays to evaluate */
20	gregl	3.5	register VIEW *vp;
21	gregl	3.1	int hr, vr;
22			HOLO *hp;
23			int bi;
24			{
25	gregl	3.5	VIEW vrev;
26	gregl	3.1	GCOORD gc[2];
27	gwlarson	3.10	FVECT cp[4], ip[4], pf, pb;
28			double af, ab, sf2, sb2, dfb2, df2, db2, penalty;
29	gregl	3.1	register int i;
30	gwlarson	3.11	/* special case */
31			if (hr <= 0 \| vr <= 0)
32			return(0);
33	gregl	3.1	/* compute cell corners in image */
34			if (!hdbcoord(gc, hp, bi))
35			error(CONSISTENCY, "bad beam index in npixels");
36	gregl	3.5	hdcell(cp, hp, gc+1); /* find cell on front image */
37	gwlarson	3.10	for (i = 3; i--; ) /* compute front center */
38			pf[i] = 0.5*(cp[0][i] + cp[2][i]);
39			sf2 = 0.25dist2(cp[0], cp[2]); / compute half diagonal length */
40			for (i = 0; i < 4; i++) { /* compute visible quad */
41	gregl	3.5	viewloc(ip[i], vp, cp[i]);
42			if (ip[i][2] < 0.) {
43			af = 0;
44			goto getback;
45	gregl	3.4	}
46	gregl	3.5	ip[i][0] = (double)hr; / scale by resolution */
47			ip[i][1] *= (double)vr;
48	gregl	3.4	}
49	gregl	3.5	/* compute front area */
50			af = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
51			(ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
52			af += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
53			(ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
54	gwlarson	3.10	af *= af >= 0 ? 0.5 : -0.5;
55	gregl	3.5	getback:
56	schorsch	3.14	vrev = vp; / compute reverse view */
57	gregl	3.5	for (i = 0; i < 3; i++) {
58			vrev.vdir[i] = -vp->vdir[i];
59			vrev.vup[i] = -vp->vup[i];
60			vrev.hvec[i] = -vp->hvec[i];
61			vrev.vvec[i] = -vp->vvec[i];
62			}
63			hdcell(cp, hp, gc); /* find cell on back image */
64	gwlarson	3.10	for (i = 3; i--; ) /* compute rear center */
65			pb[i] = 0.5*(cp[0][i] + cp[2][i]);
66			sb2 = 0.25dist2(cp[0], cp[2]); / compute half diagonal length */
67			for (i = 0; i < 4; i++) { /* compute visible quad */
68	gregl	3.5	viewloc(ip[i], &vrev, cp[i]);
69	gwlarson	3.10	if (ip[i][2] < 0.) {
70			ab = 0;
71			goto finish;
72			}
73	gregl	3.1	ip[i][0] = (double)hr; / scale by resolution */
74			ip[i][1] *= (double)vr;
75			}
76	gregl	3.5	/* compute back area */
77			ab = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) -
78	gregl	3.1	(ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]);
79	gregl	3.5	ab += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) -
80	gregl	3.1	(ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]);
81	gwlarson	3.10	ab *= ab >= 0 ? 0.5 : -0.5;
82			finish: /* compute penalty based on dist. sightline - viewpoint */
83			df2 = dist2(vp->vp, pf);
84			db2 = dist2(vp->vp, pb);
85			dfb2 = dist2(pf, pb);
86			penalty = dfb2 + df2 - db2;
87			penalty = df2 - 0.25penaltypenalty/dfb2;
88			if (df2 > db2) penalty /= df2 <= dfb2 ? sb2 : sb2*df2/dfb2;
89			else penalty /= db2 <= dfb2 ? sf2 : sf2*db2/dfb2;
90			if (penalty < 1.) penalty = 1.;
91			/* round off smaller non-zero area */
92			if (ab <= FTINY \|\| (af > FTINY && af <= ab))
93			return((int)(af/penalty + 0.5));
94			return((int)(ab/penalty + 0.5));
95	gregl	3.1	}
96
97
98			/*
99			* The ray directions that define the pyramid in visit_cells() needn't
100			* be normalized, but they must be given in clockwise order as seen
101			* from the pyramid's apex (origin).
102	gregl	3.8	* If no cell centers fall within the domain, the closest cell is visited.
103	gregl	3.1	*/
104			int
105			visit_cells(orig, pyrd, hp, vf, dp) /* visit cells within a pyramid */
106			FVECT orig, pyrd[4]; /* pyramid ray directions in clockwise order */
107	gregl	3.8	register HOLO *hp;
108	gregl	3.1	int (*vf)();
109			char *dp;
110			{
111	gregl	3.8	int ncalls = 0, n = 0;
112	gregl	3.1	int inflags = 0;
113			FVECT gp, pn[4], lo, ld;
114			double po[4], lbeg, lend, d, t;
115	gregl	3.8	GCOORD gc, gc2[2];
116	gregl	3.1	register int i;
117			/* figure out whose side we're on */
118			hdgrid(gp, hp, orig);
119			for (i = 0; i < 3; i++) {
120			inflags \|= (gp[i] > FTINY) << (i<<1);
121			inflags \|= (gp[i] < hp->grid[i]-FTINY) << (i<<1 \| 1);
122			}
123			/* compute pyramid planes */
124			for (i = 0; i < 4; i++) {
125			fcross(pn[i], pyrd[i], pyrd[(i+1)&03]);
126			po[i] = DOT(pn[i], orig);
127			}
128			/* traverse each wall */
129			for (gc.w = 0; gc.w < 6; gc.w++) {
130			if (!(inflags & 1<<gc.w)) /* origin on wrong side */
131			continue;
132			/* scanline algorithm */
133	gregl	3.9	for (gc.i[1] = hp->grid[hdwg1[gc.w]]; gc.i[1]--; ) {
134	gregl	3.1	/* compute scanline */
135			gp[gc.w>>1] = gc.w&1 ? hp->grid[gc.w>>1] : 0;
136	gregl	3.9	gp[hdwg0[gc.w]] = 0;
137			gp[hdwg1[gc.w]] = gc.i[1] + 0.5;
138	gregl	3.1	hdworld(lo, hp, gp);
139	gregl	3.9	gp[hdwg0[gc.w]] = 1;
140	gregl	3.1	hdworld(ld, hp, gp);
141	gregl	3.2	ld[0] -= lo[0]; ld[1] -= lo[1]; ld[2] -= lo[2];
142	gregl	3.1	/* find scanline limits */
143	gregl	3.9	lbeg = 0; lend = hp->grid[hdwg0[gc.w]];
144	gregl	3.1	for (i = 0; i < 4; i++) {
145			t = DOT(pn[i], lo) - po[i];
146			d = -DOT(pn[i], ld);
147	gregl	3.2	if (d > FTINY) { /* <- plane */
148	gregl	3.1	if ((t /= d) < lend)
149			lend = t;
150	gregl	3.2	} else if (d < -FTINY) { /* plane -> */
151	gregl	3.1	if ((t /= d) > lbeg)
152			lbeg = t;
153	gregl	3.3	} else if (t < 0) { /* outside */
154			lend = -1;
155			break;
156			}
157	gregl	3.1	}
158	gregl	3.3	if (lbeg >= lend)
159			continue;
160	gregl	3.1	i = lend + .5; /* visit cells on this scan */
161	gregl	3.8	for (gc.i[0] = lbeg + .5; gc.i[0] < i; gc.i[0]++) {
162	gregl	3.1	n += (*vf)(&gc, dp);
163	gregl	3.8	ncalls++;
164			}
165	gregl	3.1	}
166			}
167	gregl	3.8	if (ncalls) /* got one at least */
168			return(n);
169			/* else find closest cell */
170			VSUM(ld, pyrd[0], pyrd[1], 1.);
171			VSUM(ld, ld, pyrd[2], 1.);
172			VSUM(ld, ld, pyrd[3], 1.);
173			#if 0
174			if (normalize(ld) == 0.0) /* technically not necessary */
175			return(0);
176			#endif
177			d = hdinter(gc2, NULL, &t, hp, orig, ld);
178			if (d >= FHUGE \|\| t <= 0.)
179			return(0);
180			return((vf)(gc2+1, dp)); / visit it */
181	gregl	3.1	}
182
183
184	gregl	3.4	sect_behind(hp, vp) /* check if section is "behind" viewpoint */
185			register HOLO *hp;
186			register VIEW *vp;
187			{
188			FVECT hcent;
189			/* compute holodeck section center */
190			VSUM(hcent, hp->orig, hp->xv[0], 0.5);
191			VSUM(hcent, hcent, hp->xv[1], 0.5);
192			VSUM(hcent, hcent, hp->xv[2], 0.5);
193			/* behind if center is behind */
194			return(DOT(vp->vdir,hcent) < DOT(vp->vdir,vp->vp));
195			}
196
197
198			viewpyramid(org, dir, hp, vp) /* compute view pyramid */
199			FVECT org, dir[4];
200			HOLO *hp;
201			VIEW *vp;
202			{
203			register int i;
204			/* check view type */
205			if (vp->type == VT_PAR)
206			return(0);
207			/* in front or behind? */
208			if (!sect_behind(hp, vp)) {
209			if (viewray(org, dir[0], vp, 0., 0.) < -FTINY)
210			return(0);
211			if (viewray(org, dir[1], vp, 0., 1.) < -FTINY)
212			return(0);
213			if (viewray(org, dir[2], vp, 1., 1.) < -FTINY)
214			return(0);
215			if (viewray(org, dir[3], vp, 1., 0.) < -FTINY)
216			return(0);
217			return(1);
218			} /* reverse pyramid */
219			if (viewray(org, dir[3], vp, 0., 0.) < -FTINY)
220			return(0);
221			if (viewray(org, dir[2], vp, 0., 1.) < -FTINY)
222			return(0);
223			if (viewray(org, dir[1], vp, 1., 1.) < -FTINY)
224			return(0);
225			if (viewray(org, dir[0], vp, 1., 0.) < -FTINY)
226			return(0);
227			for (i = 0; i < 3; i++) {
228			dir[0][i] = -dir[0][i];
229			dir[1][i] = -dir[1][i];
230			dir[2][i] = -dir[2][i];
231			dir[3][i] = -dir[3][i];
232			}
233			return(-1);
234			}
235
236
237	gregl	3.1	int
238			addcell(gcp, cl) /* add a cell to a list */
239			GCOORD *gcp;
240	gregl	3.4	register struct cellist *cl;
241	gregl	3.1	{
242	schorsch	3.14	(cl->cl+cl->n) = gcp;
243	gregl	3.4	cl->n++;
244	gregl	3.1	return(1);
245			}
246
247
248			int
249			cellcmp(gcp1, gcp2) /* visit_cells() cell ordering */
250			register GCOORD gcp1, gcp2;
251			{
252			register int c;
253
254			if ((c = gcp1->w - gcp2->w))
255			return(c);
256			if ((c = gcp2->i[1] - gcp1->i[1])) /* wg1 is reverse-ordered */
257			return(c);
258			return(gcp1->i[0] - gcp2->i[0]);
259			}
260
261
262	gregl	3.4	GCOORD *
263			getviewcells(np, hp, vp) /* get ordered cell list for section view */
264			int np; / returned number of cells (negative if reversed) */
265	gregl	3.1	register HOLO *hp;
266			VIEW *vp;
267			{
268			FVECT org, dir[4];
269	gregl	3.4	int orient;
270			struct cellist cl;
271	gregl	3.1	/* compute view pyramid */
272	gregl	3.4	*np = 0;
273			orient = viewpyramid(org, dir, hp, vp);
274			if (!orient)
275			return(NULL);
276	gregl	3.1	/* allocate enough list space */
277	gregl	3.4	cl.n = 2( hp->grid[0]hp->grid[1] +
278			hp->grid[0]*hp->grid[2] +
279			hp->grid[1]*hp->grid[2] );
280			cl.cl = (GCOORD )malloc(cl.nsizeof(GCOORD));
281			if (cl.cl == NULL)
282	gregl	3.1	goto memerr;
283	gregl	3.4	cl.n = 0; /* add cells within pyramid */
284	gwlarson	3.11	visit_cells(org, dir, hp, addcell, (char *)&cl);
285	gregl	3.4	if (!cl.n) {
286	greg	3.12	free((void *)cl.cl);
287	gregl	3.1	return(NULL);
288			}
289	gregl	3.4	np = cl.n orient;
290	gregl	3.1	#if 0
291	gregl	3.2	/* We're just going to free this memory in a moment, and list is
292			* sorted automatically by visit_cells(), so we don't need this.
293			*/
294	gregl	3.4	/* optimize memory use */
295	greg	3.13	cl.cl = (GCOORD )realloc((void )cl.cl, cl.n*sizeof(GCOORD));
296	gregl	3.4	if (cl.cl == NULL)
297			goto memerr;
298	gregl	3.1	/* sort the list */
299	gregl	3.4	qsort((char *)cl.cl, cl.n, sizeof(GCOORD), cellcmp);
300	gregl	3.1	#endif
301	gregl	3.4	return(cl.cl);
302	gregl	3.1	memerr:
303			error(SYSTEM, "out of memory in getviewcells");
304			}
305	gregl	3.6
306
307	schorsch	3.15	extern void
308			gridlines( /* run through holodeck section grid lines */
309			void (*f)(FVECT wp[2])
310			)
311	gregl	3.6	{
312			register int hd, w, i;
313			int g0, g1;
314	gregl	3.7	FVECT wp[2], mov;
315	gregl	3.6	double d;
316			/* do each wall on each section */
317			for (hd = 0; hdlist[hd] != NULL; hd++)
318			for (w = 0; w < 6; w++) {
319	gregl	3.9	g0 = hdwg0[w];
320			g1 = hdwg1[w];
321	gregl	3.7	d = 1.0/hdlist[hd]->grid[g0];
322			mov[0] = d * hdlist[hd]->xv[g0][0];
323			mov[1] = d * hdlist[hd]->xv[g0][1];
324			mov[2] = d * hdlist[hd]->xv[g0][2];
325			if (w & 1) {
326	gregl	3.6	VSUM(wp[0], hdlist[hd]->orig,
327			hdlist[hd]->xv[w>>1], 1.);
328	gregl	3.7	VSUM(wp[0], wp[0], mov, 1.);
329			} else
330			VCOPY(wp[0], hdlist[hd]->orig);
331			VSUM(wp[1], wp[0], hdlist[hd]->xv[g1], 1.);
332			for (i = hdlist[hd]->grid[g0]; ; ) { /* g0 lines */
333	gregl	3.6	(*f)(wp);
334	gregl	3.7	if (!--i) break;
335			wp[0][0] += mov[0]; wp[0][1] += mov[1];
336			wp[0][2] += mov[2]; wp[1][0] += mov[0];
337			wp[1][1] += mov[1]; wp[1][2] += mov[2];
338	gregl	3.6	}
339	gregl	3.7	d = 1.0/hdlist[hd]->grid[g1];
340			mov[0] = d * hdlist[hd]->xv[g1][0];
341			mov[1] = d * hdlist[hd]->xv[g1][1];
342			mov[2] = d * hdlist[hd]->xv[g1][2];
343			if (w & 1)
344	gregl	3.6	VSUM(wp[0], hdlist[hd]->orig,
345			hdlist[hd]->xv[w>>1], 1.);
346	gregl	3.7	else
347			VSUM(wp[0], hdlist[hd]->orig, mov, 1.);
348			VSUM(wp[1], wp[0], hdlist[hd]->xv[g0], 1.);
349			for (i = hdlist[hd]->grid[g1]; ; ) { /* g1 lines */
350	gregl	3.6	(*f)(wp);
351	gregl	3.7	if (!--i) break;
352			wp[0][0] += mov[0]; wp[0][1] += mov[1];
353			wp[0][2] += mov[2]; wp[1][0] += mov[0];
354			wp[1][1] += mov[1]; wp[1][2] += mov[2];
355	gregl	3.6	}
356			}
357			}