src/rt/srcsamp.c

/* Copyright (c) 1991 Regents of the University of California */

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

/*
 * Source sampling routines
 */

#include  "ray.h"

#include  "source.h"

#include  "random.h"


double
nextssamp(r, si)                /* compute sample for source, rtn. distance */
register RAY  *r;               /* origin is read, direction is set */
register SRCINDEX  *si;         /* source index (modified to current) */
{
        int  cent[3], size[3], parr[2];
        FVECT  vpos;
        double  d;
        register int  i;

        while (++si->sp >= si->np) {    /* get next sample */
                if (++si->sn >= nsources)
                        return(0.0);    /* no more */
                if (source[si->sn].sflags & SSKIP)
                        si->np = 0;
                else if (srcsizerat <= FTINY)
                        nopart(si, r);
                else {
                        for (i = si->sn; source[i].sflags & SVIRTUAL;
                                        i = source[i].sa.sv.sn)
                                ;               /* partition source */
                        (*sfun[source[i].so->otype].of->partit)(si, r);
                }
                si->sp = -1;
        }
                                        /* get partition */
        cent[0] = cent[1] = cent[2] = 0;
        size[0] = size[1] = size[2] = MAXSPART;
        parr[0] = 0; parr[1] = si->sp;
        if (!skipparts(cent, size, parr, si->spt))
                error(CONSISTENCY, "bad source partition in nextssamp");
                                        /* compute sample */
        if (dstrsrc > FTINY) {                  /* jitter sample */
                dimlist[ndims] = si->sn + 8831;
                dimlist[ndims+1] = si->sp + 3109;
                d = urand(ilhash(dimlist,ndims+2)+samplendx);
                if (source[si->sn].sflags & SFLAT) {
                        multisamp(vpos, 2, d);
                        vpos[2] = 0.5;
                } else
                        multisamp(vpos, 3, d);
                for (i = 0; i < 3; i++)
                        vpos[i] = dstrsrc * (1. - 2.*vpos[i]) *
                                        (double)size[i]/MAXSPART;
        } else
                vpos[0] = vpos[1] = vpos[2] = 0.0;

        for (i = 0; i < 3; i++)
                vpos[i] += (double)cent[i]/MAXSPART;
                                        /* compute direction */
        for (i = 0; i < 3; i++)
                r->rdir[i] = source[si->sn].sloc[i] +
                                vpos[SU]*source[si->sn].ss[SU][i] +
                                vpos[SV]*source[si->sn].ss[SV][i] +
                                vpos[SW]*source[si->sn].ss[SW][i];

        if (!(source[si->sn].sflags & SDISTANT))
                for (i = 0; i < 3; i++)
                        r->rdir[i] -= r->rorg[i];
                                        /* compute distance */
        if ((d = normalize(r->rdir)) == 0.0)
                return(nextssamp(r, si));       /* at source! */

                                        /* compute sample size */
        si->dom  = source[si->sn].ss2;
        if (source[si->sn].sflags & SFLAT) {
                si->dom *= sflatform(si->sn, r->rdir);
                si->dom *= (double)(size[SU]*size[SV])/(MAXSPART*MAXSPART);
        } else if (source[si->sn].sflags & SCYL) {
                si->dom *= scylform(si->sn, r->rdir);
                si->dom *= (double)size[SU]/MAXSPART;
        } else {
                si->dom *= (double)(size[SU]*size[SV]*size[SW]) /
                                (MAXSPART*MAXSPART*MAXSPART) ;
        }
        if (source[si->sn].sflags & SDISTANT)
                return(FHUGE);
        si->dom /= d*d;
        return(d);              /* sample OK, return distance */
}


skipparts(ct, sz, pp, pt)               /* skip to requested partition */
int  ct[3], sz[3];              /* center and size of partition (returned) */
register int  pp[2];            /* current index, number to skip (modified) */
unsigned char  *pt;             /* partition array */
{
        register int  p;
                                        /* check this partition */
        p = spart(pt, pp[0]);
        pp[0]++;
        if (p == S0)                    /* leaf partition */
                if (pp[1]) {
                        pp[1]--;
                        return(0);      /* not there yet */
                } else
                        return(1);      /* we've arrived */
                                /* else check lower */
        sz[p] >>= 1;
        ct[p] -= sz[p];
        if (skipparts(ct, sz, pp, pt))
                return(1);      /* return hit */
                                /* else check upper */
        ct[p] += sz[p] << 1;
        if (skipparts(ct, sz, pp, pt))
                return(1);      /* return hit */
                                /* else return to starting position */
        ct[p] -= sz[p];
        sz[p] <<= 1;
        return(0);              /* return miss */
}


nopart(si, r)                   /* single source partition */
register SRCINDEX  *si;
RAY  *r;
{
        clrpart(si->spt);
        setpart(si->spt, 0, S0);
        si->np = 1;
}


cylpart(si, r)                  /* partition a cylinder */
SRCINDEX  *si;
register RAY  *r;
{
        double  dist2, safedist2, dist2cent, rad2;
        FVECT  v;
        register SRCREC  *sp;
        int  pi;
                                        /* first check point location */
        clrpart(si->spt);
        sp = source + si->sn;
        rad2 = 1.365 * DOT(sp->ss[SV],sp->ss[SV]);
        v[0] = r->rorg[0] - sp->sloc[0];
        v[1] = r->rorg[1] - sp->sloc[1];
        v[2] = r->rorg[2] - sp->sloc[2];
        dist2 = DOT(v,sp->ss[SU]);
        safedist2 = DOT(sp->ss[SU],sp->ss[SU]);
        dist2 *= dist2 / safedist2;
        dist2cent = DOT(v,v);
        dist2 = dist2cent - dist2;
        if (dist2 <= rad2) {            /* point inside extended cylinder */
                si->np = 0;
                return;
        }
        safedist2 *= 4.*r->rweight*r->rweight/(srcsizerat*srcsizerat);
        if (dist2 <= 4.*rad2 ||         /* point too close to subdivide */
                        dist2cent >= safedist2) {       /* or too far */
                setpart(si->spt, 0, S0);
                si->np = 1;
                return;
        }
        pi = 0;
        si->np = cyl_partit(r->rorg, si->spt, &pi, MAXSPART,
                        sp->sloc, sp->ss[SU], safedist2);
}


static int
cyl_partit(ro, pt, pi, mp, cent, axis, d2)      /* slice a cylinder */
FVECT  ro;
unsigned char  *pt;
register int  *pi;
int  mp;
FVECT  cent, axis;
double  d2;
{
        FVECT  newct, newax;
        int  npl, npu;

        if (mp < 2 || dist2(ro, cent) >= d2) {  /* hit limit? */
                setpart(pt, *pi, S0);
                (*pi)++;
                return(1);
        }
                                        /* subdivide */
        setpart(pt, *pi, SU);
        (*pi)++;
        newax[0] = .5*axis[0];
        newax[1] = .5*axis[1];
        newax[2] = .5*axis[2];
        d2 *= 0.25;
                                        /* lower half */
        newct[0] = cent[0] - newax[0];
        newct[1] = cent[1] - newax[1];
        newct[2] = cent[2] - newax[2];
        npl = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
                                        /* upper half */
        newct[0] = cent[0] + newax[0];
        newct[1] = cent[1] + newax[1];
        newct[2] = cent[2] + newax[2];
        npu = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
                                        /* return total */
        return(npl + npu);
}


flatpart(si, r)                         /* partition a flat source */
register SRCINDEX  *si;
register RAY  *r;
{
        register FLOAT  *vp;
        FVECT  v;
        double  du2, dv2;
        int  pi;

        clrpart(si->spt);
        vp = source[si->sn].sloc;
        v[0] = r->rorg[0] - vp[0];
        v[1] = r->rorg[1] - vp[1];
        v[2] = r->rorg[2] - vp[2];
        vp = source[si->sn].snorm;
        if (DOT(v,vp) <= FTINY) {       /* behind source */
                si->np = 0;
                return;
        }
        dv2 = 2.*r->rweight/srcsizerat;
        dv2 *= dv2;
        vp = source[si->sn].ss[SU];
        du2 = dv2 * DOT(vp,vp);
        vp = source[si->sn].ss[SV];
        dv2 *= DOT(vp,vp);
        pi = 0;
        si->np = flt_partit(r->rorg, si->spt, &pi, MAXSPART,
                source[si->sn].sloc,
                source[si->sn].ss[SU], source[si->sn].ss[SV], du2, dv2);
}


static int
flt_partit(ro, pt, pi, mp, cent, u, v, du2, dv2)        /* partition flatty */
FVECT  ro;
unsigned char  *pt;
register int  *pi;
int  mp;
FVECT  cent, u, v;
double  du2, dv2;
{
        double  d2;
        FVECT  newct, newax;
        int  npl, npu;

        if (mp < 2 || ((d2 = dist2(ro, cent)) >= du2
                        && d2 >= dv2)) {        /* hit limit? */
                setpart(pt, *pi, S0);
                (*pi)++;
                return(1);
        }
        if (du2 > dv2) {                        /* subdivide in U */
                setpart(pt, *pi, SU);
                (*pi)++;
                newax[0] = .5*u[0];
                newax[1] = .5*u[1];
                newax[2] = .5*u[2];
                u = newax;
                du2 *= 0.25;
        } else {                                /* subdivide in V */
                setpart(pt, *pi, SV);
                (*pi)++;
                newax[0] = .5*v[0];
                newax[1] = .5*v[1];
                newax[2] = .5*v[2];
                v = newax;
                dv2 *= 0.25;
        }
                                        /* lower half */
        newct[0] = cent[0] - newax[0];
        newct[1] = cent[1] - newax[1];
        newct[2] = cent[2] - newax[2];
        npl = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
                                        /* upper half */
        newct[0] = cent[0] + newax[0];
        newct[1] = cent[1] + newax[1];
        newct[2] = cent[2] + newax[2];
        npu = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
                                /* return total */
        return(npl + npu);
}


double
scylform(sn, dir)               /* compute cosine for cylinder's projection */
int  sn;
register FVECT  dir;            /* assume normalized */
{
        register FLOAT  *dv;
        double  d;

        dv = source[sn].ss[SU];
        d = DOT(dir, dv);
        d *= d / DOT(dv,dv);
        return(sqrt(1. - d));
}
Revision:	1.7
Committed:	Mon Oct 28 08:07:44 1991 UTC (32 years, 6 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.6:	+3 -1 lines
Log Message:	fixed bug where nextssamp() included SSKIP sources
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1991 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Source sampling routines
9			*/
10
11	greg	1.4	#include "ray.h"
12	greg	1.1
13			#include "source.h"
14
15			#include "random.h"
16
17
18			double
19	greg	1.4	nextssamp(r, si) /* compute sample for source, rtn. distance */
20			register RAY r; / origin is read, direction is set */
21	greg	1.1	register SRCINDEX si; / source index (modified to current) */
22			{
23			int cent[3], size[3], parr[2];
24			FVECT vpos;
25			double d;
26			register int i;
27	greg	1.5
28	greg	1.1	while (++si->sp >= si->np) { /* get next sample */
29			if (++si->sn >= nsources)
30			return(0.0); /* no more */
31	greg	1.7	if (source[si->sn].sflags & SSKIP)
32			si->np = 0;
33			else if (srcsizerat <= FTINY)
34	greg	1.4	nopart(si, r);
35	greg	1.1	else {
36			for (i = si->sn; source[i].sflags & SVIRTUAL;
37			i = source[i].sa.sv.sn)
38			; /* partition source */
39	greg	1.4	(*sfun[source[i].so->otype].of->partit)(si, r);
40	greg	1.1	}
41			si->sp = -1;
42			}
43			/* get partition */
44			cent[0] = cent[1] = cent[2] = 0;
45			size[0] = size[1] = size[2] = MAXSPART;
46			parr[0] = 0; parr[1] = si->sp;
47			if (!skipparts(cent, size, parr, si->spt))
48			error(CONSISTENCY, "bad source partition in nextssamp");
49			/* compute sample */
50			if (dstrsrc > FTINY) { /* jitter sample */
51			dimlist[ndims] = si->sn + 8831;
52			dimlist[ndims+1] = si->sp + 3109;
53			d = urand(ilhash(dimlist,ndims+2)+samplendx);
54			if (source[si->sn].sflags & SFLAT) {
55			multisamp(vpos, 2, d);
56			vpos[2] = 0.5;
57			} else
58			multisamp(vpos, 3, d);
59			for (i = 0; i < 3; i++)
60			vpos[i] = dstrsrc * (1. - 2.vpos[i])
61			(double)size[i]/MAXSPART;
62			} else
63			vpos[0] = vpos[1] = vpos[2] = 0.0;
64
65			for (i = 0; i < 3; i++)
66			vpos[i] += (double)cent[i]/MAXSPART;
67			/* compute direction */
68			for (i = 0; i < 3; i++)
69	greg	1.4	r->rdir[i] = source[si->sn].sloc[i] +
70	greg	1.1	vpos[SU]*source[si->sn].ss[SU][i] +
71			vpos[SV]*source[si->sn].ss[SV][i] +
72			vpos[SW]*source[si->sn].ss[SW][i];
73
74			if (!(source[si->sn].sflags & SDISTANT))
75			for (i = 0; i < 3; i++)
76	greg	1.4	r->rdir[i] -= r->rorg[i];
77	greg	1.1	/* compute distance */
78	greg	1.4	if ((d = normalize(r->rdir)) == 0.0)
79	greg	1.5	return(nextssamp(r, si)); /* at source! */
80	greg	1.1
81			/* compute sample size */
82			si->dom = source[si->sn].ss2;
83			if (source[si->sn].sflags & SFLAT) {
84	greg	1.4	si->dom *= sflatform(si->sn, r->rdir);
85	greg	1.1	si->dom = (double)(size[SU]size[SV])/(MAXSPART*MAXSPART);
86			} else if (source[si->sn].sflags & SCYL) {
87	greg	1.4	si->dom *= scylform(si->sn, r->rdir);
88	greg	1.1	si->dom *= (double)size[SU]/MAXSPART;
89			} else {
90			si->dom = (double)(size[SU]size[SV]*size[SW]) /
91			(MAXSPARTMAXSPARTMAXSPART) ;
92			}
93			if (source[si->sn].sflags & SDISTANT)
94			return(FHUGE);
95			si->dom /= d*d;
96			return(d); /* sample OK, return distance */
97			}
98
99
100			skipparts(ct, sz, pp, pt) /* skip to requested partition */
101			int ct[3], sz[3]; /* center and size of partition (returned) */
102			register int pp[2]; /* current index, number to skip (modified) */
103			unsigned char pt; / partition array */
104			{
105			register int p;
106			/* check this partition */
107			p = spart(pt, pp[0]);
108			pp[0]++;
109			if (p == S0) /* leaf partition */
110			if (pp[1]) {
111			pp[1]--;
112			return(0); /* not there yet */
113			} else
114			return(1); /* we've arrived */
115			/* else check lower */
116			sz[p] >>= 1;
117			ct[p] -= sz[p];
118			if (skipparts(ct, sz, pp, pt))
119			return(1); /* return hit */
120			/* else check upper */
121			ct[p] += sz[p] << 1;
122			if (skipparts(ct, sz, pp, pt))
123			return(1); /* return hit */
124			/* else return to starting position */
125			ct[p] -= sz[p];
126			sz[p] <<= 1;
127			return(0); /* return miss */
128			}
129
130
131	greg	1.4	nopart(si, r) /* single source partition */
132	greg	1.1	register SRCINDEX *si;
133	greg	1.4	RAY *r;
134	greg	1.1	{
135			clrpart(si->spt);
136			setpart(si->spt, 0, S0);
137			si->np = 1;
138			}
139
140
141	greg	1.4	cylpart(si, r) /* partition a cylinder */
142	greg	1.1	SRCINDEX *si;
143	greg	1.4	register RAY *r;
144	greg	1.1	{
145			double dist2, safedist2, dist2cent, rad2;
146			FVECT v;
147			register SRCREC *sp;
148			int pi;
149			/* first check point location */
150			clrpart(si->spt);
151	greg	1.4	sp = source + si->sn;
152	greg	1.3	rad2 = 1.365 * DOT(sp->ss[SV],sp->ss[SV]);
153	greg	1.4	v[0] = r->rorg[0] - sp->sloc[0];
154			v[1] = r->rorg[1] - sp->sloc[1];
155			v[2] = r->rorg[2] - sp->sloc[2];
156	greg	1.1	dist2 = DOT(v,sp->ss[SU]);
157			safedist2 = DOT(sp->ss[SU],sp->ss[SU]);
158			dist2 *= dist2 / safedist2;
159			dist2cent = DOT(v,v);
160			dist2 = dist2cent - dist2;
161			if (dist2 <= rad2) { /* point inside extended cylinder */
162			si->np = 0;
163			return;
164			}
165	greg	1.4	safedist2 = 4.r->rweightr->rweight/(srcsizeratsrcsizerat);
166	greg	1.5	if (dist2 <= 4.rad2 \|\| / point too close to subdivide */
167			dist2cent >= safedist2) { /* or too far */
168	greg	1.1	setpart(si->spt, 0, S0);
169			si->np = 1;
170			return;
171			}
172			pi = 0;
173	greg	1.4	si->np = cyl_partit(r->rorg, si->spt, &pi, MAXSPART,
174	greg	1.1	sp->sloc, sp->ss[SU], safedist2);
175			}
176
177
178			static int
179			cyl_partit(ro, pt, pi, mp, cent, axis, d2) /* slice a cylinder */
180			FVECT ro;
181			unsigned char *pt;
182			register int *pi;
183			int mp;
184			FVECT cent, axis;
185			double d2;
186			{
187			FVECT newct, newax;
188			int npl, npu;
189
190			if (mp < 2 \|\| dist2(ro, cent) >= d2) { /* hit limit? */
191			setpart(pt, *pi, S0);
192			(*pi)++;
193			return(1);
194			}
195			/* subdivide */
196			setpart(pt, *pi, SU);
197			(*pi)++;
198			newax[0] = .5*axis[0];
199			newax[1] = .5*axis[1];
200			newax[2] = .5*axis[2];
201			d2 *= 0.25;
202			/* lower half */
203			newct[0] = cent[0] - newax[0];
204			newct[1] = cent[1] - newax[1];
205			newct[2] = cent[2] - newax[2];
206	greg	1.2	npl = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
207	greg	1.1	/* upper half */
208			newct[0] = cent[0] + newax[0];
209			newct[1] = cent[1] + newax[1];
210			newct[2] = cent[2] + newax[2];
211	greg	1.2	npu = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
212	greg	1.1	/* return total */
213			return(npl + npu);
214			}
215
216
217	greg	1.4	flatpart(si, r) /* partition a flat source */
218	greg	1.1	register SRCINDEX *si;
219	greg	1.5	register RAY *r;
220	greg	1.1	{
221	greg	1.6	register FLOAT *vp;
222	greg	1.5	FVECT v;
223	greg	1.1	double du2, dv2;
224			int pi;
225
226	greg	1.5	clrpart(si->spt);
227			vp = source[si->sn].sloc;
228			v[0] = r->rorg[0] - vp[0];
229			v[1] = r->rorg[1] - vp[1];
230			v[2] = r->rorg[2] - vp[2];
231			vp = source[si->sn].snorm;
232			if (DOT(v,vp) <= FTINY) { /* behind source */
233			si->np = 0;
234			return;
235			}
236	greg	1.4	dv2 = 2.*r->rweight/srcsizerat;
237			dv2 *= dv2;
238	greg	1.1	vp = source[si->sn].ss[SU];
239	greg	1.4	du2 = dv2 * DOT(vp,vp);
240	greg	1.1	vp = source[si->sn].ss[SV];
241	greg	1.4	dv2 *= DOT(vp,vp);
242	greg	1.1	pi = 0;
243	greg	1.4	si->np = flt_partit(r->rorg, si->spt, &pi, MAXSPART,
244			source[si->sn].sloc,
245	greg	1.1	source[si->sn].ss[SU], source[si->sn].ss[SV], du2, dv2);
246			}
247
248
249			static int
250			flt_partit(ro, pt, pi, mp, cent, u, v, du2, dv2) /* partition flatty */
251			FVECT ro;
252			unsigned char *pt;
253			register int *pi;
254			int mp;
255			FVECT cent, u, v;
256			double du2, dv2;
257			{
258			double d2;
259			FVECT newct, newax;
260			int npl, npu;
261
262			if (mp < 2 \|\| ((d2 = dist2(ro, cent)) >= du2
263			&& d2 >= dv2)) { /* hit limit? */
264			setpart(pt, *pi, S0);
265			(*pi)++;
266			return(1);
267			}
268			if (du2 > dv2) { /* subdivide in U */
269			setpart(pt, *pi, SU);
270			(*pi)++;
271			newax[0] = .5*u[0];
272			newax[1] = .5*u[1];
273			newax[2] = .5*u[2];
274			u = newax;
275			du2 *= 0.25;
276			} else { /* subdivide in V */
277			setpart(pt, *pi, SV);
278			(*pi)++;
279			newax[0] = .5*v[0];
280			newax[1] = .5*v[1];
281			newax[2] = .5*v[2];
282			v = newax;
283			dv2 *= 0.25;
284			}
285			/* lower half */
286			newct[0] = cent[0] - newax[0];
287			newct[1] = cent[1] - newax[1];
288			newct[2] = cent[2] - newax[2];
289	greg	1.2	npl = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
290	greg	1.1	/* upper half */
291			newct[0] = cent[0] + newax[0];
292			newct[1] = cent[1] + newax[1];
293			newct[2] = cent[2] + newax[2];
294	greg	1.2	npu = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
295	greg	1.1	/* return total */
296			return(npl + npu);
297			}
298
299
300			double
301			scylform(sn, dir) /* compute cosine for cylinder's projection */
302			int sn;
303			register FVECT dir; /* assume normalized */
304			{
305	greg	1.6	register FLOAT *dv;
306	greg	1.1	double d;
307
308			dv = source[sn].ss[SU];
309			d = DOT(dir, dv);
310			d *= d / DOT(dv,dv);
311			return(sqrt(1. - d));
312			}