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"


static int  cyl_partit(), flt_partit();


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;
nextsample:
        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)
                goto nextsample;                /* at source! */

                                        /* compute sample size */
        if (source[si->sn].sflags & SFLAT) {
                si->dom = sflatform(si->sn, r->rdir);
                si->dom *= size[SU]*size[SV]/(MAXSPART*(double)MAXSPART);
        } else if (source[si->sn].sflags & SCYL) {
                si->dom = scylform(si->sn, r->rdir);
                si->dom *= size[SU]/(double)MAXSPART;
        } else {
                si->dom = size[SU]*size[SV]*(double)size[SW] /
                                (MAXSPART*MAXSPART*(double)MAXSPART) ;
        }
        if (source[si->sn].sflags & SDISTANT) {
                si->dom *= source[si->sn].ss2;
                return(FHUGE);
        }
        if (si->dom <= 1e-4)
                goto nextsample;                /* behind source? */
        si->dom *= source[si->sn].ss2/(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:	2.6
Committed:	Wed Jul 20 12:48:44 1994 UTC (29 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.5:	+7 -6 lines
Log Message:	fixed bug for very small local 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	greg	2.5	static int cyl_partit(), flt_partit();
19
20
21	greg	1.1	double
22	greg	1.4	nextssamp(r, si) /* compute sample for source, rtn. distance */
23			register RAY r; / origin is read, direction is set */
24	greg	1.1	register SRCINDEX si; / source index (modified to current) */
25			{
26			int cent[3], size[3], parr[2];
27			FVECT vpos;
28			double d;
29			register int i;
30	greg	2.2	nextsample:
31	greg	1.1	while (++si->sp >= si->np) { /* get next sample */
32			if (++si->sn >= nsources)
33			return(0.0); /* no more */
34	greg	1.7	if (source[si->sn].sflags & SSKIP)
35			si->np = 0;
36			else if (srcsizerat <= FTINY)
37	greg	1.4	nopart(si, r);
38	greg	1.1	else {
39			for (i = si->sn; source[i].sflags & SVIRTUAL;
40			i = source[i].sa.sv.sn)
41			; /* partition source */
42	greg	1.4	(*sfun[source[i].so->otype].of->partit)(si, r);
43	greg	1.1	}
44			si->sp = -1;
45			}
46			/* get partition */
47			cent[0] = cent[1] = cent[2] = 0;
48			size[0] = size[1] = size[2] = MAXSPART;
49			parr[0] = 0; parr[1] = si->sp;
50			if (!skipparts(cent, size, parr, si->spt))
51			error(CONSISTENCY, "bad source partition in nextssamp");
52			/* compute sample */
53			if (dstrsrc > FTINY) { /* jitter sample */
54			dimlist[ndims] = si->sn + 8831;
55			dimlist[ndims+1] = si->sp + 3109;
56			d = urand(ilhash(dimlist,ndims+2)+samplendx);
57			if (source[si->sn].sflags & SFLAT) {
58			multisamp(vpos, 2, d);
59			vpos[2] = 0.5;
60			} else
61			multisamp(vpos, 3, d);
62			for (i = 0; i < 3; i++)
63			vpos[i] = dstrsrc * (1. - 2.vpos[i])
64			(double)size[i]/MAXSPART;
65			} else
66			vpos[0] = vpos[1] = vpos[2] = 0.0;
67
68			for (i = 0; i < 3; i++)
69			vpos[i] += (double)cent[i]/MAXSPART;
70			/* compute direction */
71			for (i = 0; i < 3; i++)
72	greg	1.4	r->rdir[i] = source[si->sn].sloc[i] +
73	greg	1.1	vpos[SU]*source[si->sn].ss[SU][i] +
74			vpos[SV]*source[si->sn].ss[SV][i] +
75			vpos[SW]*source[si->sn].ss[SW][i];
76
77			if (!(source[si->sn].sflags & SDISTANT))
78			for (i = 0; i < 3; i++)
79	greg	1.4	r->rdir[i] -= r->rorg[i];
80	greg	1.1	/* compute distance */
81	greg	1.4	if ((d = normalize(r->rdir)) == 0.0)
82	greg	2.2	goto nextsample; /* at source! */
83	greg	1.1
84			/* compute sample size */
85			if (source[si->sn].sflags & SFLAT) {
86	greg	2.6	si->dom = sflatform(si->sn, r->rdir);
87	greg	2.4	si->dom = size[SU]size[SV]/(MAXSPART*(double)MAXSPART);
88	greg	1.1	} else if (source[si->sn].sflags & SCYL) {
89	greg	2.6	si->dom = scylform(si->sn, r->rdir);
90	greg	2.4	si->dom *= size[SU]/(double)MAXSPART;
91	greg	1.1	} else {
92	greg	2.6	si->dom = size[SU]size[SV](double)size[SW] /
93	greg	2.4	(MAXSPARTMAXSPART(double)MAXSPART) ;
94	greg	1.1	}
95	greg	2.6	if (source[si->sn].sflags & SDISTANT) {
96			si->dom *= source[si->sn].ss2;
97	greg	1.1	return(FHUGE);
98	greg	2.6	}
99	greg	2.3	if (si->dom <= 1e-4)
100	greg	2.2	goto nextsample; /* behind source? */
101	greg	2.6	si->dom = source[si->sn].ss2/(dd);
102	greg	1.1	return(d); /* sample OK, return distance */
103			}
104
105
106			skipparts(ct, sz, pp, pt) /* skip to requested partition */
107			int ct[3], sz[3]; /* center and size of partition (returned) */
108			register int pp[2]; /* current index, number to skip (modified) */
109			unsigned char pt; / partition array */
110			{
111			register int p;
112			/* check this partition */
113			p = spart(pt, pp[0]);
114			pp[0]++;
115			if (p == S0) /* leaf partition */
116			if (pp[1]) {
117			pp[1]--;
118			return(0); /* not there yet */
119			} else
120			return(1); /* we've arrived */
121			/* else check lower */
122			sz[p] >>= 1;
123			ct[p] -= sz[p];
124			if (skipparts(ct, sz, pp, pt))
125			return(1); /* return hit */
126			/* else check upper */
127			ct[p] += sz[p] << 1;
128			if (skipparts(ct, sz, pp, pt))
129			return(1); /* return hit */
130			/* else return to starting position */
131			ct[p] -= sz[p];
132			sz[p] <<= 1;
133			return(0); /* return miss */
134			}
135
136
137	greg	1.4	nopart(si, r) /* single source partition */
138	greg	1.1	register SRCINDEX *si;
139	greg	1.4	RAY *r;
140	greg	1.1	{
141			clrpart(si->spt);
142			setpart(si->spt, 0, S0);
143			si->np = 1;
144			}
145
146
147	greg	1.4	cylpart(si, r) /* partition a cylinder */
148	greg	1.1	SRCINDEX *si;
149	greg	1.4	register RAY *r;
150	greg	1.1	{
151			double dist2, safedist2, dist2cent, rad2;
152			FVECT v;
153			register SRCREC *sp;
154			int pi;
155			/* first check point location */
156			clrpart(si->spt);
157	greg	1.4	sp = source + si->sn;
158	greg	1.3	rad2 = 1.365 * DOT(sp->ss[SV],sp->ss[SV]);
159	greg	1.4	v[0] = r->rorg[0] - sp->sloc[0];
160			v[1] = r->rorg[1] - sp->sloc[1];
161			v[2] = r->rorg[2] - sp->sloc[2];
162	greg	1.1	dist2 = DOT(v,sp->ss[SU]);
163			safedist2 = DOT(sp->ss[SU],sp->ss[SU]);
164			dist2 *= dist2 / safedist2;
165			dist2cent = DOT(v,v);
166			dist2 = dist2cent - dist2;
167			if (dist2 <= rad2) { /* point inside extended cylinder */
168			si->np = 0;
169			return;
170			}
171	greg	1.4	safedist2 = 4.r->rweightr->rweight/(srcsizeratsrcsizerat);
172	greg	1.5	if (dist2 <= 4.rad2 \|\| / point too close to subdivide */
173			dist2cent >= safedist2) { /* or too far */
174	greg	1.1	setpart(si->spt, 0, S0);
175			si->np = 1;
176			return;
177			}
178			pi = 0;
179	greg	1.4	si->np = cyl_partit(r->rorg, si->spt, &pi, MAXSPART,
180	greg	1.1	sp->sloc, sp->ss[SU], safedist2);
181			}
182
183
184			static int
185			cyl_partit(ro, pt, pi, mp, cent, axis, d2) /* slice a cylinder */
186			FVECT ro;
187			unsigned char *pt;
188			register int *pi;
189			int mp;
190			FVECT cent, axis;
191			double d2;
192			{
193			FVECT newct, newax;
194			int npl, npu;
195
196			if (mp < 2 \|\| dist2(ro, cent) >= d2) { /* hit limit? */
197			setpart(pt, *pi, S0);
198			(*pi)++;
199			return(1);
200			}
201			/* subdivide */
202			setpart(pt, *pi, SU);
203			(*pi)++;
204			newax[0] = .5*axis[0];
205			newax[1] = .5*axis[1];
206			newax[2] = .5*axis[2];
207			d2 *= 0.25;
208			/* lower half */
209			newct[0] = cent[0] - newax[0];
210			newct[1] = cent[1] - newax[1];
211			newct[2] = cent[2] - newax[2];
212	greg	1.2	npl = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
213	greg	1.1	/* upper half */
214			newct[0] = cent[0] + newax[0];
215			newct[1] = cent[1] + newax[1];
216			newct[2] = cent[2] + newax[2];
217	greg	1.2	npu = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
218	greg	1.1	/* return total */
219			return(npl + npu);
220			}
221
222
223	greg	1.4	flatpart(si, r) /* partition a flat source */
224	greg	1.1	register SRCINDEX *si;
225	greg	1.5	register RAY *r;
226	greg	1.1	{
227	greg	1.6	register FLOAT *vp;
228	greg	1.5	FVECT v;
229	greg	1.1	double du2, dv2;
230			int pi;
231
232	greg	1.5	clrpart(si->spt);
233			vp = source[si->sn].sloc;
234			v[0] = r->rorg[0] - vp[0];
235			v[1] = r->rorg[1] - vp[1];
236			v[2] = r->rorg[2] - vp[2];
237			vp = source[si->sn].snorm;
238			if (DOT(v,vp) <= FTINY) { /* behind source */
239			si->np = 0;
240			return;
241			}
242	greg	1.4	dv2 = 2.*r->rweight/srcsizerat;
243			dv2 *= dv2;
244	greg	1.1	vp = source[si->sn].ss[SU];
245	greg	1.4	du2 = dv2 * DOT(vp,vp);
246	greg	1.1	vp = source[si->sn].ss[SV];
247	greg	1.4	dv2 *= DOT(vp,vp);
248	greg	1.1	pi = 0;
249	greg	1.4	si->np = flt_partit(r->rorg, si->spt, &pi, MAXSPART,
250			source[si->sn].sloc,
251	greg	1.1	source[si->sn].ss[SU], source[si->sn].ss[SV], du2, dv2);
252			}
253
254
255			static int
256			flt_partit(ro, pt, pi, mp, cent, u, v, du2, dv2) /* partition flatty */
257			FVECT ro;
258			unsigned char *pt;
259			register int *pi;
260			int mp;
261			FVECT cent, u, v;
262			double du2, dv2;
263			{
264			double d2;
265			FVECT newct, newax;
266			int npl, npu;
267
268			if (mp < 2 \|\| ((d2 = dist2(ro, cent)) >= du2
269			&& d2 >= dv2)) { /* hit limit? */
270			setpart(pt, *pi, S0);
271			(*pi)++;
272			return(1);
273			}
274			if (du2 > dv2) { /* subdivide in U */
275			setpart(pt, *pi, SU);
276			(*pi)++;
277			newax[0] = .5*u[0];
278			newax[1] = .5*u[1];
279			newax[2] = .5*u[2];
280			u = newax;
281			du2 *= 0.25;
282			} else { /* subdivide in V */
283			setpart(pt, *pi, SV);
284			(*pi)++;
285			newax[0] = .5*v[0];
286			newax[1] = .5*v[1];
287			newax[2] = .5*v[2];
288			v = newax;
289			dv2 *= 0.25;
290			}
291			/* lower half */
292			newct[0] = cent[0] - newax[0];
293			newct[1] = cent[1] - newax[1];
294			newct[2] = cent[2] - newax[2];
295	greg	1.2	npl = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
296	greg	1.1	/* upper half */
297			newct[0] = cent[0] + newax[0];
298			newct[1] = cent[1] + newax[1];
299			newct[2] = cent[2] + newax[2];
300	greg	1.2	npu = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
301	greg	1.1	/* return total */
302			return(npl + npu);
303			}
304
305
306			double
307			scylform(sn, dir) /* compute cosine for cylinder's projection */
308			int sn;
309			register FVECT dir; /* assume normalized */
310			{
311	greg	1.6	register FLOAT *dv;
312	greg	1.1	double d;
313
314			dv = source[sn].ss[SU];
315			d = DOT(dir, dv);
316			d *= d / DOT(dv,dv);
317			return(sqrt(1. - d));
318			}