src/rt/srcsamp.c

#ifndef lint
static const char       RCSid[] = "$Id: srcsamp.c,v 2.10 2003/07/21 22:30:19 schorsch Exp $";
#endif
/*
 * Source sampling routines
 *
 *  External symbols declared in source.h
 */

#include "copyright.h"

#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 */
}


int
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 */
}


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


void
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);
}


void
flatpart(si, r)                         /* partition a flat source */
register SRCINDEX  *si;
register RAY  *r;
{
        register RREAL  *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) <= 0.) {          /* 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 RREAL  *dv;
        double  d;

        dv = source[sn].ss[SU];
        d = DOT(dir, dv);
        d *= d / DOT(dv,dv);
        return(sqrt(1. - d));
}
Revision:	2.11
Committed:	Sat Sep 13 17:31:35 2003 UTC (20 years, 7 months ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R7P2, rad3R7P1, rad3R6, rad3R6P1, rad3R8, rad3R9
Changes since 2.10:	+2 -2 lines
Log Message:	Minor fix in source sampling calculation
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.11	static const char RCSid[] = "$Id: srcsamp.c,v 2.10 2003/07/21 22:30:19 schorsch Exp $";
3	greg	1.1	#endif
4			/*
5			* Source sampling routines
6	greg	2.7	*
7			* External symbols declared in source.h
8			*/
9
10	greg	2.8	#include "copyright.h"
11	greg	1.1
12	greg	1.4	#include "ray.h"
13	greg	1.1
14			#include "source.h"
15
16			#include "random.h"
17
18
19	greg	2.5	static int cyl_partit(), flt_partit();
20
21
22	greg	1.1	double
23	greg	1.4	nextssamp(r, si) /* compute sample for source, rtn. distance */
24			register RAY r; / origin is read, direction is set */
25	greg	1.1	register SRCINDEX si; / source index (modified to current) */
26			{
27			int cent[3], size[3], parr[2];
28			FVECT vpos;
29			double d;
30			register int i;
31	greg	2.2	nextsample:
32	greg	1.1	while (++si->sp >= si->np) { /* get next sample */
33			if (++si->sn >= nsources)
34			return(0.0); /* no more */
35	greg	1.7	if (source[si->sn].sflags & SSKIP)
36			si->np = 0;
37			else if (srcsizerat <= FTINY)
38	greg	1.4	nopart(si, r);
39	greg	1.1	else {
40			for (i = si->sn; source[i].sflags & SVIRTUAL;
41			i = source[i].sa.sv.sn)
42			; /* partition source */
43	greg	1.4	(*sfun[source[i].so->otype].of->partit)(si, r);
44	greg	1.1	}
45			si->sp = -1;
46			}
47			/* get partition */
48			cent[0] = cent[1] = cent[2] = 0;
49			size[0] = size[1] = size[2] = MAXSPART;
50			parr[0] = 0; parr[1] = si->sp;
51			if (!skipparts(cent, size, parr, si->spt))
52			error(CONSISTENCY, "bad source partition in nextssamp");
53			/* compute sample */
54			if (dstrsrc > FTINY) { /* jitter sample */
55			dimlist[ndims] = si->sn + 8831;
56			dimlist[ndims+1] = si->sp + 3109;
57			d = urand(ilhash(dimlist,ndims+2)+samplendx);
58			if (source[si->sn].sflags & SFLAT) {
59			multisamp(vpos, 2, d);
60			vpos[2] = 0.5;
61			} else
62			multisamp(vpos, 3, d);
63			for (i = 0; i < 3; i++)
64			vpos[i] = dstrsrc * (1. - 2.vpos[i])
65			(double)size[i]/MAXSPART;
66			} else
67			vpos[0] = vpos[1] = vpos[2] = 0.0;
68
69			for (i = 0; i < 3; i++)
70			vpos[i] += (double)cent[i]/MAXSPART;
71			/* compute direction */
72			for (i = 0; i < 3; i++)
73	greg	1.4	r->rdir[i] = source[si->sn].sloc[i] +
74	greg	1.1	vpos[SU]*source[si->sn].ss[SU][i] +
75			vpos[SV]*source[si->sn].ss[SV][i] +
76			vpos[SW]*source[si->sn].ss[SW][i];
77
78			if (!(source[si->sn].sflags & SDISTANT))
79			for (i = 0; i < 3; i++)
80	greg	1.4	r->rdir[i] -= r->rorg[i];
81	greg	1.1	/* compute distance */
82	greg	1.4	if ((d = normalize(r->rdir)) == 0.0)
83	greg	2.2	goto nextsample; /* at source! */
84	greg	1.1
85			/* compute sample size */
86			if (source[si->sn].sflags & SFLAT) {
87	greg	2.6	si->dom = sflatform(si->sn, r->rdir);
88	greg	2.4	si->dom = size[SU]size[SV]/(MAXSPART*(double)MAXSPART);
89	greg	1.1	} else if (source[si->sn].sflags & SCYL) {
90	greg	2.6	si->dom = scylform(si->sn, r->rdir);
91	greg	2.4	si->dom *= size[SU]/(double)MAXSPART;
92	greg	1.1	} else {
93	greg	2.6	si->dom = size[SU]size[SV](double)size[SW] /
94	greg	2.4	(MAXSPARTMAXSPART(double)MAXSPART) ;
95	greg	1.1	}
96	greg	2.6	if (source[si->sn].sflags & SDISTANT) {
97			si->dom *= source[si->sn].ss2;
98	greg	1.1	return(FHUGE);
99	greg	2.6	}
100	greg	2.3	if (si->dom <= 1e-4)
101	greg	2.2	goto nextsample; /* behind source? */
102	greg	2.6	si->dom = source[si->sn].ss2/(dd);
103	greg	1.1	return(d); /* sample OK, return distance */
104			}
105
106
107	greg	2.7	int
108	greg	1.1	skipparts(ct, sz, pp, pt) /* skip to requested partition */
109			int ct[3], sz[3]; /* center and size of partition (returned) */
110			register int pp[2]; /* current index, number to skip (modified) */
111			unsigned char pt; / partition array */
112			{
113			register int p;
114			/* check this partition */
115			p = spart(pt, pp[0]);
116			pp[0]++;
117	schorsch	2.10	if (p == S0) { /* leaf partition */
118	greg	1.1	if (pp[1]) {
119			pp[1]--;
120			return(0); /* not there yet */
121			} else
122			return(1); /* we've arrived */
123	schorsch	2.10	}
124	greg	1.1	/* else check lower */
125			sz[p] >>= 1;
126			ct[p] -= sz[p];
127			if (skipparts(ct, sz, pp, pt))
128			return(1); /* return hit */
129			/* else check upper */
130			ct[p] += sz[p] << 1;
131			if (skipparts(ct, sz, pp, pt))
132			return(1); /* return hit */
133			/* else return to starting position */
134			ct[p] -= sz[p];
135			sz[p] <<= 1;
136			return(0); /* return miss */
137			}
138
139
140	greg	2.7	void
141	greg	1.4	nopart(si, r) /* single source partition */
142	greg	1.1	register SRCINDEX *si;
143	greg	1.4	RAY *r;
144	greg	1.1	{
145			clrpart(si->spt);
146			setpart(si->spt, 0, S0);
147			si->np = 1;
148			}
149
150
151	greg	2.7	void
152	greg	1.4	cylpart(si, r) /* partition a cylinder */
153	greg	1.1	SRCINDEX *si;
154	greg	1.4	register RAY *r;
155	greg	1.1	{
156			double dist2, safedist2, dist2cent, rad2;
157			FVECT v;
158			register SRCREC *sp;
159			int pi;
160			/* first check point location */
161			clrpart(si->spt);
162	greg	1.4	sp = source + si->sn;
163	greg	1.3	rad2 = 1.365 * DOT(sp->ss[SV],sp->ss[SV]);
164	greg	1.4	v[0] = r->rorg[0] - sp->sloc[0];
165			v[1] = r->rorg[1] - sp->sloc[1];
166			v[2] = r->rorg[2] - sp->sloc[2];
167	greg	1.1	dist2 = DOT(v,sp->ss[SU]);
168			safedist2 = DOT(sp->ss[SU],sp->ss[SU]);
169			dist2 *= dist2 / safedist2;
170			dist2cent = DOT(v,v);
171			dist2 = dist2cent - dist2;
172			if (dist2 <= rad2) { /* point inside extended cylinder */
173			si->np = 0;
174			return;
175			}
176	greg	1.4	safedist2 = 4.r->rweightr->rweight/(srcsizeratsrcsizerat);
177	greg	1.5	if (dist2 <= 4.rad2 \|\| / point too close to subdivide */
178			dist2cent >= safedist2) { /* or too far */
179	greg	1.1	setpart(si->spt, 0, S0);
180			si->np = 1;
181			return;
182			}
183			pi = 0;
184	greg	1.4	si->np = cyl_partit(r->rorg, si->spt, &pi, MAXSPART,
185	greg	1.1	sp->sloc, sp->ss[SU], safedist2);
186			}
187
188
189			static int
190			cyl_partit(ro, pt, pi, mp, cent, axis, d2) /* slice a cylinder */
191			FVECT ro;
192			unsigned char *pt;
193			register int *pi;
194			int mp;
195			FVECT cent, axis;
196			double d2;
197			{
198			FVECT newct, newax;
199			int npl, npu;
200
201			if (mp < 2 \|\| dist2(ro, cent) >= d2) { /* hit limit? */
202			setpart(pt, *pi, S0);
203			(*pi)++;
204			return(1);
205			}
206			/* subdivide */
207			setpart(pt, *pi, SU);
208			(*pi)++;
209			newax[0] = .5*axis[0];
210			newax[1] = .5*axis[1];
211			newax[2] = .5*axis[2];
212			d2 *= 0.25;
213			/* lower 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	npl = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
218	greg	1.1	/* upper half */
219			newct[0] = cent[0] + newax[0];
220			newct[1] = cent[1] + newax[1];
221			newct[2] = cent[2] + newax[2];
222	greg	1.2	npu = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
223	greg	1.1	/* return total */
224			return(npl + npu);
225			}
226
227
228	greg	2.7	void
229	greg	1.4	flatpart(si, r) /* partition a flat source */
230	greg	1.1	register SRCINDEX *si;
231	greg	1.5	register RAY *r;
232	greg	1.1	{
233	schorsch	2.9	register RREAL *vp;
234	greg	1.5	FVECT v;
235	greg	1.1	double du2, dv2;
236			int pi;
237
238	greg	1.5	clrpart(si->spt);
239			vp = source[si->sn].sloc;
240			v[0] = r->rorg[0] - vp[0];
241			v[1] = r->rorg[1] - vp[1];
242			v[2] = r->rorg[2] - vp[2];
243			vp = source[si->sn].snorm;
244	greg	2.11	if (DOT(v,vp) <= 0.) { /* behind source */
245	greg	1.5	si->np = 0;
246			return;
247			}
248	greg	1.4	dv2 = 2.*r->rweight/srcsizerat;
249			dv2 *= dv2;
250	greg	1.1	vp = source[si->sn].ss[SU];
251	greg	1.4	du2 = dv2 * DOT(vp,vp);
252	greg	1.1	vp = source[si->sn].ss[SV];
253	greg	1.4	dv2 *= DOT(vp,vp);
254	greg	1.1	pi = 0;
255	greg	1.4	si->np = flt_partit(r->rorg, si->spt, &pi, MAXSPART,
256			source[si->sn].sloc,
257	greg	1.1	source[si->sn].ss[SU], source[si->sn].ss[SV], du2, dv2);
258			}
259
260
261			static int
262			flt_partit(ro, pt, pi, mp, cent, u, v, du2, dv2) /* partition flatty */
263			FVECT ro;
264			unsigned char *pt;
265			register int *pi;
266			int mp;
267			FVECT cent, u, v;
268			double du2, dv2;
269			{
270			double d2;
271			FVECT newct, newax;
272			int npl, npu;
273
274			if (mp < 2 \|\| ((d2 = dist2(ro, cent)) >= du2
275			&& d2 >= dv2)) { /* hit limit? */
276			setpart(pt, *pi, S0);
277			(*pi)++;
278			return(1);
279			}
280			if (du2 > dv2) { /* subdivide in U */
281			setpart(pt, *pi, SU);
282			(*pi)++;
283			newax[0] = .5*u[0];
284			newax[1] = .5*u[1];
285			newax[2] = .5*u[2];
286			u = newax;
287			du2 *= 0.25;
288			} else { /* subdivide in V */
289			setpart(pt, *pi, SV);
290			(*pi)++;
291			newax[0] = .5*v[0];
292			newax[1] = .5*v[1];
293			newax[2] = .5*v[2];
294			v = newax;
295			dv2 *= 0.25;
296			}
297			/* lower half */
298			newct[0] = cent[0] - newax[0];
299			newct[1] = cent[1] - newax[1];
300			newct[2] = cent[2] - newax[2];
301	greg	1.2	npl = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
302	greg	1.1	/* upper half */
303			newct[0] = cent[0] + newax[0];
304			newct[1] = cent[1] + newax[1];
305			newct[2] = cent[2] + newax[2];
306	greg	1.2	npu = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
307	greg	1.1	/* return total */
308			return(npl + npu);
309			}
310
311
312			double
313			scylform(sn, dir) /* compute cosine for cylinder's projection */
314			int sn;
315			register FVECT dir; /* assume normalized */
316			{
317	schorsch	2.9	register RREAL *dv;
318	greg	1.1	double d;
319
320			dv = source[sn].ss[SU];
321			d = DOT(dir, dv);
322			d *= d / DOT(dv,dv);
323			return(sqrt(1. - d));
324			}