src/rt/srcsamp.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 * Source sampling routines
 *
 *  External symbols declared in source.h
 */

/* ====================================================================
 * The Radiance Software License, Version 1.0
 *
 * Copyright (c) 1990 - 2002 The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory.   All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *         notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *           if any, must include the following acknowledgment:
 *             "This product includes Radiance software
 *                 (http://radsite.lbl.gov/)
 *                 developed by the Lawrence Berkeley National Laboratory
 *               (http://www.lbl.gov/)."
 *       Alternately, this acknowledgment may appear in the software itself,
 *       if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
 *       and "The Regents of the University of California" must
 *       not be used to endorse or promote products derived from this
 *       software without prior written permission. For written
 *       permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Radiance",
 *       nor may "Radiance" appear in their name, without prior written
 *       permission of Lawrence Berkeley National Laboratory.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.   IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Lawrence Berkeley National Laboratory.   For more
 * information on Lawrence Berkeley National Laboratory, please see
 * <http://www.lbl.gov/>.
 */

#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 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:	2.7
Committed:	Sat Feb 22 02:07:29 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.6:	+64 -4 lines
Log Message:	Changes and check-in for 3.5 release Includes new source files and modifications not recorded for many years See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.7	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5			* Source sampling routines
6	greg	2.7	*
7			* External symbols declared in source.h
8			*/
9
10			/* ====================================================================
11			* The Radiance Software License, Version 1.0
12			*
13			* Copyright (c) 1990 - 2002 The Regents of the University of California,
14			* through Lawrence Berkeley National Laboratory. All rights reserved.
15			*
16			* Redistribution and use in source and binary forms, with or without
17			* modification, are permitted provided that the following conditions
18			* are met:
19			*
20			* 1. Redistributions of source code must retain the above copyright
21			* notice, this list of conditions and the following disclaimer.
22			*
23			* 2. Redistributions in binary form must reproduce the above copyright
24			* notice, this list of conditions and the following disclaimer in
25			* the documentation and/or other materials provided with the
26			* distribution.
27			*
28			* 3. The end-user documentation included with the redistribution,
29			* if any, must include the following acknowledgment:
30			* "This product includes Radiance software
31			* (http://radsite.lbl.gov/)
32			* developed by the Lawrence Berkeley National Laboratory
33			* (http://www.lbl.gov/)."
34			* Alternately, this acknowledgment may appear in the software itself,
35			* if and wherever such third-party acknowledgments normally appear.
36			*
37			* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
38			* and "The Regents of the University of California" must
39			* not be used to endorse or promote products derived from this
40			* software without prior written permission. For written
41			* permission, please contact [email protected].
42			*
43			* 5. Products derived from this software may not be called "Radiance",
44			* nor may "Radiance" appear in their name, without prior written
45			* permission of Lawrence Berkeley National Laboratory.
46			*
47			* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
48			* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
49			* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
50			* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
51			* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
52			* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
53			* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
54			* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
55			* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
56			* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
57			* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58			* SUCH DAMAGE.
59			* ====================================================================
60			*
61			* This software consists of voluntary contributions made by many
62			* individuals on behalf of Lawrence Berkeley National Laboratory. For more
63			* information on Lawrence Berkeley National Laboratory, please see
64			* <http://www.lbl.gov/>.
65	greg	1.1	*/
66
67	greg	1.4	#include "ray.h"
68	greg	1.1
69			#include "source.h"
70
71			#include "random.h"
72
73
74	greg	2.5	static int cyl_partit(), flt_partit();
75
76
77	greg	1.1	double
78	greg	1.4	nextssamp(r, si) /* compute sample for source, rtn. distance */
79			register RAY r; / origin is read, direction is set */
80	greg	1.1	register SRCINDEX si; / source index (modified to current) */
81			{
82			int cent[3], size[3], parr[2];
83			FVECT vpos;
84			double d;
85			register int i;
86	greg	2.2	nextsample:
87	greg	1.1	while (++si->sp >= si->np) { /* get next sample */
88			if (++si->sn >= nsources)
89			return(0.0); /* no more */
90	greg	1.7	if (source[si->sn].sflags & SSKIP)
91			si->np = 0;
92			else if (srcsizerat <= FTINY)
93	greg	1.4	nopart(si, r);
94	greg	1.1	else {
95			for (i = si->sn; source[i].sflags & SVIRTUAL;
96			i = source[i].sa.sv.sn)
97			; /* partition source */
98	greg	1.4	(*sfun[source[i].so->otype].of->partit)(si, r);
99	greg	1.1	}
100			si->sp = -1;
101			}
102			/* get partition */
103			cent[0] = cent[1] = cent[2] = 0;
104			size[0] = size[1] = size[2] = MAXSPART;
105			parr[0] = 0; parr[1] = si->sp;
106			if (!skipparts(cent, size, parr, si->spt))
107			error(CONSISTENCY, "bad source partition in nextssamp");
108			/* compute sample */
109			if (dstrsrc > FTINY) { /* jitter sample */
110			dimlist[ndims] = si->sn + 8831;
111			dimlist[ndims+1] = si->sp + 3109;
112			d = urand(ilhash(dimlist,ndims+2)+samplendx);
113			if (source[si->sn].sflags & SFLAT) {
114			multisamp(vpos, 2, d);
115			vpos[2] = 0.5;
116			} else
117			multisamp(vpos, 3, d);
118			for (i = 0; i < 3; i++)
119			vpos[i] = dstrsrc * (1. - 2.vpos[i])
120			(double)size[i]/MAXSPART;
121			} else
122			vpos[0] = vpos[1] = vpos[2] = 0.0;
123
124			for (i = 0; i < 3; i++)
125			vpos[i] += (double)cent[i]/MAXSPART;
126			/* compute direction */
127			for (i = 0; i < 3; i++)
128	greg	1.4	r->rdir[i] = source[si->sn].sloc[i] +
129	greg	1.1	vpos[SU]*source[si->sn].ss[SU][i] +
130			vpos[SV]*source[si->sn].ss[SV][i] +
131			vpos[SW]*source[si->sn].ss[SW][i];
132
133			if (!(source[si->sn].sflags & SDISTANT))
134			for (i = 0; i < 3; i++)
135	greg	1.4	r->rdir[i] -= r->rorg[i];
136	greg	1.1	/* compute distance */
137	greg	1.4	if ((d = normalize(r->rdir)) == 0.0)
138	greg	2.2	goto nextsample; /* at source! */
139	greg	1.1
140			/* compute sample size */
141			if (source[si->sn].sflags & SFLAT) {
142	greg	2.6	si->dom = sflatform(si->sn, r->rdir);
143	greg	2.4	si->dom = size[SU]size[SV]/(MAXSPART*(double)MAXSPART);
144	greg	1.1	} else if (source[si->sn].sflags & SCYL) {
145	greg	2.6	si->dom = scylform(si->sn, r->rdir);
146	greg	2.4	si->dom *= size[SU]/(double)MAXSPART;
147	greg	1.1	} else {
148	greg	2.6	si->dom = size[SU]size[SV](double)size[SW] /
149	greg	2.4	(MAXSPARTMAXSPART(double)MAXSPART) ;
150	greg	1.1	}
151	greg	2.6	if (source[si->sn].sflags & SDISTANT) {
152			si->dom *= source[si->sn].ss2;
153	greg	1.1	return(FHUGE);
154	greg	2.6	}
155	greg	2.3	if (si->dom <= 1e-4)
156	greg	2.2	goto nextsample; /* behind source? */
157	greg	2.6	si->dom = source[si->sn].ss2/(dd);
158	greg	1.1	return(d); /* sample OK, return distance */
159			}
160
161
162	greg	2.7	int
163	greg	1.1	skipparts(ct, sz, pp, pt) /* skip to requested partition */
164			int ct[3], sz[3]; /* center and size of partition (returned) */
165			register int pp[2]; /* current index, number to skip (modified) */
166			unsigned char pt; / partition array */
167			{
168			register int p;
169			/* check this partition */
170			p = spart(pt, pp[0]);
171			pp[0]++;
172			if (p == S0) /* leaf partition */
173			if (pp[1]) {
174			pp[1]--;
175			return(0); /* not there yet */
176			} else
177			return(1); /* we've arrived */
178			/* else check lower */
179			sz[p] >>= 1;
180			ct[p] -= sz[p];
181			if (skipparts(ct, sz, pp, pt))
182			return(1); /* return hit */
183			/* else check upper */
184			ct[p] += sz[p] << 1;
185			if (skipparts(ct, sz, pp, pt))
186			return(1); /* return hit */
187			/* else return to starting position */
188			ct[p] -= sz[p];
189			sz[p] <<= 1;
190			return(0); /* return miss */
191			}
192
193
194	greg	2.7	void
195	greg	1.4	nopart(si, r) /* single source partition */
196	greg	1.1	register SRCINDEX *si;
197	greg	1.4	RAY *r;
198	greg	1.1	{
199			clrpart(si->spt);
200			setpart(si->spt, 0, S0);
201			si->np = 1;
202			}
203
204
205	greg	2.7	void
206	greg	1.4	cylpart(si, r) /* partition a cylinder */
207	greg	1.1	SRCINDEX *si;
208	greg	1.4	register RAY *r;
209	greg	1.1	{
210			double dist2, safedist2, dist2cent, rad2;
211			FVECT v;
212			register SRCREC *sp;
213			int pi;
214			/* first check point location */
215			clrpart(si->spt);
216	greg	1.4	sp = source + si->sn;
217	greg	1.3	rad2 = 1.365 * DOT(sp->ss[SV],sp->ss[SV]);
218	greg	1.4	v[0] = r->rorg[0] - sp->sloc[0];
219			v[1] = r->rorg[1] - sp->sloc[1];
220			v[2] = r->rorg[2] - sp->sloc[2];
221	greg	1.1	dist2 = DOT(v,sp->ss[SU]);
222			safedist2 = DOT(sp->ss[SU],sp->ss[SU]);
223			dist2 *= dist2 / safedist2;
224			dist2cent = DOT(v,v);
225			dist2 = dist2cent - dist2;
226			if (dist2 <= rad2) { /* point inside extended cylinder */
227			si->np = 0;
228			return;
229			}
230	greg	1.4	safedist2 = 4.r->rweightr->rweight/(srcsizeratsrcsizerat);
231	greg	1.5	if (dist2 <= 4.rad2 \|\| / point too close to subdivide */
232			dist2cent >= safedist2) { /* or too far */
233	greg	1.1	setpart(si->spt, 0, S0);
234			si->np = 1;
235			return;
236			}
237			pi = 0;
238	greg	1.4	si->np = cyl_partit(r->rorg, si->spt, &pi, MAXSPART,
239	greg	1.1	sp->sloc, sp->ss[SU], safedist2);
240			}
241
242
243			static int
244			cyl_partit(ro, pt, pi, mp, cent, axis, d2) /* slice a cylinder */
245			FVECT ro;
246			unsigned char *pt;
247			register int *pi;
248			int mp;
249			FVECT cent, axis;
250			double d2;
251			{
252			FVECT newct, newax;
253			int npl, npu;
254
255			if (mp < 2 \|\| dist2(ro, cent) >= d2) { /* hit limit? */
256			setpart(pt, *pi, S0);
257			(*pi)++;
258			return(1);
259			}
260			/* subdivide */
261			setpart(pt, *pi, SU);
262			(*pi)++;
263			newax[0] = .5*axis[0];
264			newax[1] = .5*axis[1];
265			newax[2] = .5*axis[2];
266			d2 *= 0.25;
267			/* lower half */
268			newct[0] = cent[0] - newax[0];
269			newct[1] = cent[1] - newax[1];
270			newct[2] = cent[2] - newax[2];
271	greg	1.2	npl = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
272	greg	1.1	/* upper half */
273			newct[0] = cent[0] + newax[0];
274			newct[1] = cent[1] + newax[1];
275			newct[2] = cent[2] + newax[2];
276	greg	1.2	npu = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
277	greg	1.1	/* return total */
278			return(npl + npu);
279			}
280
281
282	greg	2.7	void
283	greg	1.4	flatpart(si, r) /* partition a flat source */
284	greg	1.1	register SRCINDEX *si;
285	greg	1.5	register RAY *r;
286	greg	1.1	{
287	greg	1.6	register FLOAT *vp;
288	greg	1.5	FVECT v;
289	greg	1.1	double du2, dv2;
290			int pi;
291
292	greg	1.5	clrpart(si->spt);
293			vp = source[si->sn].sloc;
294			v[0] = r->rorg[0] - vp[0];
295			v[1] = r->rorg[1] - vp[1];
296			v[2] = r->rorg[2] - vp[2];
297			vp = source[si->sn].snorm;
298			if (DOT(v,vp) <= FTINY) { /* behind source */
299			si->np = 0;
300			return;
301			}
302	greg	1.4	dv2 = 2.*r->rweight/srcsizerat;
303			dv2 *= dv2;
304	greg	1.1	vp = source[si->sn].ss[SU];
305	greg	1.4	du2 = dv2 * DOT(vp,vp);
306	greg	1.1	vp = source[si->sn].ss[SV];
307	greg	1.4	dv2 *= DOT(vp,vp);
308	greg	1.1	pi = 0;
309	greg	1.4	si->np = flt_partit(r->rorg, si->spt, &pi, MAXSPART,
310			source[si->sn].sloc,
311	greg	1.1	source[si->sn].ss[SU], source[si->sn].ss[SV], du2, dv2);
312			}
313
314
315			static int
316			flt_partit(ro, pt, pi, mp, cent, u, v, du2, dv2) /* partition flatty */
317			FVECT ro;
318			unsigned char *pt;
319			register int *pi;
320			int mp;
321			FVECT cent, u, v;
322			double du2, dv2;
323			{
324			double d2;
325			FVECT newct, newax;
326			int npl, npu;
327
328			if (mp < 2 \|\| ((d2 = dist2(ro, cent)) >= du2
329			&& d2 >= dv2)) { /* hit limit? */
330			setpart(pt, *pi, S0);
331			(*pi)++;
332			return(1);
333			}
334			if (du2 > dv2) { /* subdivide in U */
335			setpart(pt, *pi, SU);
336			(*pi)++;
337			newax[0] = .5*u[0];
338			newax[1] = .5*u[1];
339			newax[2] = .5*u[2];
340			u = newax;
341			du2 *= 0.25;
342			} else { /* subdivide in V */
343			setpart(pt, *pi, SV);
344			(*pi)++;
345			newax[0] = .5*v[0];
346			newax[1] = .5*v[1];
347			newax[2] = .5*v[2];
348			v = newax;
349			dv2 *= 0.25;
350			}
351			/* lower half */
352			newct[0] = cent[0] - newax[0];
353			newct[1] = cent[1] - newax[1];
354			newct[2] = cent[2] - newax[2];
355	greg	1.2	npl = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
356	greg	1.1	/* upper half */
357			newct[0] = cent[0] + newax[0];
358			newct[1] = cent[1] + newax[1];
359			newct[2] = cent[2] + newax[2];
360	greg	1.2	npu = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
361	greg	1.1	/* return total */
362			return(npl + npu);
363			}
364
365
366			double
367			scylform(sn, dir) /* compute cosine for cylinder's projection */
368			int sn;
369			register FVECT dir; /* assume normalized */
370			{
371	greg	1.6	register FLOAT *dv;
372	greg	1.1	double d;
373
374			dv = source[sn].ss[SU];
375			d = DOT(dir, dv);
376			d *= d / DOT(dv,dv);
377			return(sqrt(1. - d));
378			}