src/rt/srcsamp.c

#ifndef lint
static const char       RCSid[] = "$Id: srcsamp.c,v 2.23 2024/12/13 00:50:55 greg Exp $";
#endif
/*
 * Source sampling routines
 *
 *  External symbols declared in source.h
 */

#include "copyright.h"

#include  "ray.h"

#include  "source.h"

#include  "random.h"

#ifdef SSKIPOPT
/* The following table is used for skipping sources */
static uby8     *srcskipflags = NULL;           /* source inclusion lookup */
static int      ssf_count = 0;                  /* number of flag entries */
static int      ssf_max = 0;                    /* current array size */
static uby8     *ssf_noskip = NULL;             /* set of zero flags */

uby8            *ssf_select = NULL;             /* sources we may skip */

/* Find/allocate source skip flag entry (free all if NULL) */
int
sskip_rsi(uby8 *flags)
{
        uby8    *flp;
        int     i;

        if (flags == NULL) {            /* means clear all */
                efree(srcskipflags); srcskipflags = NULL;
                ssf_count = ssf_max = 0;
                sskip_free(ssf_noskip);
                sskip_free(ssf_select);
                return(0);
        }
        if (ssf_noskip == NULL)         /* first call? */
                ssf_noskip = sskip_new();

        if (sskip_eq(flags, ssf_noskip))
                return(-1);             /* nothing to skip */
                                        /* search recent entries */
        flp = srcskipflags + ssf_count*SSKIPFLSIZ;
        for (i = ssf_count; i-- > 0; )
                if (sskip_eq(flp -= SSKIPFLSIZ, flags))
                        return(-2-i);   /* found it! */
                                        /* else tack on new entry */
        if (ssf_count >= ssf_max) {     /* need more space? */
                ssf_max = ssf_count + (ssf_count>>2) + 64;
                if (ssf_max <= ssf_count &&
                                (ssf_max = ssf_count+1024) <= ssf_count)
                        error(SYSTEM, "out of space in sskip_rsi()");

                srcskipflags = (uby8 *)erealloc(srcskipflags,
                                                ssf_max*SSKIPFLSIZ);
        }
        sskip_cpy(srcskipflags + ssf_count*SSKIPFLSIZ, flags);

        return(-2 - ssf_count++);       /* return index (< -1) */
}

/* Get skip flags associated with RAY rsrc index (or NULL) */
uby8 *
sskip_flags(int rsi)
{
        if (rsi >= -1)
                return(ssf_noskip);

        if ((rsi = -2 - rsi) >= ssf_count)
                error(CONSISTENCY, "bad index to sskip_flags()");

        return(srcskipflags + rsi*SSKIPFLSIZ);
}

/* OR in a second set of flags into a first */
void
sskip_addflags(uby8 *dfl, const uby8 *sfl)
{
        int     nb = SSKIPFLSIZ;

        while (nb--)
                *dfl++ |= *sfl++;
}
#endif

int
srcskip(                        /* pre-emptive test for source to skip */
        int  sn,
        RAY  *r
)
{
        SRCREC  *sp = source + sn;

        if (sp->sflags & SSKIP)
                return(1);
#ifdef SSKIPOPT                 /* parent ray has custom skip flags? */
        if (r->parent != NULL && r->parent->rsrc < -1 &&
                        sskip_chk(sskip_flags(r->parent->rsrc), sn))
                return(1);
#endif
        if ((sp->sflags & (SPROX|SDISTANT)) == SPROX)
                return(dist2(r->rorg, sp->sloc) >
                        (sp->sl.prox + sp->srad)*(sp->sl.prox + sp->srad));
        return(0);
}

double
nextssamp(                      /* compute sample for source, rtn. distance */
        RAY  *r,                /* origin is read, direction is set */
        SRCINDEX  *si           /* source index (modified to current) */
)
{
        int  cent[3], size[3], parr[2];
        SRCREC  *srcp;
        double  vpos[3];
        double  d;
        int  i;
nextsample:
        while (++si->sp >= si->np) {    /* get next sample */
                if (++si->sn >= nsources)
                        return(0.0);    /* no more */
                if (srcskip(si->sn, r))
                        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 */
        srcp = source + si->sn;
        if (dstrsrc > FTINY) {                  /* jitter sample */
                dimlist[ndims] = si->sn + 8831;
                dimlist[ndims+1] = si->sp + 3109;
                d = urand(ilhash(dimlist,ndims+2)+samplendx);
                if (srcp->sflags & SFLAT) {
                        multisamp(vpos, 2, d);
                        vpos[SW] = 0.5;
                } else
                        multisamp(vpos, 3, d);
                for (i = 0; i < 3; i++)
                        vpos[i] = dstrsrc * (1. - 2.*vpos[i]) *
                                        (double)size[i]*(1.0/MAXSPART);
        } else
                vpos[0] = vpos[1] = vpos[2] = 0.0;

        VSUM(vpos, vpos, cent, 1.0/MAXSPART);
                                        /* avoid circular aiming failures */
        if ((srcp->sflags & SCIR) && (si->np > 1) | (dstrsrc > 0.7)) {
                FVECT   trim;
                if (srcp->sflags & (SFLAT|SDISTANT)) {
                        d = 1.12837917;         /* correct setflatss() */
                        trim[SU] = d*sqrt(1.0 - 0.5*vpos[SV]*vpos[SV]);
                        trim[SV] = d*sqrt(1.0 - 0.5*vpos[SU]*vpos[SU]);
                        trim[SW] = 0.0;
                } else {
                        trim[SW] = trim[SU] = vpos[SU]*vpos[SU];
                        d = vpos[SV]*vpos[SV];
                        if (d > trim[SW]) trim[SW] = d;
                        trim[SU] += d;
                        d = vpos[SW]*vpos[SW];
                        if (d > trim[SW]) trim[SW] = d;
                        trim[SU] += d;
                        if (trim[SU] > FTINY*FTINY) {
                                d = 1.0/0.7236; /* correct sphsetsrc() */
                                trim[SW] = trim[SV] = trim[SU] =
                                                d*sqrt(trim[SW]/trim[SU]);
                        } else
                                trim[SW] = trim[SV] = trim[SU] = 0.0;
                }
                for (i = 0; i < 3; i++)
                        vpos[i] *= trim[i];
        }
                                        /* compute direction */
        for (i = 0; i < 3; i++)
                r->rdir[i] = srcp->sloc[i] +
                                vpos[SU]*srcp->ss[SU][i] +
                                vpos[SV]*srcp->ss[SV][i] +
                                vpos[SW]*srcp->ss[SW][i];

        if (!(srcp->sflags & SDISTANT))
                VSUB(r->rdir, r->rdir, r->rorg);
                                        /* compute distance */
        if ((d = normalize(r->rdir)) == 0.0)
                goto nextsample;                /* at source! */

                                        /* compute sample size */
        if (srcp->sflags & SFLAT) {
                si->dom = sflatform(si->sn, r->rdir);
                si->dom *= size[SU]*size[SV]*(1.0/MAXSPART/MAXSPART);
        } else if (srcp->sflags & SCYL) {
                si->dom = scylform(si->sn, r->rdir);
                si->dom *= size[SU]*(1.0/MAXSPART);
        } else {
                si->dom = size[SU]*size[SV]*(double)size[SW] *
                                (1.0/MAXSPART/MAXSPART/MAXSPART) ;
        }
        if (srcp->sflags & SDISTANT) {
                si->dom *= srcp->ss2;
                return(FHUGE);
        }
        if (si->dom <= 1e-4)
                goto nextsample;                /* behind source? */
        si->dom *= srcp->ss2/(d*d);
        return(d);              /* sample OK, return distance */
}


int
skipparts(                      /* skip to requested partition */
        int  ct[3],
        int  sz[3],             /* center and size of partition (returned) */
        int  pp[2],             /* current index, number to skip (modified) */
        unsigned char  *pt      /* partition array */
)
{
        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(                         /* single source partition */
        SRCINDEX  *si,
        RAY  *r
)
{
        clrpart(si->spt);
        setpart(si->spt, 0, S0);
        si->np = 1;
}


static int
cyl_partit(                             /* slice a cylinder */
        FVECT  ro,
        unsigned char  *pt,
        int  *pi,
        int  mp,
        FVECT  cent,
        FVECT  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
cylpart(                        /* partition a cylinder */
        SRCINDEX  *si,
        RAY  *r
)
{
        double  dist2, safedist2, dist2cent, rad2;
        FVECT  v;
        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
flt_partit(                             /* partition flatty */
        FVECT  ro,
        unsigned char  *pt,
        int  *pi,
        int  mp,
        FVECT  cent,
        FVECT  u,
        FVECT  v,
        double  du2,
        double  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);
}


void
flatpart(                               /* partition a flat source */
        SRCINDEX  *si,
        RAY  *r
)
{
        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);
}


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

        dv = source[sn].ss[SU];
        d = DOT(dir, dv);
        d *= d / DOT(dv,dv);
        return(sqrt(1. - d));
}
Revision:	2.24
Committed:	Wed Dec 25 17:40:27 2024 UTC (4 months, 3 weeks ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.23:	+7 -8 lines
Log Message:	fix: Corrections to source skip test, mostly for SSKIPOPT option
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.24	static const char RCSid[] = "$Id: srcsamp.c,v 2.23 2024/12/13 00:50:55 greg 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	greg	2.22	#ifdef SSKIPOPT
19			/* The following table is used for skipping sources */
20			static uby8 srcskipflags = NULL; / source inclusion lookup */
21			static int ssf_count = 0; /* number of flag entries */
22			static int ssf_max = 0; /* current array size */
23			static uby8 ssf_noskip = NULL; / set of zero flags */
24
25			uby8 ssf_select = NULL; / sources we may skip */
26
27			/* Find/allocate source skip flag entry (free all if NULL) */
28			int
29			sskip_rsi(uby8 *flags)
30			{
31			uby8 *flp;
32			int i;
33
34			if (flags == NULL) { /* means clear all */
35			efree(srcskipflags); srcskipflags = NULL;
36			ssf_count = ssf_max = 0;
37			sskip_free(ssf_noskip);
38			sskip_free(ssf_select);
39			return(0);
40			}
41			if (ssf_noskip == NULL) /* first call? */
42			ssf_noskip = sskip_new();
43
44			if (sskip_eq(flags, ssf_noskip))
45			return(-1); /* nothing to skip */
46			/* search recent entries */
47			flp = srcskipflags + ssf_count*SSKIPFLSIZ;
48			for (i = ssf_count; i-- > 0; )
49			if (sskip_eq(flp -= SSKIPFLSIZ, flags))
50			return(-2-i); /* found it! */
51			/* else tack on new entry */
52			if (ssf_count >= ssf_max) { /* need more space? */
53			ssf_max = ssf_count + (ssf_count>>2) + 64;
54			if (ssf_max <= ssf_count &&
55			(ssf_max = ssf_count+1024) <= ssf_count)
56			error(SYSTEM, "out of space in sskip_rsi()");
57
58			srcskipflags = (uby8 *)erealloc(srcskipflags,
59			ssf_max*SSKIPFLSIZ);
60			}
61			sskip_cpy(srcskipflags + ssf_count*SSKIPFLSIZ, flags);
62
63			return(-2 - ssf_count++); /* return index (< -1) */
64			}
65
66			/* Get skip flags associated with RAY rsrc index (or NULL) */
67			uby8 *
68			sskip_flags(int rsi)
69			{
70			if (rsi >= -1)
71			return(ssf_noskip);
72
73			if ((rsi = -2 - rsi) >= ssf_count)
74			error(CONSISTENCY, "bad index to sskip_flags()");
75
76			return(srcskipflags + rsi*SSKIPFLSIZ);
77			}
78
79			/* OR in a second set of flags into a first */
80			void
81			sskip_addflags(uby8 dfl, const uby8 sfl)
82			{
83			int nb = SSKIPFLSIZ;
84
85			while (nb--)
86			dfl++ \|= sfl++;
87			}
88			#endif
89	greg	1.1
90	greg	2.21	int
91			srcskip( /* pre-emptive test for source to skip */
92			int sn,
93			RAY *r
94	greg	2.18	)
95			{
96	greg	2.21	SRCREC *sp = source + sn;
97
98	greg	2.18	if (sp->sflags & SSKIP)
99			return(1);
100	greg	2.24	#ifdef SSKIPOPT /* parent ray has custom skip flags? */
101			if (r->parent != NULL && r->parent->rsrc < -1 &&
102			sskip_chk(sskip_flags(r->parent->rsrc), sn))
103	greg	2.22	return(1);
104			#endif
105	greg	2.24	if ((sp->sflags & (SPROX\|SDISTANT)) == SPROX)
106			return(dist2(r->rorg, sp->sloc) >
107	greg	2.18	(sp->sl.prox + sp->srad)*(sp->sl.prox + sp->srad));
108	greg	2.24	return(0);
109	greg	2.18	}
110	greg	2.5
111	greg	1.1	double
112	greg	2.18	nextssamp( /* compute sample for source, rtn. distance */
113			RAY r, / origin is read, direction is set */
114	greg	2.21	SRCINDEX si / source index (modified to current) */
115	greg	2.18	)
116	greg	1.1	{
117			int cent[3], size[3], parr[2];
118	greg	2.16	SRCREC *srcp;
119	greg	2.19	double vpos[3];
120	greg	1.1	double d;
121	greg	2.18	int i;
122	greg	2.2	nextsample:
123	greg	1.1	while (++si->sp >= si->np) { /* get next sample */
124			if (++si->sn >= nsources)
125			return(0.0); /* no more */
126	greg	2.21	if (srcskip(si->sn, r))
127	greg	1.7	si->np = 0;
128			else if (srcsizerat <= FTINY)
129	greg	1.4	nopart(si, r);
130	greg	1.1	else {
131			for (i = si->sn; source[i].sflags & SVIRTUAL;
132			i = source[i].sa.sv.sn)
133			; /* partition source */
134	greg	1.4	(*sfun[source[i].so->otype].of->partit)(si, r);
135	greg	1.1	}
136			si->sp = -1;
137			}
138			/* get partition */
139			cent[0] = cent[1] = cent[2] = 0;
140			size[0] = size[1] = size[2] = MAXSPART;
141			parr[0] = 0; parr[1] = si->sp;
142			if (!skipparts(cent, size, parr, si->spt))
143			error(CONSISTENCY, "bad source partition in nextssamp");
144			/* compute sample */
145	greg	2.16	srcp = source + si->sn;
146	greg	1.1	if (dstrsrc > FTINY) { /* jitter sample */
147			dimlist[ndims] = si->sn + 8831;
148			dimlist[ndims+1] = si->sp + 3109;
149			d = urand(ilhash(dimlist,ndims+2)+samplendx);
150	greg	2.16	if (srcp->sflags & SFLAT) {
151	greg	1.1	multisamp(vpos, 2, d);
152	greg	2.12	vpos[SW] = 0.5;
153	greg	1.1	} else
154			multisamp(vpos, 3, d);
155			for (i = 0; i < 3; i++)
156			vpos[i] = dstrsrc * (1. - 2.vpos[i])
157	greg	2.17	(double)size[i]*(1.0/MAXSPART);
158	greg	1.1	} else
159			vpos[0] = vpos[1] = vpos[2] = 0.0;
160
161	greg	2.17	VSUM(vpos, vpos, cent, 1.0/MAXSPART);
162	greg	2.12	/* avoid circular aiming failures */
163	greg	2.20	if ((srcp->sflags & SCIR) && (si->np > 1) \| (dstrsrc > 0.7)) {
164	greg	2.12	FVECT trim;
165	greg	2.16	if (srcp->sflags & (SFLAT\|SDISTANT)) {
166	greg	2.12	d = 1.12837917; /* correct setflatss() */
167			trim[SU] = dsqrt(1.0 - 0.5vpos[SV]*vpos[SV]);
168			trim[SV] = dsqrt(1.0 - 0.5vpos[SU]*vpos[SU]);
169			trim[SW] = 0.0;
170			} else {
171			trim[SW] = trim[SU] = vpos[SU]*vpos[SU];
172			d = vpos[SV]*vpos[SV];
173			if (d > trim[SW]) trim[SW] = d;
174			trim[SU] += d;
175			d = vpos[SW]*vpos[SW];
176			if (d > trim[SW]) trim[SW] = d;
177			trim[SU] += d;
178	greg	2.15	if (trim[SU] > FTINY*FTINY) {
179			d = 1.0/0.7236; /* correct sphsetsrc() */
180			trim[SW] = trim[SV] = trim[SU] =
181			d*sqrt(trim[SW]/trim[SU]);
182			} else
183			trim[SW] = trim[SV] = trim[SU] = 0.0;
184	greg	2.12	}
185			for (i = 0; i < 3; i++)
186			vpos[i] *= trim[i];
187			}
188	greg	1.1	/* compute direction */
189			for (i = 0; i < 3; i++)
190	greg	2.16	r->rdir[i] = srcp->sloc[i] +
191			vpos[SU]*srcp->ss[SU][i] +
192			vpos[SV]*srcp->ss[SV][i] +
193			vpos[SW]*srcp->ss[SW][i];
194	greg	1.1
195	greg	2.16	if (!(srcp->sflags & SDISTANT))
196	greg	2.17	VSUB(r->rdir, r->rdir, r->rorg);
197	greg	1.1	/* compute distance */
198	greg	1.4	if ((d = normalize(r->rdir)) == 0.0)
199	greg	2.2	goto nextsample; /* at source! */
200	greg	1.1
201			/* compute sample size */
202	greg	2.16	if (srcp->sflags & SFLAT) {
203	greg	2.6	si->dom = sflatform(si->sn, r->rdir);
204	greg	2.17	si->dom = size[SU]size[SV]*(1.0/MAXSPART/MAXSPART);
205	greg	2.16	} else if (srcp->sflags & SCYL) {
206	greg	2.6	si->dom = scylform(si->sn, r->rdir);
207	greg	2.17	si->dom = size[SU](1.0/MAXSPART);
208	greg	1.1	} else {
209	greg	2.17	si->dom = size[SU]size[SV](double)size[SW] *
210			(1.0/MAXSPART/MAXSPART/MAXSPART) ;
211	greg	1.1	}
212	greg	2.16	if (srcp->sflags & SDISTANT) {
213			si->dom *= srcp->ss2;
214	greg	1.1	return(FHUGE);
215	greg	2.6	}
216	greg	2.3	if (si->dom <= 1e-4)
217	greg	2.2	goto nextsample; /* behind source? */
218	greg	2.16	si->dom = srcp->ss2/(dd);
219	greg	1.1	return(d); /* sample OK, return distance */
220			}
221
222
223	greg	2.7	int
224	greg	2.18	skipparts( /* skip to requested partition */
225			int ct[3],
226			int sz[3], /* center and size of partition (returned) */
227			int pp[2], /* current index, number to skip (modified) */
228			unsigned char pt / partition array */
229			)
230	greg	1.1	{
231	greg	2.18	int p;
232	greg	1.1	/* check this partition */
233			p = spart(pt, pp[0]);
234			pp[0]++;
235	schorsch	2.10	if (p == S0) { /* leaf partition */
236	greg	1.1	if (pp[1]) {
237			pp[1]--;
238			return(0); /* not there yet */
239			} else
240			return(1); /* we've arrived */
241	schorsch	2.10	}
242	greg	1.1	/* else check lower */
243			sz[p] >>= 1;
244			ct[p] -= sz[p];
245			if (skipparts(ct, sz, pp, pt))
246			return(1); /* return hit */
247			/* else check upper */
248			ct[p] += sz[p] << 1;
249			if (skipparts(ct, sz, pp, pt))
250			return(1); /* return hit */
251			/* else return to starting position */
252			ct[p] -= sz[p];
253			sz[p] <<= 1;
254			return(0); /* return miss */
255			}
256
257
258	greg	2.7	void
259	greg	2.18	nopart( /* single source partition */
260			SRCINDEX *si,
261			RAY *r
262			)
263	greg	1.1	{
264			clrpart(si->spt);
265			setpart(si->spt, 0, S0);
266			si->np = 1;
267			}
268
269
270			static int
271	greg	2.18	cyl_partit( /* slice a cylinder */
272			FVECT ro,
273			unsigned char *pt,
274			int *pi,
275			int mp,
276			FVECT cent,
277			FVECT axis,
278			double d2
279			)
280	greg	1.1	{
281			FVECT newct, newax;
282			int npl, npu;
283
284			if (mp < 2 \|\| dist2(ro, cent) >= d2) { /* hit limit? */
285			setpart(pt, *pi, S0);
286			(*pi)++;
287			return(1);
288			}
289			/* subdivide */
290			setpart(pt, *pi, SU);
291			(*pi)++;
292			newax[0] = .5*axis[0];
293			newax[1] = .5*axis[1];
294			newax[2] = .5*axis[2];
295			d2 *= 0.25;
296			/* lower 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	npl = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
301	greg	1.1	/* upper half */
302			newct[0] = cent[0] + newax[0];
303			newct[1] = cent[1] + newax[1];
304			newct[2] = cent[2] + newax[2];
305	greg	1.2	npu = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2);
306	greg	1.1	/* return total */
307			return(npl + npu);
308			}
309
310
311	greg	2.7	void
312	greg	2.18	cylpart( /* partition a cylinder */
313			SRCINDEX *si,
314			RAY *r
315			)
316	greg	1.1	{
317	greg	2.18	double dist2, safedist2, dist2cent, rad2;
318	greg	1.5	FVECT v;
319	greg	2.18	SRCREC *sp;
320	greg	1.1	int pi;
321	greg	2.18	/* first check point location */
322	greg	1.5	clrpart(si->spt);
323	greg	2.18	sp = source + si->sn;
324			rad2 = 1.365 * DOT(sp->ss[SV],sp->ss[SV]);
325			v[0] = r->rorg[0] - sp->sloc[0];
326			v[1] = r->rorg[1] - sp->sloc[1];
327			v[2] = r->rorg[2] - sp->sloc[2];
328			dist2 = DOT(v,sp->ss[SU]);
329			safedist2 = DOT(sp->ss[SU],sp->ss[SU]);
330			dist2 *= dist2 / safedist2;
331			dist2cent = DOT(v,v);
332			dist2 = dist2cent - dist2;
333			if (dist2 <= rad2) { /* point inside extended cylinder */
334	greg	1.5	si->np = 0;
335			return;
336			}
337	greg	2.18	safedist2 = 4.r->rweightr->rweight/(srcsizeratsrcsizerat);
338			if (dist2 <= 4.rad2 \|\| / point too close to subdivide */
339			dist2cent >= safedist2) { /* or too far */
340			setpart(si->spt, 0, S0);
341			si->np = 1;
342			return;
343			}
344	greg	1.1	pi = 0;
345	greg	2.18	si->np = cyl_partit(r->rorg, si->spt, &pi, MAXSPART,
346			sp->sloc, sp->ss[SU], safedist2);
347	greg	1.1	}
348
349
350			static int
351	greg	2.18	flt_partit( /* partition flatty */
352			FVECT ro,
353			unsigned char *pt,
354			int *pi,
355			int mp,
356			FVECT cent,
357			FVECT u,
358			FVECT v,
359			double du2,
360			double dv2
361			)
362	greg	1.1	{
363			double d2;
364			FVECT newct, newax;
365			int npl, npu;
366
367			if (mp < 2 \|\| ((d2 = dist2(ro, cent)) >= du2
368			&& d2 >= dv2)) { /* hit limit? */
369			setpart(pt, *pi, S0);
370			(*pi)++;
371			return(1);
372			}
373			if (du2 > dv2) { /* subdivide in U */
374			setpart(pt, *pi, SU);
375			(*pi)++;
376			newax[0] = .5*u[0];
377			newax[1] = .5*u[1];
378			newax[2] = .5*u[2];
379			u = newax;
380			du2 *= 0.25;
381			} else { /* subdivide in V */
382			setpart(pt, *pi, SV);
383			(*pi)++;
384			newax[0] = .5*v[0];
385			newax[1] = .5*v[1];
386			newax[2] = .5*v[2];
387			v = newax;
388			dv2 *= 0.25;
389			}
390			/* lower half */
391			newct[0] = cent[0] - newax[0];
392			newct[1] = cent[1] - newax[1];
393			newct[2] = cent[2] - newax[2];
394	greg	1.2	npl = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
395	greg	1.1	/* upper half */
396			newct[0] = cent[0] + newax[0];
397			newct[1] = cent[1] + newax[1];
398			newct[2] = cent[2] + newax[2];
399	greg	1.2	npu = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2);
400	greg	1.1	/* return total */
401			return(npl + npu);
402			}
403
404
405	greg	2.18	void
406			flatpart( /* partition a flat source */
407			SRCINDEX *si,
408			RAY *r
409			)
410			{
411			RREAL *vp;
412			FVECT v;
413			double du2, dv2;
414			int pi;
415
416			clrpart(si->spt);
417			vp = source[si->sn].sloc;
418			v[0] = r->rorg[0] - vp[0];
419			v[1] = r->rorg[1] - vp[1];
420			v[2] = r->rorg[2] - vp[2];
421			vp = source[si->sn].snorm;
422			if (DOT(v,vp) <= 0.) { /* behind source */
423			si->np = 0;
424			return;
425			}
426			dv2 = 2.*r->rweight/srcsizerat;
427			dv2 *= dv2;
428			vp = source[si->sn].ss[SU];
429			du2 = dv2 * DOT(vp,vp);
430			vp = source[si->sn].ss[SV];
431			dv2 *= DOT(vp,vp);
432			pi = 0;
433			si->np = flt_partit(r->rorg, si->spt, &pi, MAXSPART,
434			source[si->sn].sloc,
435			source[si->sn].ss[SU], source[si->sn].ss[SV], du2, dv2);
436			}
437
438
439	greg	1.1	double
440	greg	2.18	scylform( /* compute cosine for cylinder's projection */
441			int sn,
442			FVECT dir /* assume normalized */
443			)
444	greg	1.1	{
445	greg	2.18	RREAL *dv;
446	greg	1.1	double d;
447
448			dv = source[sn].ss[SU];
449			d = DOT(dir, dv);
450			d *= d / DOT(dv,dv);
451			return(sqrt(1. - d));
452			}