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/* Copyright (c) 1991 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* Source sampling routines |
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* |
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* External symbols declared in source.h |
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*/ |
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#include "copyright.h" |
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#include "ray.h" |
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#include "source.h" |
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#include "random.h" |
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static int cyl_partit(), flt_partit(); |
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|
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double |
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nextssamp(r, si) /* compute sample for source, rtn. distance */ |
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register RAY *r; /* origin is read, direction is set */ |
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register SRCINDEX *si; /* source index (modified to current) */ |
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{ |
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int cent[3], size[3], parr[2]; |
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SRCREC *srcp; |
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FVECT vpos; |
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double d; |
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register int i; |
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nextsample: |
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while (++si->sp >= si->np) { /* get next sample */ |
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if (++si->sn >= nsources) |
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return(0.0); /* no more */ |
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if (!skipparts(cent, size, parr, si->spt)) |
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error(CONSISTENCY, "bad source partition in nextssamp"); |
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/* compute sample */ |
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srcp = source + si->sn; |
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if (dstrsrc > FTINY) { /* jitter sample */ |
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dimlist[ndims] = si->sn + 8831; |
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dimlist[ndims+1] = si->sp + 3109; |
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d = urand(ilhash(dimlist,ndims+2)+samplendx); |
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if (source[si->sn].sflags & SFLAT) { |
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if (srcp->sflags & SFLAT) { |
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multisamp(vpos, 2, d); |
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vpos[2] = 0.5; |
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vpos[SW] = 0.5; |
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} else |
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multisamp(vpos, 3, d); |
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for (i = 0; i < 3; i++) |
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for (i = 0; i < 3; i++) |
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vpos[i] += (double)cent[i]/MAXSPART; |
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/* avoid circular aiming failures */ |
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if ((srcp->sflags & SCIR) && (si->np > 1 || dstrsrc > 0.7)) { |
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FVECT trim; |
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if (srcp->sflags & (SFLAT|SDISTANT)) { |
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d = 1.12837917; /* correct setflatss() */ |
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trim[SU] = d*sqrt(1.0 - 0.5*vpos[SV]*vpos[SV]); |
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trim[SV] = d*sqrt(1.0 - 0.5*vpos[SU]*vpos[SU]); |
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trim[SW] = 0.0; |
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} else { |
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trim[SW] = trim[SU] = vpos[SU]*vpos[SU]; |
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d = vpos[SV]*vpos[SV]; |
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if (d > trim[SW]) trim[SW] = d; |
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trim[SU] += d; |
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d = vpos[SW]*vpos[SW]; |
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if (d > trim[SW]) trim[SW] = d; |
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trim[SU] += d; |
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if (trim[SU] > FTINY*FTINY) { |
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d = 1.0/0.7236; /* correct sphsetsrc() */ |
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trim[SW] = trim[SV] = trim[SU] = |
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d*sqrt(trim[SW]/trim[SU]); |
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} else |
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trim[SW] = trim[SV] = trim[SU] = 0.0; |
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} |
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for (i = 0; i < 3; i++) |
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vpos[i] *= trim[i]; |
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} |
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/* compute direction */ |
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for (i = 0; i < 3; i++) |
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r->rdir[i] = source[si->sn].sloc[i] + |
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vpos[SU]*source[si->sn].ss[SU][i] + |
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vpos[SV]*source[si->sn].ss[SV][i] + |
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vpos[SW]*source[si->sn].ss[SW][i]; |
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r->rdir[i] = srcp->sloc[i] + |
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vpos[SU]*srcp->ss[SU][i] + |
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vpos[SV]*srcp->ss[SV][i] + |
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vpos[SW]*srcp->ss[SW][i]; |
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if (!(source[si->sn].sflags & SDISTANT)) |
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if (!(srcp->sflags & SDISTANT)) |
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for (i = 0; i < 3; i++) |
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r->rdir[i] -= r->rorg[i]; |
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/* compute distance */ |
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if ((d = normalize(r->rdir)) == 0.0) |
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return(nextssamp(r, si)); /* at source! */ |
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goto nextsample; /* at source! */ |
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/* compute sample size */ |
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si->dom = source[si->sn].ss2; |
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if (source[si->sn].sflags & SFLAT) { |
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si->dom *= sflatform(si->sn, r->rdir); |
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si->dom *= (double)(size[SU]*size[SV])/(MAXSPART*MAXSPART); |
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} else if (source[si->sn].sflags & SCYL) { |
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si->dom *= scylform(si->sn, r->rdir); |
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si->dom *= (double)size[SU]/MAXSPART; |
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if (srcp->sflags & SFLAT) { |
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si->dom = sflatform(si->sn, r->rdir); |
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si->dom *= size[SU]*size[SV]/(MAXSPART*(double)MAXSPART); |
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} else if (srcp->sflags & SCYL) { |
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si->dom = scylform(si->sn, r->rdir); |
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si->dom *= size[SU]/(double)MAXSPART; |
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} else { |
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si->dom *= (double)(size[SU]*size[SV]*size[SW]) / |
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(MAXSPART*MAXSPART*MAXSPART) ; |
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si->dom = size[SU]*size[SV]*(double)size[SW] / |
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(MAXSPART*MAXSPART*(double)MAXSPART) ; |
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} |
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if (source[si->sn].sflags & SDISTANT) |
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if (srcp->sflags & SDISTANT) { |
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si->dom *= srcp->ss2; |
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return(FHUGE); |
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si->dom /= d*d; |
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} |
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if (si->dom <= 1e-4) |
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goto nextsample; /* behind source? */ |
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si->dom *= srcp->ss2/(d*d); |
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return(d); /* sample OK, return distance */ |
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} |
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int |
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skipparts(ct, sz, pp, pt) /* skip to requested partition */ |
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int ct[3], sz[3]; /* center and size of partition (returned) */ |
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register int pp[2]; /* current index, number to skip (modified) */ |
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/* check this partition */ |
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p = spart(pt, pp[0]); |
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pp[0]++; |
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if (p == S0) /* leaf partition */ |
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if (p == S0) { /* leaf partition */ |
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if (pp[1]) { |
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pp[1]--; |
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return(0); /* not there yet */ |
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} else |
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return(1); /* we've arrived */ |
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} |
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/* else check lower */ |
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sz[p] >>= 1; |
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ct[p] -= sz[p]; |
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} |
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void |
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nopart(si, r) /* single source partition */ |
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register SRCINDEX *si; |
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RAY *r; |
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} |
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void |
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cylpart(si, r) /* partition a cylinder */ |
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SRCINDEX *si; |
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register RAY *r; |
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} |
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void |
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flatpart(si, r) /* partition a flat source */ |
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register SRCINDEX *si; |
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register RAY *r; |
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{ |
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register FLOAT *vp; |
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register RREAL *vp; |
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FVECT v; |
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double du2, dv2; |
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int pi; |
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v[1] = r->rorg[1] - vp[1]; |
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v[2] = r->rorg[2] - vp[2]; |
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vp = source[si->sn].snorm; |
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if (DOT(v,vp) <= FTINY) { /* behind source */ |
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if (DOT(v,vp) <= 0.) { /* behind source */ |
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si->np = 0; |
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return; |
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} |
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int sn; |
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register FVECT dir; /* assume normalized */ |
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{ |
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register FLOAT *dv; |
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register RREAL *dv; |
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double d; |
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dv = source[sn].ss[SU]; |