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#ifndef lint |
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static const char RCSid[] = "$Id: srcsamp.c,v 2.24 2024/12/25 17:40:27 greg Exp $"; |
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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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|
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#include "copyright.h" |
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|
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#include "ray.h" |
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|
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#include "source.h" |
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|
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#include "random.h" |
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|
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|
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int |
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srcskip( /* pre-emptive test for source to skip */ |
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int sn, |
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RAY *r |
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) |
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{ |
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SRCREC *sp = source + sn; |
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|
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if (sp->sflags & SSKIP) |
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return(1); |
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if ((sp->sflags & (SPROX|SDISTANT)) == SPROX) |
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return(dist2(r->rorg, sp->sloc) > |
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(sp->sl.prox + sp->srad)*(sp->sl.prox + sp->srad)); |
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return(0); |
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} |
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|
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double |
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nextssamp( /* compute sample for source, rtn. distance */ |
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RAY *r, /* origin is read, direction is set */ |
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SRCINDEX *si /* source index (modified to current) */ |
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) |
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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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double vpos[3]; |
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double d; |
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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 (srcskip(si->sn, r)) |
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si->np = 0; |
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else if (srcsizerat <= FTINY) |
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nopart(si, r); |
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else { |
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for (i = si->sn; source[i].sflags & SVIRTUAL; |
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i = source[i].sa.sv.sn) |
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; /* partition source */ |
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(*sfun[source[i].so->otype].of->partit)(si, r); |
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} |
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si->sp = -1; |
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} |
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/* get partition */ |
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cent[0] = cent[1] = cent[2] = 0; |
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size[0] = size[1] = size[2] = MAXSPART; |
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parr[0] = 0; parr[1] = si->sp; |
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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 (srcp->sflags & SFLAT) { |
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multisamp(vpos, 2, d); |
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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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vpos[i] = dstrsrc * (1. - 2.*vpos[i]) * |
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(double)size[i]*(1.0/MAXSPART); |
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} else |
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vpos[0] = vpos[1] = vpos[2] = 0.0; |
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|
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VSUM(vpos, vpos, cent, 1.0/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] = 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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|
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if (!(srcp->sflags & SDISTANT)) |
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VSUB(r->rdir, r->rdir, r->rorg); |
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/* compute distance */ |
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if ((d = normalize(r->rdir)) == 0.0) |
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goto nextsample; /* at source! */ |
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|
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/* compute sample size */ |
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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]*(1.0/MAXSPART/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]*(1.0/MAXSPART); |
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} else { |
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si->dom = size[SU]*size[SV]*(double)size[SW] * |
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(1.0/MAXSPART/MAXSPART/MAXSPART) ; |
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} |
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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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} |
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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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|
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|
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int |
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skipparts( /* skip to requested partition */ |
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int ct[3], |
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int sz[3], /* center and size of partition (returned) */ |
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int pp[2], /* current index, number to skip (modified) */ |
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unsigned char *pt /* partition array */ |
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) |
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{ |
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int p; |
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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 (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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if (skipparts(ct, sz, pp, pt)) |
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return(1); /* return hit */ |
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/* else check upper */ |
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ct[p] += sz[p] << 1; |
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if (skipparts(ct, sz, pp, pt)) |
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return(1); /* return hit */ |
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/* else return to starting position */ |
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ct[p] -= sz[p]; |
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sz[p] <<= 1; |
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return(0); /* return miss */ |
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} |
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|
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|
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void |
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nopart( /* single source partition */ |
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SRCINDEX *si, |
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RAY *r |
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) |
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{ |
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clrpart(si->spt); |
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setpart(si->spt, 0, S0); |
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si->np = 1; |
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} |
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|
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|
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static int |
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cyl_partit( /* slice a cylinder */ |
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FVECT ro, |
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unsigned char *pt, |
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int *pi, |
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int mp, |
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FVECT cent, |
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FVECT axis, |
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double d2 |
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) |
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{ |
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FVECT newct, newax; |
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int npl, npu; |
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|
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if (mp < 2 || dist2(ro, cent) >= d2) { /* hit limit? */ |
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setpart(pt, *pi, S0); |
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(*pi)++; |
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return(1); |
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} |
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/* subdivide */ |
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setpart(pt, *pi, SU); |
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(*pi)++; |
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newax[0] = .5*axis[0]; |
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newax[1] = .5*axis[1]; |
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newax[2] = .5*axis[2]; |
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d2 *= 0.25; |
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/* lower half */ |
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newct[0] = cent[0] - newax[0]; |
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newct[1] = cent[1] - newax[1]; |
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newct[2] = cent[2] - newax[2]; |
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npl = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2); |
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/* upper half */ |
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newct[0] = cent[0] + newax[0]; |
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newct[1] = cent[1] + newax[1]; |
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newct[2] = cent[2] + newax[2]; |
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npu = cyl_partit(ro, pt, pi, mp/2, newct, newax, d2); |
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/* return total */ |
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return(npl + npu); |
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} |
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|
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|
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void |
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cylpart( /* partition a cylinder */ |
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SRCINDEX *si, |
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RAY *r |
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) |
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{ |
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double dist2, safedist2, dist2cent, rad2; |
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FVECT v; |
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SRCREC *sp; |
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int pi; |
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/* first check point location */ |
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clrpart(si->spt); |
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sp = source + si->sn; |
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rad2 = 1.365 * DOT(sp->ss[SV],sp->ss[SV]); |
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v[0] = r->rorg[0] - sp->sloc[0]; |
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v[1] = r->rorg[1] - sp->sloc[1]; |
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v[2] = r->rorg[2] - sp->sloc[2]; |
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dist2 = DOT(v,sp->ss[SU]); |
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safedist2 = DOT(sp->ss[SU],sp->ss[SU]); |
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dist2 *= dist2 / safedist2; |
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dist2cent = DOT(v,v); |
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dist2 = dist2cent - dist2; |
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if (dist2 <= rad2) { /* point inside extended cylinder */ |
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si->np = 0; |
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return; |
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} |
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safedist2 *= 4.*r->rweight*r->rweight/(srcsizerat*srcsizerat); |
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if (dist2 <= 4.*rad2 || /* point too close to subdivide */ |
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dist2cent >= safedist2) { /* or too far */ |
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setpart(si->spt, 0, S0); |
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si->np = 1; |
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return; |
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} |
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pi = 0; |
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si->np = cyl_partit(r->rorg, si->spt, &pi, MAXSPART, |
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sp->sloc, sp->ss[SU], safedist2); |
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} |
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|
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|
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static int |
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flt_partit( /* partition flatty */ |
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FVECT ro, |
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unsigned char *pt, |
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int *pi, |
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int mp, |
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FVECT cent, |
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FVECT u, |
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FVECT v, |
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double du2, |
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double dv2 |
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) |
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{ |
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double d2; |
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FVECT newct, newax; |
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int npl, npu; |
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|
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if (mp < 2 || ((d2 = dist2(ro, cent)) >= du2 |
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&& d2 >= dv2)) { /* hit limit? */ |
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setpart(pt, *pi, S0); |
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(*pi)++; |
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return(1); |
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} |
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if (du2 > dv2) { /* subdivide in U */ |
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setpart(pt, *pi, SU); |
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(*pi)++; |
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newax[0] = .5*u[0]; |
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newax[1] = .5*u[1]; |
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newax[2] = .5*u[2]; |
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u = newax; |
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du2 *= 0.25; |
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} else { /* subdivide in V */ |
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setpart(pt, *pi, SV); |
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(*pi)++; |
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newax[0] = .5*v[0]; |
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newax[1] = .5*v[1]; |
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newax[2] = .5*v[2]; |
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v = newax; |
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dv2 *= 0.25; |
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} |
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/* lower half */ |
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newct[0] = cent[0] - newax[0]; |
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newct[1] = cent[1] - newax[1]; |
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newct[2] = cent[2] - newax[2]; |
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npl = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2); |
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/* upper half */ |
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newct[0] = cent[0] + newax[0]; |
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newct[1] = cent[1] + newax[1]; |
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newct[2] = cent[2] + newax[2]; |
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npu = flt_partit(ro, pt, pi, mp/2, newct, u, v, du2, dv2); |
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/* return total */ |
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return(npl + npu); |
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} |
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|
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|
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void |
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flatpart( /* partition a flat source */ |
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SRCINDEX *si, |
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RAY *r |
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) |
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{ |
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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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|
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clrpart(si->spt); |
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vp = source[si->sn].sloc; |
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v[0] = r->rorg[0] - vp[0]; |
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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) <= 0.) { /* behind source */ |
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si->np = 0; |
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return; |
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} |
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dv2 = 2.*r->rweight/srcsizerat; |
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dv2 *= dv2; |
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vp = source[si->sn].ss[SU]; |
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du2 = dv2 * DOT(vp,vp); |
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vp = source[si->sn].ss[SV]; |
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dv2 *= DOT(vp,vp); |
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pi = 0; |
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si->np = flt_partit(r->rorg, si->spt, &pi, MAXSPART, |
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source[si->sn].sloc, |
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source[si->sn].ss[SU], source[si->sn].ss[SV], du2, dv2); |
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} |
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|
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|
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double |
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scylform( /* compute cosine for cylinder's projection */ |
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int sn, |
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FVECT dir /* assume normalized */ |
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) |
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{ |
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RREAL *dv; |
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double d; |
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|
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dv = source[sn].ss[SU]; |
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d = DOT(dir, dv); |
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d *= d / DOT(dv,dv); |
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return(sqrt(1. - d)); |
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} |
