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/* Copyright (c) 1998 Silicon Graphics, Inc. */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ SGI"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* Routines to compute "ambient" values using Monte Carlo |
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* |
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* Declarations of external symbols in ambient.h |
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*/ |
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#include "copyright.h" |
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#include "ray.h" |
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#include "ambient.h" |
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#include "random.h" |
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typedef struct { |
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short t, p; /* theta, phi indices */ |
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COLOR v; /* value sum */ |
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float r; /* 1/distance sum */ |
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float k; /* variance for this division */ |
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int n; /* number of subsamples */ |
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} AMBSAMP; /* ambient sample division */ |
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typedef struct { |
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FVECT ux, uy, uz; /* x, y and z axis directions */ |
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short nt, np; /* number of theta and phi directions */ |
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} AMBHEMI; /* ambient sample hemisphere */ |
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static int |
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ambcmp(d1, d2) /* decreasing order */ |
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AMBSAMP *d1, *d2; |
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} |
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int |
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divsample(dp, h, r) /* sample a division */ |
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register AMBSAMP *dp; |
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AMBHEMI *h; |
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rayvalue(&ar); |
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ndims--; |
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addcolor(dp->v, ar.rcol); |
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/* be conservative and use rot */ |
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if (ar.rot > FTINY && ar.rot < FHUGE) |
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dp->r += 1.0/ar.rot; |
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/* use rt to improve gradient calc */ |
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if (ar.rt > FTINY && ar.rt < FHUGE) |
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dp->r += 1.0/ar.rt; |
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/* (re)initialize error */ |
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if (dp->n++) { |
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b2 = bright(dp->v)/dp->n - bright(ar.rcol); |
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qsort(div, ndivs, sizeof(AMBSAMP), ambcmp); /* sort divs */ |
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/* super-sample */ |
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for (i = ns; i > 0; i--) { |
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copystruct(&dnew, div); |
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dnew = *div; |
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if (divsample(&dnew, &hemi, r) < 0) |
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goto oopsy; |
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/* reinsert */ |
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dp = div; |
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j = ndivs < i ? ndivs : i; |
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while (--j > 0 && dnew.k < dp[1].k) { |
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copystruct(dp, dp+1); |
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*dp = *(dp+1); |
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dp++; |
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} |
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copystruct(dp, &dnew); |
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*dp = dnew; |
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} |
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if (pg != NULL || dg != NULL) /* restore order */ |
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qsort(div, ndivs, sizeof(AMBSAMP), ambnorm); |
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for (i = 0; i < 3; i++) |
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dg[i] = 0.0; |
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} |
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free((char *)div); |
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free((void *)div); |
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} |
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b = 1.0/ndivs; |
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scalecolor(acol, b); |
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return(arad); |
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oopsy: |
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if (div != NULL) |
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free((char *)div); |
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free((void *)div); |
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return(0.0); |
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} |
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void |
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inithemi(hp, r, wt) /* initialize sampling hemisphere */ |
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register AMBHEMI *hp; |
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RAY *r; |
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} |
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void |
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comperrs(da, hp) /* compute initial error estimates */ |
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AMBSAMP *da; /* assumes standard ordering */ |
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register AMBHEMI *hp; |
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} |
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void |
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posgradient(gv, da, hp) /* compute position gradient */ |
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FVECT gv; |
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AMBSAMP *da; /* assumes standard ordering */ |
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} |
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void |
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dirgradient(gv, da, hp) /* compute direction gradient */ |
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FVECT gv; |
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AMBSAMP *da; /* assumes standard ordering */ |
