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#ifndef lint |
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static const char RCSid[] = "$Id: ambcomp.c,v 2.18 2005/06/06 19:14:28 greg Exp $"; |
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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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|
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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 "ambient.h" |
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|
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#include "random.h" |
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|
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|
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void |
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inithemi( /* initialize sampling hemisphere */ |
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register AMBHEMI *hp, |
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COLOR ac, |
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RAY *r, |
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double wt |
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) |
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{ |
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double d; |
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register int i; |
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/* set number of divisions */ |
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if (ambacc <= FTINY && |
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wt > (d = 0.8*bright(ac)*r->rweight/(ambdiv*minweight))) |
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wt = d; /* avoid ray termination */ |
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hp->nt = sqrt(ambdiv * wt / PI) + 0.5; |
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i = ambacc > FTINY ? 3 : 1; /* minimum number of samples */ |
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if (hp->nt < i) |
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hp->nt = i; |
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hp->np = PI * hp->nt + 0.5; |
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/* set number of super-samples */ |
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hp->ns = ambssamp * wt + 0.5; |
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/* assign coefficient */ |
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copycolor(hp->acoef, ac); |
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d = 1.0/(hp->nt*hp->np); |
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scalecolor(hp->acoef, d); |
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/* make axes */ |
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VCOPY(hp->uz, r->ron); |
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hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0; |
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for (i = 0; i < 3; i++) |
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if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6) |
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break; |
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if (i >= 3) |
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error(CONSISTENCY, "bad ray direction in inithemi"); |
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hp->uy[i] = 1.0; |
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fcross(hp->ux, hp->uy, hp->uz); |
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normalize(hp->ux); |
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fcross(hp->uy, hp->uz, hp->ux); |
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} |
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|
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|
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int |
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divsample( /* sample a division */ |
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register AMBSAMP *dp, |
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AMBHEMI *h, |
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RAY *r |
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) |
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{ |
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RAY ar; |
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int hlist[3]; |
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double spt[2]; |
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double xd, yd, zd; |
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double b2; |
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double phi; |
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register int i; |
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/* ambient coefficient for weight */ |
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if (ambacc > FTINY) |
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setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL); |
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else |
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copycolor(ar.rcoef, h->acoef); |
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if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0) |
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return(-1); |
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if (ambacc > FTINY) { |
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multcolor(ar.rcoef, h->acoef); |
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scalecolor(ar.rcoef, 1./AVGREFL); |
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} |
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hlist[0] = r->rno; |
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hlist[1] = dp->t; |
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hlist[2] = dp->p; |
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multisamp(spt, 2, urand(ilhash(hlist,3)+dp->n)); |
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zd = sqrt((dp->t + spt[0])/h->nt); |
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phi = 2.0*PI * (dp->p + spt[1])/h->np; |
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xd = tcos(phi) * zd; |
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yd = tsin(phi) * zd; |
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zd = sqrt(1.0 - zd*zd); |
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for (i = 0; i < 3; i++) |
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ar.rdir[i] = xd*h->ux[i] + |
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yd*h->uy[i] + |
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zd*h->uz[i]; |
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dimlist[ndims++] = dp->t*h->np + dp->p + 90171; |
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rayvalue(&ar); |
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ndims--; |
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multcolor(ar.rcol, ar.rcoef); /* apply coefficient */ |
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addcolor(dp->v, ar.rcol); |
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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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b2 = b2*b2 + dp->k*((dp->n-1)*(dp->n-1)); |
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dp->k = b2/(dp->n*dp->n); |
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} else |
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dp->k = 0.0; |
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return(0); |
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} |
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|
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|
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static int |
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ambcmp( /* decreasing order */ |
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const void *p1, |
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const void *p2 |
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) |
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{ |
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const AMBSAMP *d1 = (const AMBSAMP *)p1; |
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const AMBSAMP *d2 = (const AMBSAMP *)p2; |
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|
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if (d1->k < d2->k) |
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return(1); |
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if (d1->k > d2->k) |
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return(-1); |
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return(0); |
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} |
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|
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|
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static int |
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ambnorm( /* standard order */ |
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const void *p1, |
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const void *p2 |
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) |
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{ |
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const AMBSAMP *d1 = (const AMBSAMP *)p1; |
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const AMBSAMP *d2 = (const AMBSAMP *)p2; |
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register int c; |
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|
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if ( (c = d1->t - d2->t) ) |
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return(c); |
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return(d1->p - d2->p); |
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} |
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|
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|
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double |
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doambient( /* compute ambient component */ |
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COLOR acol, |
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RAY *r, |
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double wt, |
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FVECT pg, |
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FVECT dg |
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) |
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{ |
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double b, d; |
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AMBHEMI hemi; |
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AMBSAMP *div; |
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AMBSAMP dnew; |
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register AMBSAMP *dp; |
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double arad; |
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int divcnt; |
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register int i, j; |
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/* initialize hemisphere */ |
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inithemi(&hemi, acol, r, wt); |
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divcnt = hemi.nt * hemi.np; |
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/* initialize */ |
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if (pg != NULL) |
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pg[0] = pg[1] = pg[2] = 0.0; |
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if (dg != NULL) |
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dg[0] = dg[1] = dg[2] = 0.0; |
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setcolor(acol, 0.0, 0.0, 0.0); |
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if (divcnt == 0) |
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return(0.0); |
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/* allocate super-samples */ |
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if (hemi.ns > 0 || pg != NULL || dg != NULL) { |
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div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP)); |
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if (div == NULL) |
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error(SYSTEM, "out of memory in doambient"); |
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} else |
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div = NULL; |
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/* sample the divisions */ |
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arad = 0.0; |
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if ((dp = div) == NULL) |
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dp = &dnew; |
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divcnt = 0; |
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for (i = 0; i < hemi.nt; i++) |
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for (j = 0; j < hemi.np; j++) { |
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dp->t = i; dp->p = j; |
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setcolor(dp->v, 0.0, 0.0, 0.0); |
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dp->r = 0.0; |
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dp->n = 0; |
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if (divsample(dp, &hemi, r) < 0) { |
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if (div != NULL) |
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dp++; |
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continue; |
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} |
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arad += dp->r; |
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divcnt++; |
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if (div != NULL) |
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dp++; |
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else |
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addcolor(acol, dp->v); |
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} |
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if (!divcnt) |
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return(0.0); /* no samples taken */ |
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if (divcnt < hemi.nt*hemi.np) { |
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pg = dg = NULL; /* incomplete sampling */ |
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hemi.ns = 0; |
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} else if (arad > FTINY && divcnt/arad < minarad) { |
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hemi.ns = 0; /* close enough */ |
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} else if (hemi.ns > 0) { /* else perform super-sampling? */ |
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comperrs(div, &hemi); /* compute errors */ |
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qsort(div, divcnt, sizeof(AMBSAMP), ambcmp); /* sort divs */ |
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/* super-sample */ |
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for (i = hemi.ns; i > 0; i--) { |
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dnew = *div; |
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if (divsample(&dnew, &hemi, r) < 0) { |
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dp++; |
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continue; |
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} |
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dp = div; /* reinsert */ |
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j = divcnt < i ? divcnt : i; |
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while (--j > 0 && dnew.k < dp[1].k) { |
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*dp = *(dp+1); |
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dp++; |
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} |
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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, divcnt, sizeof(AMBSAMP), ambnorm); |
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} |
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/* compute returned values */ |
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if (div != NULL) { |
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arad = 0.0; /* note: divcnt may be < nt*np */ |
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for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) { |
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arad += dp->r; |
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if (dp->n > 1) { |
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b = 1.0/dp->n; |
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scalecolor(dp->v, b); |
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dp->r *= b; |
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dp->n = 1; |
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} |
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addcolor(acol, dp->v); |
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} |
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b = bright(acol); |
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if (b > FTINY) { |
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b = 1.0/b; /* compute & normalize gradient(s) */ |
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if (pg != NULL) { |
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posgradient(pg, div, &hemi); |
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for (i = 0; i < 3; i++) |
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pg[i] *= b; |
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} |
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if (dg != NULL) { |
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dirgradient(dg, div, &hemi); |
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for (i = 0; i < 3; i++) |
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dg[i] *= b; |
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} |
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} |
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free((void *)div); |
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} |
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if (arad <= FTINY) |
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arad = maxarad; |
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else |
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arad = (divcnt+hemi.ns)/arad; |
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if (pg != NULL) { /* reduce radius if gradient large */ |
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d = DOT(pg,pg); |
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if (d*arad*arad > 1.0) |
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arad = 1.0/sqrt(d); |
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} |
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if (arad < minarad) { |
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arad = minarad; |
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if (pg != NULL && d*arad*arad > 1.0) { /* cap gradient */ |
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d = 1.0/arad/sqrt(d); |
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for (i = 0; i < 3; i++) |
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pg[i] *= d; |
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} |
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} |
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if ((arad /= sqrt(wt)) > maxarad) |
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arad = maxarad; |
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return(arad); |
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} |
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|
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|
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void |
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comperrs( /* 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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{ |
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double b, b2; |
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int i, j; |
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register AMBSAMP *dp; |
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/* sum differences from neighbors */ |
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dp = da; |
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for (i = 0; i < hp->nt; i++) |
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for (j = 0; j < hp->np; j++) { |
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#ifdef DEBUG |
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if (dp->t != i || dp->p != j) |
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error(CONSISTENCY, |
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"division order in comperrs"); |
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#endif |
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b = bright(dp[0].v); |
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if (i > 0) { /* from above */ |
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b2 = bright(dp[-hp->np].v) - b; |
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b2 *= b2 * 0.25; |
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dp[0].k += b2; |
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dp[-hp->np].k += b2; |
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} |
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if (j > 0) { /* from behind */ |
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b2 = bright(dp[-1].v) - b; |
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b2 *= b2 * 0.25; |
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dp[0].k += b2; |
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dp[-1].k += b2; |
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} else { /* around */ |
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b2 = bright(dp[hp->np-1].v) - b; |
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b2 *= b2 * 0.25; |
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dp[0].k += b2; |
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dp[hp->np-1].k += b2; |
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} |
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dp++; |
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} |
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/* divide by number of neighbors */ |
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dp = da; |
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for (j = 0; j < hp->np; j++) /* top row */ |
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(dp++)->k *= 1.0/3.0; |
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if (hp->nt < 2) |
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return; |
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for (i = 1; i < hp->nt-1; i++) /* central region */ |
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for (j = 0; j < hp->np; j++) |
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(dp++)->k *= 0.25; |
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for (j = 0; j < hp->np; j++) /* bottom row */ |
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(dp++)->k *= 1.0/3.0; |
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} |
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|
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|
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void |
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posgradient( /* compute position gradient */ |
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FVECT gv, |
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AMBSAMP *da, /* assumes standard ordering */ |
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register AMBHEMI *hp |
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) |
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{ |
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register int i, j; |
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double nextsine, lastsine, b, d; |
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double mag0, mag1; |
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double phi, cosp, sinp, xd, yd; |
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register AMBSAMP *dp; |
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|
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xd = yd = 0.0; |
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for (j = 0; j < hp->np; j++) { |
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dp = da + j; |
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mag0 = mag1 = 0.0; |
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lastsine = 0.0; |
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for (i = 0; i < hp->nt; i++) { |
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#ifdef DEBUG |
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if (dp->t != i || dp->p != j) |
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error(CONSISTENCY, |
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"division order in posgradient"); |
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#endif |
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b = bright(dp->v); |
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if (i > 0) { |
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d = dp[-hp->np].r; |
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if (dp[0].r > d) d = dp[0].r; |
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/* sin(t)*cos(t)^2 */ |
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d *= lastsine * (1.0 - (double)i/hp->nt); |
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mag0 += d*(b - bright(dp[-hp->np].v)); |
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} |
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nextsine = sqrt((double)(i+1)/hp->nt); |
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if (j > 0) { |
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d = dp[-1].r; |
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if (dp[0].r > d) d = dp[0].r; |
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mag1 += d * (nextsine - lastsine) * |
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(b - bright(dp[-1].v)); |
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} else { |
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d = dp[hp->np-1].r; |
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if (dp[0].r > d) d = dp[0].r; |
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mag1 += d * (nextsine - lastsine) * |
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(b - bright(dp[hp->np-1].v)); |
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} |
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dp += hp->np; |
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lastsine = nextsine; |
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} |
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mag0 *= 2.0*PI / hp->np; |
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phi = 2.0*PI * (double)j/hp->np; |
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cosp = tcos(phi); sinp = tsin(phi); |
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xd += mag0*cosp - mag1*sinp; |
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yd += mag0*sinp + mag1*cosp; |
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} |
| 392 |
for (i = 0; i < 3; i++) |
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gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI; |
| 394 |
} |
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|
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|
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void |
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dirgradient( /* compute direction gradient */ |
| 399 |
FVECT gv, |
| 400 |
AMBSAMP *da, /* assumes standard ordering */ |
| 401 |
register AMBHEMI *hp |
| 402 |
) |
| 403 |
{ |
| 404 |
register int i, j; |
| 405 |
double mag; |
| 406 |
double phi, xd, yd; |
| 407 |
register AMBSAMP *dp; |
| 408 |
|
| 409 |
xd = yd = 0.0; |
| 410 |
for (j = 0; j < hp->np; j++) { |
| 411 |
dp = da + j; |
| 412 |
mag = 0.0; |
| 413 |
for (i = 0; i < hp->nt; i++) { |
| 414 |
#ifdef DEBUG |
| 415 |
if (dp->t != i || dp->p != j) |
| 416 |
error(CONSISTENCY, |
| 417 |
"division order in dirgradient"); |
| 418 |
#endif |
| 419 |
/* tan(t) */ |
| 420 |
mag += bright(dp->v)/sqrt(hp->nt/(i+.5) - 1.0); |
| 421 |
dp += hp->np; |
| 422 |
} |
| 423 |
phi = 2.0*PI * (j+.5)/hp->np + PI/2.0; |
| 424 |
xd += mag * tcos(phi); |
| 425 |
yd += mag * tsin(phi); |
| 426 |
} |
| 427 |
for (i = 0; i < 3; i++) |
| 428 |
gv[i] = xd*hp->ux[i] + yd*hp->uy[i]; |
| 429 |
} |
