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#ifndef lint |
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static const char RCSid[] = "$Id: bsdf_t.c,v 3.4 2011/02/19 01:48:59 greg Exp $"; |
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#endif |
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/* |
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* bsdf_t.c |
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* |
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* Definitions for variable-resolution BSDF trees |
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* |
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* Created by Greg Ward on 2/2/11. |
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* |
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*/ |
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|
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#include "rtio.h" |
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#include <stdlib.h> |
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#include <math.h> |
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#include <ctype.h> |
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#include "ezxml.h" |
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#include "bsdf.h" |
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#include "bsdf_t.h" |
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|
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/* Allocate a new scattering distribution node */ |
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static SDNode * |
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SDnewNode(int nd, int lg) |
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{ |
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SDNode *st; |
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|
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if (nd <= 0) { |
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strcpy(SDerrorDetail, "Zero dimension BSDF node request"); |
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return NULL; |
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} |
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if (nd > SD_MAXDIM) { |
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sprintf(SDerrorDetail, "Illegal BSDF dimension (%d > %d)", |
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nd, SD_MAXDIM); |
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return NULL; |
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} |
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if (lg < 0) { |
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st = (SDNode *)malloc(sizeof(SDNode) + |
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((1<<nd) - 1)*sizeof(st->u.t[0])); |
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if (st != NULL) |
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memset(st->u.t, 0, sizeof(st->u.t[0])<<nd); |
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} else |
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st = (SDNode *)malloc(sizeof(SDNode) + |
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((1 << nd*lg) - 1)*sizeof(st->u.v[0])); |
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|
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if (st == NULL) { |
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if (lg < 0) |
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sprintf(SDerrorDetail, |
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"Cannot allocate %d branch BSDF tree", nd); |
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else |
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sprintf(SDerrorDetail, |
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"Cannot allocate %d BSDF leaves", 1 << nd*lg); |
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return NULL; |
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} |
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st->ndim = nd; |
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st->log2GR = lg; |
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return st; |
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} |
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|
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/* Free an SD tree */ |
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static void |
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SDfreeTre(void *p) |
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{ |
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SDNode *st = (SDNode *)p; |
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int i; |
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|
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if (st == NULL) |
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return; |
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for (i = (st->log2GR < 0) << st->ndim; i--; ) |
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SDfreeTre(st->u.t[i]); |
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free((void *)st); |
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} |
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|
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#if 0 /* Unused and untested routines */ |
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|
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/* Add up N-dimensional hypercube array values over the given box */ |
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static double |
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SDiterSum(const float *va, int nd, int siz, const int *imin, const int *imax) |
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{ |
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double sum = .0; |
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unsigned skipsiz = 1; |
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int i; |
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|
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for (i = nd; --i > 0; ) |
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skipsiz *= siz; |
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if (skipsiz == 1) |
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for (i = *imin; i < *imax; i++) |
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sum += va[i]; |
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else |
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for (i = *imin; i < *imax; i++) |
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sum += SDiterSum(va + i*skipsiz, |
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nd-1, siz, imin+1, imax+1); |
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return sum; |
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} |
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|
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/* Average BSDF leaves over an orthotope defined by the unit hypercube */ |
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static double |
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SDavgBox(const SDNode *st, const double *bmin, const double *bmax) |
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{ |
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int imin[SD_MAXDIM], imax[SD_MAXDIM]; |
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unsigned n; |
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int i; |
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|
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if (!st) |
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return .0; |
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/* check box limits */ |
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for (i = st->ndim; i--; ) { |
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if (bmin[i] >= 1.) |
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return .0; |
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if (bmax[i] <= .0) |
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return .0; |
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if (bmin[i] >= bmax[i]) |
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return .0; |
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} |
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if (st->log2GR < 0) { /* iterate on subtree */ |
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double sum = .0, wsum = 1e-20; |
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double sbmin[SD_MAXDIM], sbmax[SD_MAXDIM], w; |
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|
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for (n = 1 << st->ndim; n--; ) { |
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w = 1.; |
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for (i = st->ndim; i--; ) { |
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sbmin[i] = 2.*bmin[i]; |
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sbmax[i] = 2.*bmax[i]; |
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if (n & 1<<i) { |
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sbmin[i] -= 1.; |
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sbmax[i] -= 1.; |
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} |
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if (sbmin[i] < .0) sbmin[i] = .0; |
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if (sbmax[i] > 1.) sbmax[i] = 1.; |
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w *= sbmax[i] - sbmin[i]; |
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} |
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if (w > 1e-10) { |
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sum += w * SDavgBox(st->u.t[n], sbmin, sbmax); |
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wsum += w; |
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} |
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} |
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return sum / wsum; |
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} |
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n = 1; /* iterate over leaves */ |
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for (i = st->ndim; i--; ) { |
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imin[i] = (bmin[i] <= .0) ? 0 |
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: (int)((1 << st->log2GR)*bmin[i]); |
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imax[i] = (bmax[i] >= 1.) ? (1 << st->log2GR) |
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: (int)((1 << st->log2GR)*bmax[i] + .999999); |
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n *= imax[i] - imin[i]; |
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} |
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if (!n) |
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return .0; |
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|
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return SDiterSum(st->u.v, st->ndim, 1 << st->log2GR, imin, imax) / |
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(double)n; |
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} |
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|
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#endif /* 0 */ |
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|
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/* Look up tree value at the given grid position */ |
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static float |
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SDlookupTre(const SDNode *st, const double *pos) |
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{ |
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double spos[SD_MAXDIM]; |
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int i, n, t; |
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/* climb the tree */ |
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while (st->log2GR < 0) { |
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n = 0; /* move to appropriate branch */ |
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for (i = st->ndim; i--; ) { |
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spos[i] = 2.*pos[i]; |
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t = (spos[i] >= 1.); |
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n |= t<<i; |
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spos[i] -= (double)t; |
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} |
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st = st->u.t[n]; /* avoids tail recursion */ |
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pos = spos; |
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} |
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n = t = 0; /* find grid array index */ |
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for (i = st->ndim; i--; ) { |
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n += (int)((1<<st->log2GR)*pos[i]) << t; |
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t += st->log2GR; |
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} |
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return st->u.v[n]; /* XXX no interpolation */ |
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} |
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|
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/* Compute non-diffuse component for variable-resolution BSDF */ |
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static int |
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SDgetTreBSDF(float coef[SDmaxCh], const FVECT outVec, |
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const FVECT inVec, const void *dist) |
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{ |
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const SDNode *st = (const SDNode *)dist; |
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double gridPos[4]; |
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/* convert vector coordinates */ |
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if (st->ndim == 3) { /* reduce for isotropic BSDF? */ |
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static const FVECT zvec = {.0, .0, 1.}; |
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FVECT rOutVec; |
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spinvector(rOutVec, outVec, zvec, -atan2(inVec[1],inVec[0])); |
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SDdisk2square(gridPos, rOutVec[0], rOutVec[1]); |
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gridPos[2] = .5 - .5*sqrt(inVec[0]*inVec[0] + inVec[1]*inVec[1]); |
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} else if (st->ndim == 4) { /* XXX no component identity checks */ |
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SDdisk2square(gridPos, outVec[0], outVec[1]); |
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SDdisk2square(gridPos+2, -inVec[0], -inVec[1]); |
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} else |
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return 0; /* should be internal error */ |
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/* get nearest BSDF value */ |
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coef[0] = SDlookupTre(st, gridPos); |
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return 1; /* monochromatic for now */ |
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} |
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|
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/* Load a variable-resolution BSDF tree from an open XML file */ |
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SDError |
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SDloadTre(SDData *sd, ezxml_t wtl) |
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{ |
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return SDEsupport; |
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} |
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|
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/* Variable resolution BSDF methods */ |
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SDFunc SDhandleTre = { |
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&SDgetTreBSDF, |
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NULL, |
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NULL, |
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NULL, |
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&SDfreeTre, |
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}; |
