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greg |
3.1 |
/*
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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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#include <stdio.h>
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#include <stdlib.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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/* 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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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, (1<<nd)*sizeof(st->u.t[0]));
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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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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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/* Free an SD tree */
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static void
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SDfreeTree(void *p)
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{
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SDNode *st = (SDNode *)p;
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int i;
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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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SDfreeTree(st->u.t[i]);
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free((void *)st);
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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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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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/* 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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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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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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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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/* 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 fl)
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{
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return SDEsupport;
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}
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/* Variable resolution BSDF methods */
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const SDFunc SDhandleTre = {
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NULL,
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NULL,
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NULL,
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NULL,
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&SDfreeTree,
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};
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