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#ifndef lint
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static const char RCSid[] = "$Id: pmutil.c,v 2.1 2016/09/26 20:19:30 greg Exp $";
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#endif
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/*
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======================================================================
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Photon map utilities
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Roland Schregle (roland.schregle@{hslu.ch, gmail.com})
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(c) Fraunhofer Institute for Solar Energy Systems,
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(c) Lucerne University of Applied Sciences and Arts,
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supported by the Swiss National Science Foundation (SNSF, #147053)
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======================================================================
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$Id: pmutil.c,v 2.1 2016/09/26 20:19:30 greg Exp $
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*/
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#include "pmap.h"
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#include "pmapio.h"
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#include "pmapbias.h"
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#include "otypes.h"
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#include <sys/stat.h>
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extern char *octname;
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/* Photon map lookup functions per type */
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void (*pmapLookup [NUM_PMAP_TYPES])(PhotonMap*, RAY*, COLOR) = {
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photonDensity, photonPreCompDensity, photonDensity, volumePhotonDensity,
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photonDensity, photonDensity
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};
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void colorNorm (COLOR c)
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/* Normalise colour channels to average of 1 */
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{
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const float avg = colorAvg(c);
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if (!avg)
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return;
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c [0] /= avg;
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c [1] /= avg;
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c [2] /= avg;
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}
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void loadPmaps (PhotonMap **pmaps, const PhotonMapParams *parm)
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{
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unsigned t;
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struct stat octstat, pmstat;
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PhotonMap *pm;
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PhotonMapType type;
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for (t = 0; t < NUM_PMAP_TYPES; t++)
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if (setPmapParam(&pm, parm + t)) {
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/* Check if photon map newer than octree */
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if (pm -> fileName && octname &&
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!stat(pm -> fileName, &pmstat) && !stat(octname, &octstat) &&
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octstat.st_mtime > pmstat.st_mtime) {
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sprintf(errmsg, "photon map in file %s may be stale",
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pm -> fileName);
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error(USER, errmsg);
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}
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/* Load photon map from file and get its type */
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if ((type = loadPhotonMap(pm, pm -> fileName)) == PMAP_TYPE_NONE)
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error(USER, "failed loading photon map");
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/* Assign to appropriate photon map type (deleting previously
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* loaded photon map of same type if necessary) */
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if (pmaps [type]) {
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deletePhotons(pmaps [type]);
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free(pmaps [type]);
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}
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pmaps [type] = pm;
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/* Check for invalid density estimate bandwidth */
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if (pm -> maxGather > pm -> numPhotons) {
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error(WARNING, "adjusting density estimate bandwidth");
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pm -> minGather = pm -> maxGather = pm -> numPhotons;
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}
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}
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}
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void cleanUpPmaps (PhotonMap **pmaps)
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{
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unsigned t;
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for (t = 0; t < NUM_PMAP_TYPES; t++) {
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if (pmaps [t]) {
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deletePhotons(pmaps [t]);
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free(pmaps [t]);
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}
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}
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}
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void photonDensity (PhotonMap *pmap, RAY *ray, COLOR irrad)
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/* Photon density estimate. Returns irradiance at ray -> rop. */
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{
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unsigned i;
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float r;
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COLOR flux;
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Photon *photon;
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const PhotonSearchQueueNode *sqn;
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setcolor(irrad, 0, 0, 0);
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if (!pmap -> maxGather)
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return;
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/* Ignore sources */
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if (ray -> ro && islight(objptr(ray -> ro -> omod) -> otype))
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return;
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findPhotons(pmap, ray);
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/* Need at least 2 photons */
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if (pmap -> squeue.tail < 2) {
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#ifdef PMAP_NONEFOUND
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sprintf(errmsg, "no photons found on %s at (%.3f, %.3f, %.3f)",
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ray -> ro ? ray -> ro -> oname : "<null>",
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ray -> rop [0], ray -> rop [1], ray -> rop [2]);
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error(WARNING, errmsg);
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#endif
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return;
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}
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if (pmap -> minGather == pmap -> maxGather) {
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/* No bias compensation. Just do a plain vanilla estimate */
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sqn = pmap -> squeue.node + 1;
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/* Average radius between furthest two photons to improve accuracy */
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r = max(sqn -> dist2, (sqn + 1) -> dist2);
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r = 0.25 * (pmap -> maxDist2 + r + 2 * sqrt(pmap -> maxDist2 * r));
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/* Skip the extra photon */
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for (i = 1 ; i < pmap -> squeue.tail; i++, sqn++) {
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photon = getNearestPhoton(&pmap -> squeue, sqn -> idx);
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getPhotonFlux(photon, flux);
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#ifdef PMAP_EPANECHNIKOV
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/* Apply Epanechnikov kernel to photon flux based on photon dist */
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scalecolor(flux, 2 * (1 - sqn -> dist2 / r));
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#endif
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addcolor(irrad, flux);
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}
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/* Divide by search area PI * r^2, 1 / PI required as ambient
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normalisation factor */
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scalecolor(irrad, 1 / (PI * PI * r));
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return;
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}
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else
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/* Apply bias compensation to density estimate */
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biasComp(pmap, irrad);
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}
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void photonPreCompDensity (PhotonMap *pmap, RAY *r, COLOR irrad)
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/* Returns precomputed photon density estimate at ray -> rop. */
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{
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Photon p;
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setcolor(irrad, 0, 0, 0);
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/* Ignore sources */
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if (r -> ro && islight(objptr(r -> ro -> omod) -> otype))
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return;
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find1Photon(preCompPmap, r, &p);
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getPhotonFlux(&p, irrad);
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}
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void volumePhotonDensity (PhotonMap *pmap, RAY *ray, COLOR irrad)
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/* Photon volume density estimate. Returns irradiance at ray -> rop. */
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{
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unsigned i;
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float r, gecc2, ph;
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COLOR flux;
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Photon *photon;
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const PhotonSearchQueueNode *sqn;
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setcolor(irrad, 0, 0, 0);
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if (!pmap -> maxGather)
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return;
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findPhotons(pmap, ray);
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/* Need at least 2 photons */
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if (pmap -> squeue.tail < 2)
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return;
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#if 0
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/* Volume biascomp disabled (probably redundant) */
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if (pmap -> minGather == pmap -> maxGather)
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#endif
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{
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/* No bias compensation. Just do a plain vanilla estimate */
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gecc2 = ray -> gecc * ray -> gecc;
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sqn = pmap -> squeue.node + 1;
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/* Average radius between furthest two photons to improve accuracy */
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r = max(sqn -> dist2, (sqn + 1) -> dist2);
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r = 0.25 * (pmap -> maxDist2 + r + 2 * sqrt(pmap -> maxDist2 * r));
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/* Skip the extra photon */
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for (i = 1; i < pmap -> squeue.tail; i++, sqn++) {
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photon = getNearestPhoton(&pmap -> squeue, sqn -> idx);
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/* Compute phase function for inscattering from photon */
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if (gecc2 <= FTINY)
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ph = 1;
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else {
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ph = DOT(ray -> rdir, photon -> norm) / 127;
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ph = 1 + gecc2 - 2 * ray -> gecc * ph;
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ph = (1 - gecc2) / (ph * sqrt(ph));
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}
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getPhotonFlux(photon, flux);
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scalecolor(flux, ph);
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addcolor(irrad, flux);
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}
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/* Divide by search volume 4 / 3 * PI * r^3 and phase function
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normalization factor 1 / (4 * PI) */
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scalecolor(irrad, 3 / (16 * PI * PI * r * sqrt(r)));
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return;
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}
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#if 0
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else
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/* Apply bias compensation to density estimate */
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volumeBiasComp(pmap, ray, irrad);
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#endif
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}
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