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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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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: pmap.c,v 2.11 2016/05/17 17:39:47 rschregle 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, NULL |
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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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} |
