void LDPixelSample(int xPos, int yPos, float shutterOpen,
float shutterClose, int nPixelSamples, Sample *samples, float *buf,
RNG &rng) {
// Prepare temporary array pointers for low-discrepancy camera samples
float *imageSamples = buf;
buf += 2 * nPixelSamples;
float *lensSamples = buf;
buf += 2 * nPixelSamples;
float *timeSamples = buf;
buf += nPixelSamples;
// Prepare temporary array pointers for low-discrepancy integrator samples
uint32_t count1D = samples[0].n1D.size();
uint32_t count2D = samples[0].n2D.size();
const uint32_t *n1D = count1D > 0 ? &samples[0].n1D[0] : NULL;
const uint32_t *n2D = count2D > 0 ? &samples[0].n2D[0] : NULL;
float **oneDSamples = ALLOCA(float *, count1D);
float **twoDSamples = ALLOCA(float *, count2D);
for (uint32_t i = 0; i < count1D; ++i) {
oneDSamples[i] = buf;
buf += n1D[i] * nPixelSamples;
}
for (uint32_t i = 0; i < count2D; ++i) {
twoDSamples[i] = buf;
buf += 2 * n2D[i] * nPixelSamples;
}
// Generate low-discrepancy pixel samples
LDShuffleScrambled2D(1, nPixelSamples, imageSamples, rng);
LDShuffleScrambled2D(1, nPixelSamples, lensSamples, rng);
LDShuffleScrambled1D(1, nPixelSamples, timeSamples, rng);
for (uint32_t i = 0; i < count1D; ++i)
LDShuffleScrambled1D(n1D[i], nPixelSamples, oneDSamples[i], rng);
for (uint32_t i = 0; i < count2D; ++i)
LDShuffleScrambled2D(n2D[i], nPixelSamples, twoDSamples[i], rng);
// Initialize _samples_ with computed sample values
for (int i = 0; i < nPixelSamples; ++i) {
samples[i].imageX = xPos + imageSamples[2*i];
samples[i].imageY = yPos + imageSamples[2*i+1];
samples[i].time = Lerp(timeSamples[i], shutterOpen, shutterClose);
samples[i].lensU = lensSamples[2*i];
samples[i].lensV = lensSamples[2*i+1];
// Copy integrator samples into _samples[i]_
for (uint32_t j = 0; j < count1D; ++j) {
int startSamp = n1D[j] * i;
for (uint32_t k = 0; k < n1D[j]; ++k)
samples[i].oneD[j][k] = oneDSamples[j][startSamp+k];
}
for (uint32_t j = 0; j < count2D; ++j) {
int startSamp = 2 * n2D[j] * i;
for (uint32_t k = 0; k < 2*n2D[j]; ++k)
samples[i].twoD[j][k] = twoDSamples[j][startSamp+k];
}
}
}
bool LDSampler::GetNextSample(Sample *sample) {
if (!oneDSamples) {
// Allocate space for pixel's low-discrepancy sample tables
oneDSamples = new float *[sample->n1D.size()];
n1D = sample->n1D.size();
for (u_int i = 0; i < sample->n1D.size(); ++i)
oneDSamples[i] = new float[sample->n1D[i] *
pixelSamples];
twoDSamples = new float *[sample->n2D.size()];
n2D = sample->n2D.size();
for (u_int i = 0; i < sample->n2D.size(); ++i)
twoDSamples[i] = new float[2 * sample->n2D[i] *
pixelSamples];
}
if (samplePos == pixelSamples) {
// Advance to next pixel for low-discrepancy sampling
if (++xPos == xPixelEnd) {
xPos = xPixelStart;
++yPos;
}
if (yPos == yPixelEnd)
return false;
samplePos = 0;
// Generate low-discrepancy samples for pixel
LDShuffleScrambled2D(1, pixelSamples, imageSamples);
LDShuffleScrambled2D(1, pixelSamples, lensSamples);
LDShuffleScrambled1D(1, pixelSamples, timeSamples);
for (u_int i = 0; i < sample->n1D.size(); ++i)
LDShuffleScrambled1D(sample->n1D[i], pixelSamples,
oneDSamples[i]);
for (u_int i = 0; i < sample->n2D.size(); ++i)
LDShuffleScrambled2D(sample->n2D[i], pixelSamples,
twoDSamples[i]);
}
// Copy low-discrepancy samples from tables
sample->imageX = xPos + imageSamples[2*samplePos];
sample->imageY = yPos + imageSamples[2*samplePos+1];
sample->time = timeSamples[samplePos];
sample->lensU = lensSamples[2*samplePos];
sample->lensV = lensSamples[2*samplePos+1];
for (u_int i = 0; i < sample->n1D.size(); ++i) {
int startSamp = sample->n1D[i] * samplePos;
for (u_int j = 0; j < sample->n1D[i]; ++j)
sample->oneD[i][j] = oneDSamples[i][startSamp+j];
}
for (u_int i = 0; i < sample->n2D.size(); ++i) {
int startSamp = 2 * sample->n2D[i] * samplePos;
for (u_int j = 0; j < 2*sample->n2D[i]; ++j)
sample->twoD[i][j] = twoDSamples[i][startSamp+j];
}
++samplePos;
return true;
}
int BestCandidateSampler::GetMoreSamples(Sample *sample, RNG &rng) {
again:
if (tableOffset == SAMPLE_TABLE_SIZE) {
// Advance to next best-candidate sample table position
tableOffset = 0;
if (++xTile > xTileEnd) {
xTile = xTileStart;
if (++yTile > yTileEnd)
return 0;
}
// Update sample shifts
RNG tileRng(xTile + (yTile<<8));
for (int i = 0; i < 3; ++i)
sampleOffsets[i] = tileRng.RandomFloat();
}
// Compute raster sample from table
#define WRAP(x) ((x) > 1 ? ((x)-1) : (x))
sample->imageX = (xTile + sampleTable[tableOffset][0]) * tableWidth;
sample->imageY = (yTile + sampleTable[tableOffset][1]) * tableWidth;
sample->time = Lerp(WRAP(sampleOffsets[0] + sampleTable[tableOffset][2]),
shutterOpen, shutterClose);
sample->lensU = WRAP(sampleOffsets[1] +
sampleTable[tableOffset][3]);
sample->lensV = WRAP(sampleOffsets[2] +
sampleTable[tableOffset][4]);
// Check sample against crop window, goto _again_ if outside
if (sample->imageX < xPixelStart || sample->imageX >= xPixelEnd ||
sample->imageY < yPixelStart || sample->imageY >= yPixelEnd) {
++tableOffset;
goto again;
}
// Compute integrator samples for best-candidate sample
for (uint32_t i = 0; i < sample->n1D.size(); ++i)
LDShuffleScrambled1D(sample->n1D[i], 1, sample->oneD[i], rng);
for (uint32_t i = 0; i < sample->n2D.size(); ++i)
LDShuffleScrambled2D(sample->n2D[i], 1, sample->twoD[i], rng);
++tableOffset;
return 1;
}
Spectrum SingleScatteringFluorescenceRWLIntegrator::Li(const Scene *scene,
const Renderer *renderer, const RayDifferential &ray,
const Sample *sample, RNG &rng, Spectrum *T, MemoryArena &arena) const {
VolumeRegion *vr = scene->volumeRegion;
float t0, t1;
if (!vr || !vr->IntersectP(ray, &t0, &t1) || (t1-t0) == 0.f) {
*T = 1.f;
return 0.f;
}
// Do single scattering volume integration in _vr_
Spectrum Lv(0.);
// Prepare for volume integration stepping
int nSamples = Ceil2Int((t1-t0) / stepSize);
float step = (t1 - t0) / nSamples;
Spectrum Tr(1.f);
Point p = ray(t0), pPrev;
Vector w = -ray.d;
t0 += sample->oneD[scatterSampleOffset][0] * step;
// Compute sample patterns for single scattering samples
float *lightNum = arena.Alloc<float>(nSamples);
LDShuffleScrambled1D(1, nSamples, lightNum, rng);
float *lightComp = arena.Alloc<float>(nSamples);
LDShuffleScrambled1D(1, nSamples, lightComp, rng);
float *lightPos = arena.Alloc<float>(2*nSamples);
LDShuffleScrambled2D(1, nSamples, lightPos, rng);
uint32_t sampOffset = 0;
for (int i = 0; i < nSamples; ++i, t0 += step) {
// Advance to sample at _t0_ and update _T_
pPrev = p;
p = ray(t0);
Ray tauRay(pPrev, p - pPrev, 0.f, 1.f, ray.time, ray.depth);
Spectrum stepTau = vr->tau(tauRay, 0.5f * stepSize, rng.RandomFloat());
Tr *= Exp(-stepTau);
// Possibly terminate ray marching if transmittance is small
if (Tr.y() < 1e-3) {
const float continueProb = .5f;
if (rng.RandomFloat() > continueProb) {
Tr = 0.f;
break;
}
Tr /= continueProb;
}
// Compute fluorescence emission
Spectrum sigma = vr->Mu(p, w, ray.time);
if (!sigma.IsBlack() && scene->lights.size() > 0) {
int nLights = scene->lights.size();
int ln = min(Floor2Int(lightNum[sampOffset] * nLights),
nLights-1);
Light *light = scene->lights[ln];
// Add contribution of _light_ due to the in-scattering at _p_
float pdf;
VisibilityTester vis;
Vector wo;
LightSample ls(lightComp[sampOffset], lightPos[2*sampOffset],
lightPos[2*sampOffset+1]);
Spectrum L = light->Sample_L(p, 0.f, ls, ray.time, &wo, &pdf, &vis);
if (!L.IsBlack() && pdf > 0.f && vis.Unoccluded(scene)) {
Spectrum Ld = L * vis.Transmittance(scene, renderer, NULL, rng,
arena);
int lambdaExcIndex = light->GetLaserWavelengthIndex();
float Lpower = Ld.GetLaserEmissionPower(lambdaExcIndex);
float yield = vr->Yeild(Point());
Spectrum fEx = vr->fEx(Point());
Spectrum fEm = vr->fEm(Point());
float scale = fEx.GetSampleValueAtWavelengthIndex(lambdaExcIndex);
Lv += Lpower * Tr * sigma * vr->p(p, w, -wo, ray.time) *
scale * fEm * yield * float(nLights) / pdf;
}
}
++sampOffset;
}
*T = Tr;
return Lv * step;
}
void IGIIntegrator::Preprocess(const Scene *scene, const Camera *camera,
const Renderer *renderer) {
if (scene->lights.size() == 0) return;
MemoryArena arena;
RNG rng;
// Compute samples for emitted rays from lights
vector<float> lightNum(nLightPaths * nLightSets);
vector<float> lightSampPos(2 * nLightPaths * nLightSets, 0.f);
vector<float> lightSampComp(nLightPaths * nLightSets, 0.f);
vector<float> lightSampDir(2 * nLightPaths * nLightSets, 0.f);
LDShuffleScrambled1D(nLightPaths, nLightSets, &lightNum[0], rng);
LDShuffleScrambled2D(nLightPaths, nLightSets, &lightSampPos[0], rng);
LDShuffleScrambled1D(nLightPaths, nLightSets, &lightSampComp[0], rng);
LDShuffleScrambled2D(nLightPaths, nLightSets, &lightSampDir[0], rng);
// Precompute information for light sampling densities
Distribution1D *lightDistribution = ComputeLightSamplingCDF(scene);
for (uint32_t s = 0; s < nLightSets; ++s) {
for (uint32_t i = 0; i < nLightPaths; ++i) {
// Follow path _i_ from light to create virtual lights
int sampOffset = s*nLightPaths + i;
// Choose light source to trace virtual light path from
float lightPdf;
int ln = lightDistribution->SampleDiscrete(lightNum[sampOffset],
&lightPdf);
Light *light = scene->lights[ln];
// Sample ray leaving light source for virtual light path
RayDifferential ray;
float pdf;
LightSample ls(lightSampPos[2*sampOffset], lightSampPos[2*sampOffset+1],
lightSampComp[sampOffset]);
Normal Nl;
Spectrum alpha = light->Sample_L(scene, ls, lightSampDir[2*sampOffset],
lightSampDir[2*sampOffset+1],
camera->shutterOpen, &ray, &Nl, &pdf);
if (pdf == 0.f || alpha.IsBlack()) continue;
alpha /= pdf * lightPdf;
Intersection isect;
while (scene->Intersect(ray, &isect) && !alpha.IsBlack()) {
// Create virtual light and sample new ray for path
alpha *= renderer->Transmittance(scene, RayDifferential(ray), NULL,
rng, arena);
Vector wo = -ray.d;
BSDF *bsdf = isect.GetBSDF(ray, arena);
// Create virtual light at ray intersection point
Spectrum contrib = alpha * bsdf->rho(wo, rng) / M_PI;
virtualLights[s].push_back(VirtualLight(isect.dg.p, isect.dg.nn, contrib,
isect.rayEpsilon));
// Sample new ray direction and update weight for virtual light path
Vector wi;
float pdf;
BSDFSample bsdfSample(rng);
Spectrum fr = bsdf->Sample_f(wo, &wi, bsdfSample, &pdf);
if (fr.IsBlack() || pdf == 0.f)
break;
Spectrum contribScale = fr * AbsDot(wi, bsdf->dgShading.nn) / pdf;
// Possibly terminate virtual light path with Russian roulette
float rrProb = min(1.f, contribScale.y());
if (rng.RandomFloat() > rrProb)
break;
alpha *= contribScale / rrProb;
ray = RayDifferential(isect.dg.p, wi, ray, isect.rayEpsilon);
}
arena.FreeAll();
}
}
delete lightDistribution;
}
Spectrum SingleScatteringIntegrator::Li(const Scene *scene, const Renderer *renderer,
const RayDifferential &ray, const Sample *sample,
Spectrum *T, MemoryArena &arena) const {
VolumeRegion *vr = scene->volumeRegion;
float t0, t1;
if (!vr || !vr->IntersectP(ray, &t0, &t1)) {
*T = 1.f;
return 0.f;
}
// Do single scattering volume integration in _vr_
Spectrum Lv(0.);
// Prepare for volume integration stepping
int nSamples = Ceil2Int((t1-t0) / stepSize);
float step = (t1 - t0) / nSamples;
Spectrum Tr(1.f);
Point p = ray(t0), pPrev;
Vector w = -ray.d;
t0 += sample->oneD[scatterSampleOffset][0] * step;
// Compute sample patterns for single scattering samples
float *lightNum = arena.Alloc<float>(nSamples);
LDShuffleScrambled1D(1, nSamples, lightNum, *sample->rng);
float *lightComp = arena.Alloc<float>(nSamples);
LDShuffleScrambled1D(1, nSamples, lightComp, *sample->rng);
float *lightPos = arena.Alloc<float>(2*nSamples);
LDShuffleScrambled2D(1, nSamples, lightPos, *sample->rng);
u_int sampOffset = 0;
for (int i = 0; i < nSamples; ++i, t0 += step) {
// Advance to sample at _t0_ and update _T_
pPrev = p;
p = ray(t0);
Ray tauRay(pPrev, p - pPrev, 0.f, 1.f, ray.time, ray.depth);
Spectrum stepTau = vr->tau(tauRay,
.5f * stepSize, sample->rng->RandomFloat());
Tr *= Exp(-stepTau);
// Possibly terminate ray marching if transmittance is small
if (Tr.y() < 1e-3) {
const float continueProb = .5f;
if (sample->rng->RandomFloat() > continueProb) break;
Tr /= continueProb;
}
// Compute single-scattering source term at _p_
Lv += Tr * vr->Lve(p, w, ray.time);
Spectrum ss = vr->sigma_s(p, w, ray.time);
if (!ss.IsBlack() && scene->lights.size() > 0) {
int nLights = scene->lights.size();
int ln = min(Floor2Int(lightNum[sampOffset] * nLights),
nLights-1);
Light *light = scene->lights[ln];
// Add contribution of _light_ due to scattering at _p_
float pdf;
VisibilityTester vis;
Vector wo;
LightSample ls(lightComp[sampOffset], lightPos[2*sampOffset],
lightPos[2*sampOffset+1]);
Spectrum L = light->Sample_L(p, 0.f, ls, ray.time, &wo, &pdf, &vis);
if (!L.IsBlack() && pdf > 0.f && vis.Unoccluded(scene)) {
Spectrum Ld = L * vis.Transmittance(scene, renderer, NULL, sample->rng, arena);
Lv += Tr * ss * vr->p(p, w, -wo, ray.time) * Ld * float(nLights) / pdf;
}
}
++sampOffset;
}
*T = Tr;
return Lv * step;
}
Spectrum PhotonVolumeIntegrator::Li(const Scene *scene, const Renderer *renderer,
const RayDifferential &ray, const Sample *sample, RNG &rng,
Spectrum *T, MemoryArena &arena) const {
VolumeRegion *vr = scene->volumeRegion;
RainbowVolume* rv = dynamic_cast<RainbowVolume*>(vr);
KdTree<Photon>* volumeMap = photonShooter->volumeMap;
float t0, t1;
if (!vr || !vr->IntersectP(ray, &t0, &t1) || (t1-t0) == 0.f){
*T = 1.f;
return 0.f;
}
// Do single scattering & photon multiple scattering volume integration in _vr_
Spectrum Lv(0.);
// Prepare for volume integration stepping
int nSamples = Ceil2Int((t1-t0) / stepSize);
float step = (t1 - t0) / nSamples;
Spectrum Tr(1.f);
Point p = ray(t0), pPrev;
Vector w = -ray.d;
t0 += sample->oneD[scatterSampleOffset][0] * step;
float *lightNum = arena.Alloc<float>(nSamples);
LDShuffleScrambled1D(1, nSamples, lightNum, rng);
float *lightComp = arena.Alloc<float>(nSamples);
LDShuffleScrambled1D(1, nSamples, lightComp, rng);
float *lightPos = arena.Alloc<float>(2*nSamples);
LDShuffleScrambled2D(1, nSamples, lightPos, rng);
int sampOffset = 0;
ClosePhoton *lookupBuf = new ClosePhoton[nSamples];
for (int i = 0; i < nSamples; ++i, t0 += step) {
// Advance to sample at _t0_ and update _T_
pPrev = p;
p = ray(t0);
Ray tauRay(pPrev, p - pPrev, 0.f, 1.f, ray.time, ray.depth);
Spectrum stepTau = vr->tau(tauRay,.5f * stepSize, rng.RandomFloat());
Tr = Exp(-stepTau);
// Possibly terminate raymarching if transmittance is small.
if (Tr.y() < 1e-3) {
const float continueProb = .5f;
if (rng.RandomFloat() > continueProb){
Tr = 0.f;
break;
}
Tr /= continueProb;
}
// Compute single-scattering source term at _p_ & photon mapped MS
Spectrum L_i(0.);
Spectrum L_d(0.);
Spectrum L_ii(0.);
// Lv += Tr*vr->Lve(p, w, ray.time);
Spectrum ss = vr->sigma_s(p, w, ray.time);
Spectrum sa = vr->sigma_a(p, w, ray.time);
if (!ss.IsBlack() && scene->lights.size() > 0) {
int nLights = scene->lights.size();
int ln =
min(Floor2Int(lightNum[sampOffset] * nLights),
nLights-1);
Light *light = scene->lights[ln];
// Add contribution of _light_ due to scattering at _p_
float pdf;
VisibilityTester vis;
Vector wo;
LightSample ls(lightComp[sampOffset], lightPos[2*sampOffset],
lightPos[2*sampOffset+1]);
Spectrum L = light->Sample_L(p, 0.f, ls, ray.time, &wo, &pdf, &vis);
if (!L.IsBlack() && pdf > 0.f && vis.Unoccluded(scene)) {
Spectrum Ld = L * vis.Transmittance(scene,renderer, NULL, rng, arena);
if(rv){
L_d = rv->rainbowReflection(Ld, ray.d, wo);
}
else {
L_d = vr->p(p, w, -wo, ray.time) * Ld * float(nLights)/pdf;
}
}
}
// Compute 'indirect' in-scattered radiance from photon map
if(!rv){
L_ii += LPhoton(volumeMap, nUsed, lookupBuf, w, p, vr, maxDistSquared, ray.time);
}
// Compute total in-scattered radiance
if (sa.y()!=0.0 || ss.y()!=0.0)
L_i = L_d + (ss/(sa+ss))*L_ii;
else
L_i = L_d;
Spectrum nLv = (sa*vr->Lve(p,w,ray.time)*step) + (ss*L_i*step) + (Tr * Lv) ;
Lv = nLv;
sampOffset++;
}
*T = Tr;
return Lv;
}
void IGIIntegrator::Preprocess(const Scene *scene) {
if (scene->lights.size() == 0) return;
// Compute samples for emitted rays from lights
float *lightNum = new float[nLightPaths * nLightSets];
float *lightSamp0 = new float[2 * nLightPaths * nLightSets];
float *lightSamp1 = new float[2 * nLightPaths * nLightSets];
LDShuffleScrambled1D(nLightPaths, nLightSets, lightNum);
LDShuffleScrambled2D(nLightPaths, nLightSets, lightSamp0);
LDShuffleScrambled2D(nLightPaths, nLightSets, lightSamp1);
// Precompute information for light sampling densities
int nLights = int(scene->lights.size());
float *lightPower = (float *)alloca(nLights * sizeof(float));
float *lightCDF = (float *)alloca((nLights+1) * sizeof(float));
for (int i = 0; i < nLights; ++i)
lightPower[i] = scene->lights[i]->Power(scene).y();
float totalPower;
ComputeStep1dCDF(lightPower, nLights, &totalPower, lightCDF);
for (u_int s = 0; s < nLightSets; ++s) {
for (u_int i = 0; i < nLightPaths; ++i) {
// Follow path _i_ from light to create virtual lights
int sampOffset = s*nLightPaths + i;
// Choose light source to trace path from
float lightPdf;
int lNum = Floor2Int(SampleStep1d(lightPower, lightCDF,
totalPower, nLights, lightNum[sampOffset], &lightPdf) * nLights);
// fprintf(stderr, "samp %f -> num %d\n", lightNum[sampOffset], lNum);
Light *light = scene->lights[lNum];
// Sample ray leaving light source
RayDifferential ray;
float pdf;
Spectrum alpha =
light->Sample_L(scene, lightSamp0[2*sampOffset],
lightSamp0[2*sampOffset+1],
lightSamp1[2*sampOffset],
lightSamp1[2*sampOffset+1],
&ray, &pdf);
if (pdf == 0.f || alpha.Black()) continue;
alpha /= pdf * lightPdf;
// fprintf(stderr, "initial alpha %f, light # %d\n", alpha.y(), lNum);
Intersection isect;
int nIntersections = 0;
while (scene->Intersect(ray, &isect) && !alpha.Black()) {
++nIntersections;
alpha *= scene->Transmittance(ray);
Vector wo = -ray.d;
BSDF *bsdf = isect.GetBSDF(ray);
// Create virtual light at ray intersection point
static StatsCounter vls("IGI Integrator", "Virtual Lights Created"); //NOBOOK
++vls; //NOBOOK
Spectrum Le = alpha * bsdf->rho(wo) / M_PI;
// fprintf(stderr, "\tmade light with le y %f\n", Le.y());
virtualLights[s].push_back(VirtualLight(isect.dg.p, isect.dg.nn, Le));
// Sample new ray direction and update weight
Vector wi;
float pdf;
BxDFType flags;
Spectrum fr = bsdf->Sample_f(wo, &wi, RandomFloat(),
RandomFloat(), RandomFloat(),
&pdf, BSDF_ALL, &flags);
if (fr.Black() || pdf == 0.f)
break;
Spectrum anew = alpha * fr * AbsDot(wi, bsdf->dgShading.nn) / pdf;
float r = anew.y() / alpha.y();
// fprintf(stderr, "\tr = %f\n", r);
if (RandomFloat() > r)
break;
alpha = anew / r;
// fprintf(stderr, "\tnew alpha %f\n", alpha.y());
ray = RayDifferential(isect.dg.p, wi);
}
BSDF::FreeAll();
}
}
delete[] lightNum; // NOBOOK
delete[] lightSamp0; // NOBOOK
delete[] lightSamp1; // NOBOOK
}
