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#include "Sampler.h"
namespace SyntopiaCore {
namespace GLEngine {
Sampler::Sampler(Math::RandomNumberGenerator* rg) : rg(rg) {
}
Sampler::~Sampler() {
}
namespace {
// This code is based on the method in Physical Based Rendering p. 666, and the Sunflow implementation
Vector3f concentricSampleDisk(float u1, float u2) {
float r, angle;
float sx = 2 * u1 - 1;
float sy = 2 * u2 - 1;
if (sx == 0.0 && sy == 0.0) return Vector3f(0,0,0);
if (sx >= -sy) {
if (sx > sy) {
r = sx;
if (sy > 0.0) angle = sy/r; else angle = 8.0f + sy/r;
}
else {
r = sy;
angle = 2.0f - sx/r;
}
}
else {
if (sx <= sy) {
r = -sx;
angle = 4.0f - sy/r;
}
else {
r = -sy;
angle = 6.0f + sx/r;
}
}
angle *= 3.1415 / 4.f;
return Vector3f(r * cosf(angle),r * sinf(angle),0);
}
}
Vector3f StratifiedSampler::getAODirection(int index) {
if (index>=aoSamples.count()) throw 1;
return aoSamples[index];
}
Vector3f StratifiedSampler::getAASample(int index) {
if (index>=aaSamples.count()) throw 1;
return aaSamples[index];
}
Vector3f StratifiedSampler::getLensSample(int index) {
if (index>=lensSamples.count()) throw 1;
return lensSamples[index];
}
// Based on the Physical Based Rendering book
Vector3f StratifiedSampler::sampleSphere(double u1, double u2) {
double z = 1.0 - 2.0*u1;
double r = 0;
if (1.0-z*z > 0) r = sqrt(1.0-z*z);
double phi = 2.0 * 3.1415926 * u2;
double x = r * cos(phi);
double y = r * sin(phi);
return Vector3f(x,y,z);
}
void StratifiedSampler::prepareSamples(int nAASamplesSqrt, int nAOSamplesSqrt) {
int nSqrt = nAASamplesSqrt*nAOSamplesSqrt;
aoSamples = QVector<Vector3f>(nSqrt*nSqrt);
aaSamples = QVector<Vector3f>(nAASamplesSqrt*nAASamplesSqrt);
lensSamples = QVector<Vector3f>(nAASamplesSqrt*nAASamplesSqrt);
int count = 0;
for (int i = 0; i < nSqrt; i++) {
for (int j = 0; j < nSqrt; j++) {
// we need a uniform number in the interval
// [i/nSqrt;(i+1)/nSqrt]
double x = rg->getDouble( ((double)i)/(double)nSqrt,((double)(i+1.0))/(double)nSqrt);
double y = rg->getDouble( ((double)j)/(double)nSqrt,((double)(j+1.0))/(double)nSqrt);
aoSamples[count++] = sampleSphere(x,y);
}
}
count = 0;
for (int i = 0; i < nAASamplesSqrt; i++) {
for (int j = 0; j < nAASamplesSqrt; j++) {
// we need a uniform number in the interval
// [i/nSqrt;(i+1)/nSqrt]
double x = rg->getDouble( ((double)i)/(double)nAASamplesSqrt,((double)(i+1.0))/(double)nAASamplesSqrt);
double y = rg->getDouble( ((double)j)/(double)nAASamplesSqrt,((double)(j+1.0))/(double)nAASamplesSqrt);
aaSamples[count] = Vector3f(x-0.5,y-0.5,1);
x = rg->getDouble( ((double)i)/(double)nSqrt,((double)(i+1.0))/(double)nSqrt);
y = rg->getDouble( ((double)j)/(double)nSqrt,((double)(j+1.0))/(double)nSqrt);
lensSamples[count++] = concentricSampleDisk(x,y);
}
}
// We randomize the samples to avoid coherence.
aaSamples = rg->randomize(aaSamples);
lensSamples = rg->randomize(lensSamples);
};
/// --- Progressive versions...
Vector3f ProgressiveStratifiedSampler::getAODirection(int index) {
if (index>=aoSamplesSqrt*aoSamplesSqrt) throw 1;
int j = index / aoSamplesSqrt;
int i = index % aoSamplesSqrt;
double x = rg->getDouble( ((double)i)/(double)aoSamplesSqrt,((double)(i+1.0))/(double)aoSamplesSqrt);
double y = rg->getDouble( ((double)j)/(double)aoSamplesSqrt,((double)(j+1.0))/(double)aoSamplesSqrt);
return sampleSphere(x,y);
}
Vector3f ProgressiveStratifiedSampler::getAASample(int ix) {
if (ix>=(aaSamplesSqrt*aaSamplesSqrt)) throw 1;
int index = (aaSamplesSqrt*aaSamplesSqrt-1)-aaOrder[ix];
int i = index / aaSamplesSqrt;
int j = index % aaSamplesSqrt;
double x = rg->getDouble( ((double)i)/(double)aaSamplesSqrt,((double)(i+1.0))/(double)aaSamplesSqrt);
double y = rg->getDouble( ((double)j)/(double)aaSamplesSqrt,((double)(j+1.0))/(double)aaSamplesSqrt);
return Vector3f(x-0.5,y-0.5,1);
}
Vector3f ProgressiveStratifiedSampler::getLensSample(int ix) {
if (ix>=(aaSamplesSqrt*aaSamplesSqrt)) throw 1;
int index = aaOrder[ix];
int i = index / aaSamplesSqrt;
int j = index % aaSamplesSqrt;
double x = rg->getDouble( ((double)i)/(double)aaSamplesSqrt,((double)(i+1.0))/(double)aaSamplesSqrt);
double y = rg->getDouble( ((double)j)/(double)aaSamplesSqrt,((double)(j+1.0))/(double)aaSamplesSqrt);
//return rg->getUniform2D();
return concentricSampleDisk(x,y);
}
// Based on the Physical Based Rendering book
Vector3f ProgressiveStratifiedSampler::sampleSphere(double u1, double u2) {
double z = 1.0 - 2.0*u1;
double r = 0;
if (1.0-z*z > 0) r = sqrt(1.0-z*z);
double phi = 2.0 * 3.1415926 * u2;
double x = r * cos(phi);
double y = r * sin(phi);
return Vector3f(x,y,z);
}
void ProgressiveStratifiedSampler::prepareSamples(int nAASamplesSqrt, int nAOSamplesSqrt) {
this->aoSamplesSqrt = nAASamplesSqrt*nAOSamplesSqrt;
this->aaSamplesSqrt = nAASamplesSqrt;
};
Sampler* ProgressiveStratifiedSampler::clone(Math::RandomNumberGenerator* rg) {
ProgressiveStratifiedSampler* ps = new ProgressiveStratifiedSampler(rg);
ps->aaOrder = aaOrder;
return ps;
}
}
}
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