bool Cube::samplePosition(PathSampleGenerator &sampler, PositionSample &sample) const
{
float u = sampler.next1D();
int dim = sampleFace(u);
float s = (dim + 1) % 3;
float t = (dim + 2) % 3;
Vec2f xi = sampler.next2D();
Vec3f n(0.0f);
n[dim] = u < 0.5f ? -1.0f : 1.0f;
Vec3f p(0.0f);
p[dim] = n[dim]*_scale[dim];
p[s] = (xi.x()*2.0f - 1.0f)*_scale[s];
p[t] = (xi.y()*2.0f - 1.0f)*_scale[t];
sample.p = _rot*p + _pos;
sample.pdf = _invArea;
sample.uv = xi;
sample.weight = PI*_area*(*_emission)[sample.uv];
sample.Ng = _rot*n;
return true;
}
bool MultiQuadLight::sampleDirect(uint32 threadIndex, const Vec3f &p, PathSampleGenerator &pathSampler, LightSample &sample) const
{
float xi = pathSampler.next1D(EmitterSample);
ThreadlocalSampleInfo &sampler = *_samplers[threadIndex];
std::pair<int, float> result = _sampleBvh->sampleLight(p, &sampler.sampleWeights[0],
&sampler.insideIds[0], xi, [&](uint32 id) {
return approximateQuadContribution(p, id);
});
if (result.first == -1)
return false;
int idx = pathSampler.next1D(EmitterSample) < 0.5f ? result.first*2 : result.first*2 + 1;
const QuadGeometry::TriangleInfo &t = _geometry.triangle(idx);
Vec3f q = SampleWarp::uniformTriangle(pathSampler.next2D(EmitterSample), t.p0, t.p1, t.p2);
Vec3f L = q - p;
float rSq = L.lengthSq();
sample.dist = std::sqrt(rSq);
sample.d = L/sample.dist;
float cosTheta = -(t.Ng.dot(sample.d));
if (cosTheta <= 0.0f)
return false;
sample.pdf = result.second*0.5f*rSq/(cosTheta*_triangleAreas[idx]);
return true;
}
bool IsotropicPhaseFunction::sample(PathSampleGenerator &sampler, const Vec3f &/*wi*/, PhaseSample &sample) const
{
sample.w = SampleWarp::uniformSphere(sampler.next2D());
sample.weight = Vec3f(1.0f);
sample.pdf = SampleWarp::uniformSpherePdf();
return true;
}
bool Quad::sampleDirection(PathSampleGenerator &sampler, const PositionSample &/*point*/, DirectionSample &sample) const
{
Vec3f d = SampleWarp::cosineHemisphere(sampler.next2D(EmitterSample));
sample.d = _frame.toGlobal(d);
sample.weight = Vec3f(1.0f);
sample.pdf = SampleWarp::cosineHemispherePdf(d);
return true;
}
bool Cube::sampleDirection(PathSampleGenerator &sampler, const PositionSample &point, DirectionSample &sample) const
{
Vec3f d = SampleWarp::cosineHemisphere(sampler.next2D());
sample.d = TangentFrame(point.Ng).toGlobal(d);
sample.weight = Vec3f(1.0f);
sample.pdf = SampleWarp::cosineHemispherePdf(d);
return true;
}
bool Quad::samplePosition(PathSampleGenerator &sampler, PositionSample &sample) const
{
Vec2f xi = sampler.next2D(EmitterSample);
sample.p = _base + xi.x()*_edge0 + xi.y()*_edge1;
sample.pdf = _invArea;
sample.uv = xi;
sample.weight = PI*_area*(*_emission)[sample.uv];
sample.Ng = _frame.normal;
return true;
}
bool EquirectangularCamera::sampleDirection(PathSampleGenerator &sampler, const PositionSample &/*point*/, Vec2u pixel,
DirectionSample &sample) const
{
float pdf;
Vec2f uv = (Vec2f(pixel) + 0.5f + _filter.sample(sampler.next2D(), pdf))*_pixelSize;
float sinTheta;
sample.d = uvToDirection(uv, sinTheta);
sample.weight = Vec3f(1.0f);
sample.pdf = INV_PI*INV_TWO_PI/sinTheta;
return true;
}
bool Quad::sampleDirect(uint32 /*threadIndex*/, const Vec3f &p, PathSampleGenerator &sampler, LightSample &sample) const
{
if (_frame.normal.dot(p - _base) <= 0.0f)
return false;
Vec2f xi = sampler.next2D(EmitterSample);
Vec3f q = _base + xi.x()*_edge0 + xi.y()*_edge1;
sample.d = q - p;
float rSq = sample.d.lengthSq();
sample.dist = std::sqrt(rSq);
sample.d /= sample.dist;
float cosTheta = -_frame.normal.dot(sample.d);
sample.pdf = rSq/(cosTheta*_area);
return true;
}
bool PinholeCamera::sampleDirection(PathSampleGenerator &sampler, const PositionSample &/*point*/, Vec2u pixel,
DirectionSample &sample) const
{
float pdf;
Vec2f uv = _filter.sample(sampler.next2D(CameraSample), pdf);
Vec3f localD = Vec3f(
-1.0f + (float(pixel.x()) + 0.5f + uv.x())*2.0f*_pixelSize.x(),
_ratio - (float(pixel.y()) + 0.5f + uv.y())*2.0f*_pixelSize.x(),
_planeDist
).normalized();
sample.d = _transform.transformVector(localD);
sample.weight = Vec3f(1.0f);
sample.pdf = _invPlaneArea/cube(localD.z());
return true;
}
bool CubemapCamera::sampleDirection(PathSampleGenerator &sampler, const PositionSample &/*point*/, Vec2u pixel,
DirectionSample &sample) const
{
Vec2f uv = (Vec2f(pixel) + 0.5f)*_pixelSize;
int face;
if (!uvToFace(uv, face))
return false;
float filterPdf;
uv += _filter.sample(sampler.next2D(CameraSample), filterPdf)*_pixelSize;
sample.d = uvToDirection(face, uv, sample.pdf);
sample.weight = Vec3f(1.0f);
return true;
}
bool HenyeyGreensteinPhaseFunction::sample(PathSampleGenerator &sampler, const Vec3f &wi, PhaseSample &sample) const
{
Vec2f xi = sampler.next2D(MediumPhaseSample);
if (_g == 0.0f) {
sample.w = SampleWarp::uniformSphere(xi);
sample.weight = Vec3f(1.0f);
sample.pdf = SampleWarp::uniformSpherePdf();
} else {
float phi = xi.x()*TWO_PI;
float cosTheta = (1.0f + _g*_g - sqr((1.0f - _g*_g)/(1.0f + _g*(xi.y()*2.0f - 1.0f))))/(2.0f*_g);
float sinTheta = std::sqrt(max(1.0f - cosTheta*cosTheta, 0.0f));
sample.w = TangentFrame(wi).toGlobal(Vec3f(
std::cos(phi)*sinTheta,
std::sin(phi)*sinTheta,
cosTheta
));
sample.weight = Vec3f(1.0f);
sample.pdf = henyeyGreenstein(cosTheta);
}
return true;
}
bool PinholeCamera::sampleDirection(PathSampleGenerator &sampler, const PositionSample &point,
DirectionSample &sample) const
{
Vec2u pixel(sampler.next2D(CameraSample)*Vec2f(_res));
return sampleDirection(sampler, point, pixel, sample);
}