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85 lines
1.6 KiB
C++
85 lines
1.6 KiB
C++
// This code is in the public domain -- castanyo@yahoo.es
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#ifndef NV_MATH_MONTECARLO_H
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#define NV_MATH_MONTECARLO_H
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#include <nvmath/Vector.h>
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#include <nvmath/Random.h>
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namespace nv
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{
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/// A random sample distribution.
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class SampleDistribution
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{
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public:
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// Sampling method.
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enum Method {
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Method_Random,
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Method_Stratified,
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Method_NRook
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};
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// Distribution functions.
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enum Distribution {
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Distribution_Uniform,
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Distribution_Cosine
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};
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/// Constructor.
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SampleDistribution(int num)
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{
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m_sampleArray.resize(num);
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}
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void redistribute(Method method=Method_NRook, Distribution dist=Distribution_Cosine);
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/// Get parametric coordinates of the sample.
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Vector2 sample(int i) { return m_sampleArray[i].uv; }
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/// Get sample direction.
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Vector3 sampleDir(int i) { return m_sampleArray[i].dir; }
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/// Get number of samples.
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uint sampleCount() const { return m_sampleArray.count(); }
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private:
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void redistributeRandom(const Distribution dist);
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void redistributeStratified(const Distribution dist);
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void multiStageNRooks(const int size, int* cells);
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void redistributeNRook(const Distribution dist);
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/// A sample of the random distribution.
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struct Sample
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{
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/// Set sample given the 3d coordinates.
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void setDir(float x, float y, float z) {
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dir.set(x, y, z);
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uv.set(acosf(z), atan2f(y, x));
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}
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/// Set sample given the 2d parametric coordinates.
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void setUV(float u, float v) {
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uv.set(u, v);
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dir.set(sinf(u) * cosf(v), sinf(u) * sinf(v), cosf(u));
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}
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Vector2 uv;
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Vector3 dir;
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};
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/// Random seed.
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MTRand m_rand;
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/// Samples.
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Array<Sample> m_sampleArray;
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};
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} // nv namespace
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#endif // NV_MATH_MONTECARLO_H
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