PBRT_V2 总结记录 BSDFSample 和 BSDFSampleOffsets 和 BSDF::Sample_f() 和BSDF:Pdf

BSDFSample

struct BSDFSample {
   // BSDFSample Public Methods
   BSDFSample(float up0, float up1, float ucomp) {
       Assert(up0 >= 0.f && up0 < 1.f);
       Assert(up1 >= 0.f && up1 < 1.f);
       Assert(ucomp >= 0.f && ucomp < 1.f);
       uDir[0] = up0;
       uDir[1] = up1;
       uComponent = ucomp;
   }
   BSDFSample(RNG &rng) {
      uDir[0] = rng.RandomFloat();
      uDir[1] = rng.RandomFloat();
      uComponent = rng.RandomFloat();
   }
   BSDFSample(const Sample *sample, const BSDFSampleOffsets &offsets, uint32_t num);
   BSDFSample() { }
   float uDir[2], uComponent;
};struct BSDFSample {
   // B