00001
00002
00003
00004
00005
00006
00007
00008
00009
00010
00011
00012
00013
00014
00015
00016
00017
00018
00019
00020
00021
00022
00023
00024
00025 #include "volume.h"
00026
00027 class HomogeneousVolume : public VolumeRegion {
00028 public:
00029
00030 HomogeneousVolume(const Spectrum &sa, const Spectrum &ss, float gg,
00031 const Spectrum &emit, const BBox &e,
00032 const Transform &v2w) {
00033 WorldToVolume = v2w.GetInverse();
00034 sig_a = sa;
00035 sig_s = ss;
00036 g = gg;
00037 le = emit;
00038 extent = e;
00039 }
00040 BBox WorldBound() const {
00041 return WorldToVolume.GetInverse()(extent);
00042 }
00043 bool IntersectP(const Ray &r, float *t0, float *t1) const {
00044 Ray ray = WorldToVolume(r);
00045 return extent.IntersectP(ray, t0, t1);
00046 }
00047 Spectrum sigma_a(const Point &p, const Vector &) const {
00048 return extent.Inside(WorldToVolume(p)) ? sig_a : 0.;
00049 }
00050 Spectrum sigma_s(const Point &p, const Vector &) const {
00051 return extent.Inside(WorldToVolume(p)) ? sig_s : 0.;
00052 }
00053 Spectrum sigma_t(const Point &p, const Vector &) const {
00054 return extent.Inside(WorldToVolume(p)) ? (sig_a + sig_s) : 0.;
00055 }
00056 Spectrum Lve(const Point &p, const Vector &) const {
00057 return extent.Inside(WorldToVolume(p)) ? le : 0.;
00058 }
00059 float p(const Point &p, const Vector &wi, const Vector &wo) const {
00060 if (!extent.Inside(WorldToVolume(p))) return 0.;
00061 return PhaseHG(wi, wo, g);
00062 }
00063 Spectrum Tau(const Ray &ray, float, float) const {
00064 float t0, t1;
00065 if (!IntersectP(ray, &t0, &t1)) return 0.;
00066 return Distance(ray(t0), ray(t1)) * (sig_a + sig_s);
00067 }
00068 private:
00069
00070 Spectrum sig_a, sig_s, le;
00071 float g;
00072 BBox extent;
00073 Transform WorldToVolume;
00074 };
00075
00076 extern "C" DLLEXPORT VolumeRegion *CreateVolumeRegion(const Transform &volume2world,
00077 const ParamSet ¶ms) {
00078
00079 Spectrum sigma_a = params.FindOneSpectrum("sigma_a", 0.);
00080 Spectrum sigma_s = params.FindOneSpectrum("sigma_s", 0.);
00081 float g = params.FindOneFloat("g", 0.);
00082 Spectrum Le = params.FindOneSpectrum("Le", 0.);
00083 Point p0 = params.FindOnePoint("p0", Point(0,0,0));
00084 Point p1 = params.FindOnePoint("p1", Point(1,1,1));
00085 return new HomogeneousVolume(sigma_a, sigma_s, g, Le, BBox(p0, p1),
00086 volume2world);
00087 }