PBRT_V2 总结记录 ShapeSet

class ShapeSet {
public:
    // ShapeSet Public Methods
    ShapeSet(const Reference<Shape> &s);
    float Area() const { return sumArea; }
    ~ShapeSet();
    Point Sample(const Point &p, const LightSample &ls, Normal *Ns) const;
    Point Sample(const LightSample &ls, Normal *Ns) const;
    float Pdf(const Point &p, const Vector &wi) const;
    float Pdf(const Point &p) const;
private:
    // ShapeSet Private Data
    vector<Reference<Shape> > shapes;
    float sumArea;
    vector<float> areas;
    Distribution1D *areaDistribution;
};class ShapeSet {
public:
    // ShapeSet