光照计算
暂时只加入了点光源
//点光源
class PointLight :public Light
{
public:
//衰减系数
double kc;
double kl;
double kq;
Color CalculateColor(const Vertex3D &vertex, const Material &material, const Point3D &objectPos)
{
//计算环境光
double r = material.ra.r;
double g = material.ra.g;
double b = material.ra.b;
//计算散射光
Vector3D l = position- vertex.vertex<