/// material.h// ----------------------------------------------------- // [author]        lv // [begin ]        2018.1.1 // [brief ]        the material-class for the ray-tracing project //                from the 《ray tracing in one week》 // ----------------------------------------------------- #ifndef MATERIAL_H #define MATERIAL_Hnamespace rt {  //abstract basic classclass material     { public:      /*     @brief: produce a scattered ray     @param: InRay -> Incident light             info -> the information of intersect-point(hit-point)             attenuation -> when scattered, how much the ray should be attenuated by tis reflectance R             scattered -> as we talk, it is a new sight; or                          it is the scattered ray with the intersect-point     @retur: the function calculate a scattered ray or not     */    virtual bool scatter(const ray& InRay, const hitInfo& info, rtvec& attenuation, ray& scattered)const = 0;  protected:      /*     @brief: find a random point in unit_sphere     */    const rtvec random_unit_sphere()const         {         rtvec p;         do             {             p = 2.0*rtvec(rtrand01(), rtrand01(), rtrand01()) - rtvec(1, 1, 1);             } while (dot(p, p) >= 1.0);         return p;         }      };  }  #endif