Added extinction coefficient

src/ray.cpp

@@ -46,3 +46,7 @@ int ray::get_source() const{
 double ray::get_amplitude() const{
   return amplitude;
 }
+
+double ray::get_amplitude_at(double t) const{
+  return amplitude*std::exp(-12600.*extinction_coeff*(at(t) - orig).length());
+}

src/ray.hpp

@@ -6,7 +6,7 @@
 class ray{
 public:
   ray();
-  ray(const point3& origin, const vec3& direction, double amplitude, double opl, double refractive_index, int phase_flips, int max_bounces);
+  ray(const point3& origin, const vec3& direction, double amplitude, double opl, double refractive_index, double extinction_coeff, int phase_flips, int max_bounces);
 
   point3 origin() const;
   vec3 direction() const;
@@ -22,12 +22,14 @@ public:
   int get_source() const;
 
   double get_amplitude() const;
+  double get_amplitude_at(double t) const;
 
 private:
   point3 orig;
   vec3 dir;
   double optical_path; //optical path since pixel
   double refractive_index; //refractive index of next straight path
+  double extinction_coeff; //extinction coeff of next straight path
   int phase_flips; //number of phase flips accumulated so far (from refl.)
   int source; //information about the source the ray ended at (0 for none)
   int bounces_left; //number of bounces the ray can perform