Code clean up and refactoring.

figure.hpp

@@ -6,13 +6,15 @@
 
 #include "ray.hpp"
 
+using glm::vec3;
+
 class Figure {
 public:
   vec3 color;
 
   virtual ~Figure() { }
 
-  virtual bool intersect(Ray & r, float & t) const = 0;
+  virtual bool intersect(Ray & r, float & t, vec3 & n) const = 0;
 
   virtual void set_color(float r, float g, float b) {
     color = vec3(r, g, b);