Add material support

hittable.hpp

@@ -1,21 +1,8 @@
 #ifndef HITTABLE_H
 #define HITTABLE_H
 
-#include "ray.hpp"
-
-/* Representation of a hitpoint of a ray against a hittable object */
-struct hit_record {
-    point3 p;
-    vec3 normal;
-    double t;
-    bool front_face;
-
-    inline void set_face_normal(const ray& r, const vec3& outward_normal)
-    {
-        front_face = dot(r.direction, outward_normal) < 0;
-        normal = front_face ? outward_normal : -outward_normal;
-    }    
-};
+#include "rtweekend.hpp"
+#include "material.hpp"
 
 /* Virtual class that represents objects who could collide against a ray */
 struct hittable {