Added direct diffuse lighting.

plane.cpp

@@ -4,17 +4,20 @@
 
 #define TOL 1e-6
 
-using std::abs;
+using std::fabs;
 using glm::dot;
 
-bool Plane::intersect(Ray & r, float & t, vec3 & n) const {
+bool Plane::intersect(Ray & r, float & t) const {
   float d = dot(r.m_direction, m_normal);
 
-  if (abs(d) > TOL) {
+  if (fabs(d) > TOL) {
     t = dot(m_normal, (m_point - r.m_origin)) / d;
-    n = vec3(m_normal);
     return t >= 0.0f;
   }
 
    return false;
 }
+
+vec3 Plane::normal_at_int(Ray & r, float & t) const {
+  return vec3(m_normal);
+}