Many changes to jensen.

sphere.cpp

@@ -44,19 +44,7 @@ vec3 Sphere::normal_at_int(Ray & r, float & t) const {
 }
 
 vec3 Sphere::sample_at_surface() const {
-  float theta;
-  float u, sqrt1muu, x, y, z;
-
-  // Sampling formula from Wolfram Mathworld:
-  // http://mathworld.wolfram.com/SpherePointPicking.html
-  theta = random01()* (2.0f * pi<float>());
-  u = (random01() * 2.0f) - 1.0f;
-  sqrt1muu = glm::sqrt(1.0f - (u * u));
-  x = m_radius * sqrt1muu * cos(theta);
-  y = m_radius * sqrt1muu * sin(theta);
-  z = m_radius * u;
-
-  return vec3(x, y, z) + m_center;
+  return sample_sphere(m_center, m_radius);
 }
 
 void Sphere::calculate_inv_area() {