Building the orange, in eight steps:
  1. Just trace a ray to the sphere
  2. Compute the surface normal
  3. Lambertian diffuse shading
  4. Ambient and diffuse components of Phong shading
  5. Add Specular component of Phong shading
  6. Multiple light sources (arrays)
  7. Material color procedural texture
  8. Bump map procedural texture