implemented RENDERER with

  1. Monte Carlo Path Integrator

    1. Unbiased unidirectional integrator

    2. Next event estimation

    3. Multiple Importance Sampling

    4. Russian Roulette path termination
    5. Caustics

    6. Area lights & Soft shadows
    7. BVH acceleration structure

    8. Schlick approximation for Fresnel reflection
  2. Photon Mapping Integrator