Modules of Basic Ray Tracing

Modules 1: Mesh Import. This part is done by CPU

Modules 2: Construct KD-Tree.This module is finished in CPU.

Modules 3: Main part. GPU is responsible for this module. 

Basically each thread is responsible for one ray. 

Step1, Generate rays. 

Step2, find intersections. Kernel functions: 1. KD-Tree search. 2. KD-Restart 3. KD-BackTrack

Step3, calculate colors and reflected refracted rays

Then go to step 2. 

One of the biggest problem is still how to reduce the recursion of module 3. Maybe create a big buffer for every iteration and then add them together. However, this is really memory-consuming.