The main goal of the preprocessing is basically to convert an .obj file into a mesh structure that fits the engine. The whole process takes place in the preprocessing folder. This process can be described in several steps.

1. First, we need to open the .obj file to be able to read it.
2. A first read of the file can now be proceeded. The numbers of vertices and triangles contained in the file need to be figured out and saved it in the new mesh.
3. Given the previous information, the bbox tree architecture of the mesh is easy to make up.
4. The file is then read again. The vertices and Triangles will be added to the mesh during this second reading step.
5. We add the brand new mesh to the world !