#379 Grid Spatial Partitioning in OpenCL

[Vasco Alexandre da Silva Costa]

Hello,

This patch adds a simple grid construction algorithm to the ray tracer.

The idea is to implement a ray tracing acceleration structure in ANSI C that can be easily ported to OpenCL later on.

TODO:

• grid traversal.
• port construction and traversal to OpenCL.

[Vasco Alexandre da Silva Costa]

This patch adds grid traversal and a bare bones rendering pipeline.

[Vasco Alexandre da Silva Costa]

Do the grid construction on the GPU side. Added prefix sum (scan) OpenCL kernel.

[Vasco Alexandre da Silva Costa]

This has been replaced with HLBVHs because they make more sense for this application. Closed.