Gi clipmaps - Githubissues

Hello ! This pull request implements voxels global illumination with clipmaps (level of details). The AO module also benefits from the clipmaps. Forum's thread: https://forums.armory3d.org/t/voxel-gi-with-clipmaps/5242

The voxelizer is pretty much the same thing appart that it writes to an image that is 6 times bigger on the x axis to store anisotropy.
A ping-ponging mechanism is used for stability between a shader computing the offset from the previous frame and the temporal shader that will do some extra boundary checks and radiance modification, using data from a simple lighting shader, the environment light, and an extra diffuse bounce.
This temporal compute shader is also responsible for generating the different levels of details and the precomputed datas.
The conetracer has been replaced and doesn't compute cone direction from the normal, instead it has a list of precomputed directions.
The conetracing functions are called inside of compute shaders to avoid unecessary work and the final result from the voxelization is writen on 2D images here before being sampled. This procedure is not possible in forward render and we trace the cones directly.
Specular conetracing uses a dither matrix to tamper with the fact that it only traces one cone.
The extents option has been removed and a new "clipmap count" and "size" option were added. The total extents is now (resolution * voxelSize) ** clipmap_count. The offset option was also removed since there is only once correct value for it.
The voxels refraction is not (re)implemented.
There is SDF (signed distance field) for speculars and voxels shadows ; it's an optimization.

NOTE:

Most of the new shaders come from WickedEngine and are copyrighted, my job was to implement them and keep the same procedure. It offers pretty much the same features (that i've listed above).

BUG:

Environment light doesn't work with forward renderer.

armory3d / armory

Gi clipmaps #3011