Implementing light clusters

In this section, we are going to describe our implementation of the light clustering algorithm. It’s based on this presentation: https://www.activision.com/cdn/research/2017_Sig_Improved_Culling_final.pdf. The main (and very smart) idea is to separate the XY plane from the Z range, combining the advantages of both tiling and clustering approaches. The algorithms are organized as follows:

1. We sort the lights by their depth value in camera space.
2. We then divide the depth range into bins of equal size, although a logarithmic subdivision might work better depending on your depth range.
3. Next, we assign the lights to each bin if their bounding box falls within the bin range. We only store the minimum and maximum light index for a given bin, so we only need 16 bits for each bin, unless you need more than 65,535 lights!
4. We then divide the screen into tiles (8x8 pixels, in our case) and determine which lights cover a given tile. Each tile...