5001 lights in WebGPU (Shade). 1 directional shadowed light with CSM + 5000 sphere lights. Using clustered lighting, similar to Unreal, the screen is split into tiles of 32x32 pixels and then further split along the Z axis. Lights are culled and binned. Most of the time engines implement... clustered lighting with a fixed number of partitions in XY, something like 40x20, let's say, this is generally fine, but it doesn't adapt to different aspect ratios and tends not to scale as well into higher screen resolutions. Finally, by splitting the XY in 32 pixel increments (or anything that's 2^N really) - you get better wave coherence, that is - pixel shader runs more efficiently. The engine supports up to 10,000 so-called "local lights" in the frame, which can be either be sphere lights (point lights with volume) or spot lights. When I say "in the frame" - I mean on-screen at the same time. There can be a million lights in the scene for example, but only 10,000 can be visible at a time. Can increase the limit, but I reckon 10,000 is already a pretty (un)reasonable limit.show more

Alex Goldring

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