Been working on shadows for local lights for Shade. Still WiP
There are 131 lights in the scene:
1 directional light, which is shadowed with a 3-cascade CSM as before
130 point lights
The system is fairly complex, with all shadows being drawn to the same atlas, including the CSM.
Here’s what the atlas looks like
The lights are scored each frame, and we have a fixed update budget, prioritizing most visible lights that occupy largest area of the screen.
There is a catch-up mechanic, that guarantees that if a light is on-screen, it will eventually be updated.
The second piece of the puzzle is automatic resizing. Lights don’t specify a shadow resolution. Instead - we update resolution each frame… well, not really, but we we allow the resolution for each shadow to change each frame.
So if a light is occupying a very small area of the screen - it gets a very small area in the atlas allocated to it. If the light is not even seen currently - it gets the tiniest area possible - 32x32 in this case.
If you look at the atlas, you’ll be able to notice, there are 5 point lights with 1024 resolution,
a couple with 512,
a handful with 128
and a bunch with 64x64
There’s a one light that happens to be 32x32
And if we move the camera around a bit, the lights that we never seen before get populated as well
There’s a lot of trickery that goes into making this work, but it does work, and it runs pretty well. I’m still going to work on separate render pipeline for local lights to squeeze out extra performance for them, but I’m very happy with the current results.
Theoretically - there is no limit on the number of lights, even if the space in the atlas is always going to be limited.