GoKawiilColored Shadow Penumbra
May 2nd, 2026 • 4 min read
Some time ago I saw this effect implemented by Romain Durand on a social media post where the penumbra regions of a light’s shadows would get additional color, known as Colored Penumbra or Colored Shadow Terminator. I really liked the effect and took a stab at it, and now I’m making it available. If you’re curious this Medium article by Shahriar Shahrabi goes through some of the theory.
There’s different ways to go about an implementation and I’ve decided to edit the Engine Shaders for this which (like everything) has pros and cons:
It’s easy, no need to guess which values correspond to light or shadow (as you would with a PostProcess solution) which can be painful with Lumen or day/night cycles
Works with all light types
The implementation is extremely cheap
The color saturation is only configurable across the board (not per light or per scene)
It needs wide penumbras for the effect to be visible
The implementation is only for Dynamic Lights, not Baked
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