all games: Fix a case of dynamic shadows bleeding through thin surfaces #1686
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ficool2
reviewed
Dec 2, 2025
I presume, in layman's terms, this means that improper shadows which are in the direction of the shadow will still appear, like so?
(note shadows at crosshair) |
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Yes. Though if Valve were to raise the limit of clip planes it would've been possible to fix this a similar way to this PR. |
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Description
CClientShadowMgr::ComputeExtraClipPlanesbuilds clip planes from the shadow bounding box corner farthest along the shadow direction to prevent dynamic shadows poking through surfaces.If that corner ends up inside or goes through a brush it would cause the shadow to render on the other side of the brush's surface. This can happen when a model stands near a thin brush wall.
To fix this, this PR updates the compute routine to do a trace from the renderable's origin to the bounding box corner and push the corner's origin along the surface normal away from the brush towards the renderable if needed.
Note that this doesn't address the lack of dynamic shadow clipping through walls in the shadow direction because of the engine's hard-coded limit of max 4 clip planes per shadow. If the limit were to be incremented by 3 (1 plane for each axis) it would suffice to provide a fix for that.
Comparison screenshots of some problematic spots on Dustbowl:
Closes ValveSoftware/Source-1-Games#52