Shadow groups

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Shadows group is a combination of _cs (cast shadows) and _rs (receive shadows) entity keys used to control how entity cast lightmap/vertex light shadows. A numbers should be used for shadows groups (-127 to 127 etc.), negative values are allowed.

Shadows groups are applied during lightmapping of entity using this rules:

1. Receive shadows is 0: object will not receive shadows from anything (occlusion test is skipped)
2. Receive shadows is 1: only receive shadows from objects with cast shadows 1 (the worldspawn cast shadows).
3. Receive shadows is > 1: only receive shadows from objects with same abs(cast shadows) and worldspawn.
4. Receive shadows is < 1: only receive shadows from objects with same abs(cast shadows).

1. Cast shadows is 0: object will not cast any shadows (not included in raytracing tree).
2. Cast shadows is 1: only cast shadows on objects with receive shadows 1 (the worldspawn receive shadows).
3. Cast shadows is > 1: only cast shadows on objects with same abs(receive shadows) and worldspawn.
4. Cast shadows is < 1: only cast shadows on objects with same abs(receive shadows).

By default worldspawn and func_group have cast shadows and receive shadows 1. All other entities have cast shadows 0 and receive shadows 1.

Shadow groups and ambient occlusion

Shadow groups affects the looks of ambient occlusion. Mostly the gain effect (which brightens the edges).

See also

• Lightmap
• Vertex lighting