Shadow groups
From Blood Wiki
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. Blood map allows shadow groups from -127 to 127.
Shadows groups are applied during lightmapping of entity using this rules:
- Receive shadows is 0: object will not receive shadows from anything (occlusion test is skipped)
- Receive shadows is 1: only receive shadows from objects with cast shadows 1 (the worldspawn cast shadows).
- Receive shadows is > 1: only receive shadows from objects with same abs(cast shadows) and worldspawn.
- Receive shadows is < 1: only receive shadows from objects with same abs(cast shadows).
- Cast shadows is 0: object will not cast any shadows (not included in raytracing tree).
- Cast shadows is 1: only cast shadows on objects with receive shadows 1 (the worldspawn receive shadows).
- Cast shadows is > 1: only cast shadows on objects with same abs(receive shadows) and worldspawn.
- 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.