The game's decal system is responsible for rendering bullet holes, blood splatter, explosion marks, and other flat textures applied over over BSP surfaces (decals cannot appear on objects). Decal tags describe the appearance and lifetime of these effects.
Decals are most commonly created dynamically from effects, such as explosions and bullet impacts. In these cases, it is recommended to give the decal a maximum lifetime to avoid poor framerates.
Although often created as quads, the game may generate more complex decal meshes to conform to the underlying geometry. Vertices of decal meshes typically stand off from their background with a small margin to avoid Z-fighting, but the distance is not consistent.
Thanks to the following individuals for their research or contributions to this topic:
- Kavawuvi (Invader tag definitions)
- MosesOfEgypt (Tag structure research)