Post
Projecting detail textures like bullet holes, blood splatters, and cracks onto existing surfaces without modifying the underlying geometry.
Decals are textures projected onto surfaces in the game world to add dynamic or contextual detail. When you shoot a wall and a bullet hole appears, that is a decal projected onto the wall surface. When blood splatters during combat, tire marks appear on a road, or graffiti decorates a building, decals are at work. Modern deferred decal systems project a box volume into the scene and stamp the decal's texture onto whatever geometry falls within that volume, correctly wrapping around corners and edges. Decals can modify not just color but also normal maps and roughness, making a wet splash on a dry floor actually look wet and reflective rather than just a flat texture overlay.
Example
Doom Eternal's decal system is exceptionally detailed, with demon wounds showing exposed flesh, bone, and gore that dynamically appear as you damage enemies. The damage model looks so good because decals modify the demon's normal maps and PBR properties, not just their color. Control uses decals extensively for its destructive environments, with bullet impacts, concrete chips, and paper debris accumulating on surfaces during firefights. Left 4 Dead 2's blood decals became iconic, with levels gradually transforming from clean to gore-covered as players fought through hordes.
Why it matters
Decals are the visual feedback layer that makes game worlds feel responsive to player actions. Without them, shooting a wall would leave no mark, explosions would leave no scorch, and combat would feel disconnected from the environment. They are a low-cost way to make static environments feel dynamic and lived-in, and their quality significantly impacts how satisfying moment-to-moment gameplay feels.
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