Decal

A decal is a shader that's projected onto something else. Commonly used for blood splatter on walls, or bullet holes. Depending on the rendersystem of the engine the decal can do varying things. At the very least, it can draw a texture on top of things. However, it can often also use and modify the content it projects onto. Things like normal and roughness can be affected.

A common issue with decals is the fact that they are projected and are therefore prone to stretching. There are various methods of getting around this. They include angle fading or projecting from multiple angles.