GLDECAL

GLDECAL is a computer graphics technique used for applying decals to surfaces in 3D environments. It is commonly implemented in OpenGL applications to create effects such as bullet holes, scorch marks, bloodstains, or other surface details that need to be applied dynamically during runtime. The technique works by rendering a textured polygon with transparency directly onto existing surfaces without modifying the underlying geometry.

GLDECAL functions by temporarily disabling depth testing for the decal polygons while maintaining depth writes, allowing them to properly blend with existing surfaces. This creates the illusion that the decal is part of the original surface. The technique is particularly useful in video games and simulations where dynamic surface markings need to be created without the performance cost of modifying actual geometry.

The implementation typically involves creating textured quads that are positioned precisely on surfaces and oriented to match the surface normal. The texture used for the decal usually contains transparency information to allow proper blending with the underlying surface. GLDECAL is valued for its efficiency and visual effectiveness in creating temporary surface modifications in real-time graphics applications.