cubemaps

Cubemaps are a texture representation used in 3D graphics to encode information about the surrounding environment for a point in space. A cubemap consists of six square textures that form the faces of a cube: +X, -X, +Y, -Y, +Z, and -Z. When sampled with a 3D direction vector, the appropriate face is selected and the corresponding (u,v) coordinates on that face determine the texel color. This enables efficient real-time environment mapping with a single texture lookup per sample.

Cubemaps are used for reflections, specular and diffuse lighting via image-based lighting, skyboxes, and ambient environments. In modern engines, cubemaps are often used with mipmapping and prefiltered variants to support different surface roughness; a set of filtered cubemaps (or a single cubemap with mip levels) can approximate reflection at various roughness levels. Diffuse lighting uses irradiance cubemaps that capture low-frequency lighting.

Creation methods include capturing from the real world with six directional photographs or a cubemap camera, or rendering from a scene by placing a virtual camera at the origin and rendering the six faces. They can be generated from high dynamic range (HDR) panoramas converted to cubemaps. Dynamic cubemaps can be updated at runtime to reflect changes in the scene; some engines construct cubemaps from probes scattered in space.

Advantages include fast lookups, hardware-supported sampling, and reduced distortion compared with spherical textures, making them convenient for directional reflections. Limitations include seams at cube edges, filtering artifacts across faces, higher memory usage compared to a single 2D texture in some cases, and the tendency to represent distant environments rather than local lighting details.