Triplanar Mapping
UV-free projection from three axes
Also known as: Triplanar projection · World-space projection
Definition
Triplanar mapping samples a texture three times — once from each world axis — and blends the results based on the surface normal. It bypasses UVs entirely, which makes it perfect for procedural terrain, large rock formations, and any geometry too complex (or too modular) to unwrap cleanly. The cost is three texture samples per layer instead of one, so it is reserved for surfaces where uniform texel density matters more than that cost.
In production
Houdini and World Machine both export terrain heightfields with no usable UVs at all, so triplanar mapping is the default texturing approach for any terrain shader in Unreal's Landscape system or Unity's Terrain tools — the shader blends X, Y, and Z projections using the surface normal's dot product against each world axis. The main artifact to watch for is visible seams on steep slopes (roughly 45 degrees or more) where the blend between two projections shows a harsh line unless the artist adds noise-based blend sharpness control. Because triplanar mapping ignores the mesh's actual UV channel, it's also the standard fallback for procedurally generated rocks in Houdini pipelines, where re-unwrapping every instance would be impractical. The 3x sample cost per texture layer means a fully triplanar PBR material can run 12 samples instead of 4, so production shaders often blend triplanar only on the far-distance LOD and switch to standard UVs up close.
