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Multi-Texture describes the blending of multiple textures on the same surface.

Texture Splatting

Texture splatting is a method for blending multiple textures together on the same mesh, by painting a mask between them. Often Vertex Color is used to control the blending because vertex color is fairly cheap. Or a bitmap can be used (splat map) because it gives more control and avoids the gradient artifacts of vertex blending.

Modulation Blending

This method adds sharp details to the blend area, by mixing vertex color (for the larger blend) with grayscale textures (for the sharp detail blend). These grayscale maps are either stored in the alpha channel of each layer's normal map, or multiple maps can be channel packed into a single map. Usually the shader has a control for how sharp the transition will be, and sometimes you can use a vertex color or bitmap to control the sharpness.

Variation Blending

Methods for adding variation across a tiling texture.

Trim Sheets

Trim sheet is a few textures packed into one bitmap. Often the textures tile horizontally or vertically, however there's no requirement for anything to tile. Trim sheets often use channel packing.

- texturing techniques of Sunset Overdrive by Morten Olsen, Principal Environment Artist, Insomniac Games, at GDC 2015.

Two channel packed trim sheets, which store a total of six unique textures, see An exercise in modular textures - Scifi lab UDK on the Polycount Forum. Image by Tor 'Snefer' Frick.

A channel packed trim sheet used to texture an entire scene, see [UDK Oil Rig Observation Outpost] on the Polycount Forum. Image by Wiktor 'Disting' Öhman.

A channel packed trim sheet used in Mass Effect 3, see Mass Effect 3 art - Marc-Antoine Hamelin on the Polycount Forum. Image by Marc-Antoine 'Marcan' Hamelin.

Blending Operations

When blending textures together, usually the surface's color (source) is combined with the background color (destination) in a linear way. This is similar to the "Normal" blending mode in Photoshop. However there are many other blending methods available... Add, Multiply, Overlay, etc.


id Software's Megatexture tech uses Decals and multitexturing to create their terrain textures, which are then baked down in a preprocessing step into a huge texture sheet, that's dynamically loaded as you play the game. So it's not really multitexturing in the end, blending in real-time, instead it's a single colormap baked from a multitextured source. The Splash Damage wiki has an article about generating Megatextures for ETQW.

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