The TerrainMaterialLayer renders a material, such as grass, dirt, rocks, etc., onto the terrain.

Material textures:
The material is defined by several tiling textures:

• DiffuseTexture
• SpecularTexture
• NormalTexture
• HeightTexture

Blend texture:
The BlendTexture contains blend weights. It is a non-tiling texture which covers the terrain tile. (In other tools or engines this texture is called splat map, control map, alpha map, material map, weight map, or mask texture.) A blend texture can contain several blend weights (e.g. an RGBA texture can contain 4 blend weights - one weight per channel). The property BlendTextureChannel determines which channel is used by the material layer.

The material reads the blend weight from the blend texture and if the blend weight is greater than BlendThreshold, the material is drawn. There is a small transition zone around the threshold where the material fades out. This transition zone is defined by BlendRange.

The HeightTexture of the material can be used to modify the blending. This can be used to create more realistic transitions between two materials. For example: One material layer draws a dirt texture. The next material layer blends a stone texture over the dirt texture. The stone material includes a height texture. This is used to create a dirt-stone transition where more dirt is visible in the gaps between stones (low height values). BlendHeightInfluence controls how much the height texture influences the blending.

Noise can also be used to make transitions between two material layers visually more interesting. If BlendNoiseInfluence is greater than 0, a noise value is added to the blend weight to make transitions less uniform. NoiseTileSize controls the size of the tiling noise texture.

Tint texture:
The TintTexture contains a color that is multiplied with the material. Like the BlendTexture, the TintTexture is a non-tiling texture which covers the entire terrain tile. TintStrength defines the influence of the TintTexture.

Height-based and slope-based blending based:
The properties TerrainHeightMin, TerrainHeightMax, TerrainSlopeMin, and TerrainSlopeMax can be used to apply the material only on terrain geometry with a certain height or slope. Near these limits the material fades out. The fade-out range is determined by TerrainHeightBlendRange and TerrainSlopeBlendRange.

Triplanar texture mapping:
The material textures are usually projected top-down onto the material. This may lead to distorted textures on very steep slopes. Triplanar texture mapping can be used to reduce distortions. If the triplanar texturing is enabled, the terrain normals are checked and the texture is projected vertically (y direction) or horizontally (x or z direction) to minimize distortions.

Triplanar texture mapping is disabled by default (TriplanarTightening = -1). Set TriplanarTightening to a positive value, e.g. 0.5, to enable triplanar texturing. Larger TriplanarTightening values make the transitions between different projection directions shorter.

Reference