Texture unit. 
| Enumerator | 
|---|
| Graphic3d_TextureUnit_0  |  | 
| Graphic3d_TextureUnit_1  |  | 
| Graphic3d_TextureUnit_2  |  | 
| Graphic3d_TextureUnit_3  |  | 
| Graphic3d_TextureUnit_4  |  | 
| Graphic3d_TextureUnit_5  |  | 
| Graphic3d_TextureUnit_6  |  | 
| Graphic3d_TextureUnit_7  |  | 
| Graphic3d_TextureUnit_8  |  | 
| Graphic3d_TextureUnit_9  |  | 
| Graphic3d_TextureUnit_10  |  | 
| Graphic3d_TextureUnit_11  |  | 
| Graphic3d_TextureUnit_12  |  | 
| Graphic3d_TextureUnit_13  |  | 
| Graphic3d_TextureUnit_14  |  | 
| Graphic3d_TextureUnit_15  |  | 
| Graphic3d_TextureUnit_BaseColor  | sampler2D occSamplerBaseColor. RGB(A) base color of the material and alpha mask/opacity.  
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| Graphic3d_TextureUnit_Emissive  | sampler2D occSamplerEmissive. RGB emissive map controls the color and intensity of the light being emitted by the material.  
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| Graphic3d_TextureUnit_Occlusion  | sampler2D occSamplerOcclusion. Occlusion map indicating areas of indirect lighting. Encoded into RED channel, with 1.0 meaning no occlusion (full color intensity) and 0.0 complete occlusion (black).  
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| Graphic3d_TextureUnit_Normal  | sampler2D occSamplerNormal. XYZ tangent space normal map.  
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| Graphic3d_TextureUnit_MetallicRoughness  | sampler2D occSamplerMetallicRoughness. Metalness + roughness of the material. Encoded into GREEN (roughness) + BLUE (metallic) channels, so that it can be optionally combined with occlusion texture (RED channel).  
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| Graphic3d_TextureUnit_EnvMap  | samplerCube occSampler0. Environment cubemap for background. Rendered by dedicated program and normally occupies first texture unit.  
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| Graphic3d_TextureUnit_PointSprite  | sampler2D occSamplerPointSprite. Sprite alpha-mask or RGBA image mapped using point UV, additional to BaseColor (mapping using vertex UV). This texture unit is set Graphic3d_TextureUnit_1, so that it can be combined with Graphic3d_TextureUnit_BaseColor, while other texture maps (normal map and others) are unexpected and unsupported for points. Note that it can be overridden to Graphic3d_TextureUnit_0 for FFP fallback on hardware without multi-texturing.  
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| Graphic3d_TextureUnit_DepthPeelingDepth  | sampler2D occDepthPeelingDepth. 1st texture unit for Depth Peeling lookups.  
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| Graphic3d_TextureUnit_DepthPeelingFrontColor  | sampler2D occDepthPeelingFrontColor. 2nd texture unit for Depth Peeling lookups.  
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| Graphic3d_TextureUnit_ShadowMap  | sampler2D occShadowMapSampler. Directional light source shadowmap texture.  
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| Graphic3d_TextureUnit_PbrEnvironmentLUT  | sampler2D occEnvLUT. Lookup table for approximated PBR environment lighting. Configured as index at the end of available texture units - 3.  
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| Graphic3d_TextureUnit_PbrIblDiffuseSH  | sampler2D occDiffIBLMapSHCoeffs. Diffuse (irradiance) IBL map's spherical harmonics coefficients baked for PBR from environment cubemap image. Configured as index at the end of available texture units - 2.  
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| Graphic3d_TextureUnit_PbrIblSpecular  | samplerCube occSpecIBLMap. Specular IBL (Image-Based Lighting) environment map baked for PBR from environment cubemap image. Configured as index at the end of available texture units - 1.  
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