ThreeJS texture splatting class with diffuse, normal and ORM (ambient occlusion/roughness/metalness) maps.
The SplatterManager class creates a new standard material with texture splatting. The shader is modified using onBeforeCompile to create the splats in one shader.
4 textures are blended together using a mixmap texture. The mixmap blends textures like this:
- red channel mixes textures 1 and 2.
- green channel mixes textures 3 and 4.
- blue channel mixes red and green.
Blended textures have their own diffuseMap, normalMap and ORM maps.
ORM maps contain the following:
- red channel - ambient occlusion
- green channel - roughness map
- blue channel - metalness map
Any texture can be mixed with any other textures without restriction.
This table shows how the mixmap colors relate to a specific texture at any given point:
| Material | mixmap1 color |
|---|---|
| 1 | black #000000 |
| 2 | red #FF0000 |
| 3 | blue #0000FF |
| 4 | cyan #00FFFF |
The file SplatterManager_7_materials_normal_diffuse.js contains a version that combines
7 different diffuse and normal maps, no ORM map, and 2 mix maps, as follows:
mix map 1:
- R1 -> textures 1 + 2
- G1 -> textures 3 + 4
- B1 -> R1 + G1
mix map 2:
- R2 -> textures 5 + 6
- G2 -> texture 7 + R2
- B2 -> G2 + B1
This table shows how the mixmap colors must be configured in order for the shader material to show a specific texture at any given point:
| Material | mixmap1 color | mixmap2 color |
|---|---|---|
| 1 | black #000000 | blue #0000FF |
| 2 | red #FF0000 | blue #0000FF |
| 3 | blue #0000FF | blue #0000FF |
| 4 | cyan #00FFFF | blue #0000FF |
| 5 | (any) | green #00FF00 |
| 6 | (any) | yellow #FFFF00 |
| 7 | (any) | black #000000 |
This shader variant does not include ORM maps because for some GPU's, renderer.capabilities.maxTextures yields 16, which means no more than 16 textures can be used in a single shader. Exceeding this limit can result in the following error:
Program Info Log: FRAGMENT shader texture image units count exceeds MAX_TEXTURE_IMAGE_UNITS(16)
For maximum compatibility, ORM maps have been dropped to meet the 16 texture limit and avoid this error.
Since 7 pseudo-materials with one diffuse and one normal is 14 textures, plus 2 mixmaps means all 16 textures are used.
This image shows 7 textures combined into a single shader with all possible blending combinations.
