Metallic-roughness texture

Cesium for Unreal
7

Hi @AndreasRemograph,

I looked into this, and the reason that the metalness in your metallic-roughness texture isn’t working is because your material is defined like this:

    {
      "alphaMode": "OPAQUE",
      "doubleSided": false,
      "emissiveFactor": [0.0, 0.0, 0.0],
      "occlusionTexture": { "index": 3, "texCoord": 1 },
      "pbrMetallicRoughness": {
        "baseColorFactor": [1.0, 1.0, 1.0, 1.0],
        "baseColorTexture": { "index": 2, "texCoord": 0 },
        "metallicFactor": 0.0,
        "metallicRoughnessTexture": { "index": 4, "texCoord": 2 },
        "roughnessFactor": 1.0
      }
  }

That "metallicFactor": 0.0 guarantees that you’ll get a metalness value of 0.0 everywhere, no matter what the texture says. That’s because this factor is multiplied with the value from the texture.

This is explained in the glTF spec:

The value for each property MAY be defined using factors and/or textures (e.g., baseColorTexture and baseColorFactor ). If a texture is not given, all respective texture components within this material model MUST be assumed to have a value of 1.0 . If both factors and textures are present, the factor value acts as a linear multiplier for the corresponding texture values.