According to the KHR_materials_specular specification, specularFactor and specularColorFactor should have no affect on metal materials, but metal materials appear significantly darker with a reduced specular factor. Most other rendering engines I've looked at follow this rule.
In the following example, the top row are metal and the bottom row are dielectric, with the left side having specularFactor = 0.15 and the right side at 1.0.
Here is what it looks like in three.js:
Babylon.js:
Maya/Arnold:
Blender (EEVEE):
In all the above examples, the metallic spheres look the same, and there is a visible difference in the dielectric.
I am happy to provide the sample GLTF files if necessary.
According to the KHR_materials_specular specification,
specularFactorandspecularColorFactorshould have no affect on metal materials, but metal materials appear significantly darker with a reduced specular factor. Most other rendering engines I've looked at follow this rule.In the following example, the top row are metal and the bottom row are dielectric, with the left side having
specularFactor = 0.15and the right side at 1.0.Here is what it looks like in three.js:
Babylon.js:
Maya/Arnold:
Blender (EEVEE):
In all the above examples, the metallic spheres look the same, and there is a visible difference in the dielectric.
I am happy to provide the sample GLTF files if necessary.
Thanks.