By specification of the GLTF default PBR material, one texture can contains as metallic-roughness channels (B and G) and occlusion channel (R).
But occlusion can also be a separate texture. So, to support both scenarios, it's better always use only R-channel of the occlusion texture.
By specification of the GLTF default PBR material, one texture can contains as metallic-roughness channels (B and G) and occlusion channel (R).
But occlusion can also be a separate texture. So, to support both scenarios, it's better always use only R-channel of the occlusion texture.