I used to render GLTF1.0 aircraft models with a minimum of two materials:
- for the fuselage: opaque with my own sort of PBR shading (albedo, normal, specular and environment mapping)
- for windows and windscreen: translucent with environment mapping and specular lighting
Working with GLTF2.0, I see two possible workarounds:
- export models with multiple materials. But if I need to tune anything in the shading (say, I want my aircraft a bit more shinny), I need to re-export all my models. This also implies that I am stuck with the native implementation of PBR.
- use an opacity map (or branching in the fragment shader). But that means everything, opaque or translucent, will have to render in the translucent pass. I am not sure if this would be a problem. This also implies that I rework all textures files and UVs for my models.