I'm trying to create a gltf model with transparency. the model is a simple rectangle / plane, and the file I get from obj2gltf is transparent, but one-sided. that's why I have been using gltf-pipeline with the `--kmc.doubleSided` flag to further process the gltf file in order to make it double-sided. but after that it is not transparent anymore, although the diffuse color is still `1.0, 1.0, 1.0, 0.5`.
what's the right way to do this?