GLTFExporter changing alphaMode

Questions
1

This glTF has a material named Material3 with "alphaMode": "BLEND" but after using glTF exporter the Material3 alphaMode is MASK.

The logic on the exporter is:
if ( material.transparent || material.alphaTest > 0.0 ) {
gltfMaterial.alphaMode = material.opacity < 1.0 ? 'BLEND' : 'MASK';
but looks like it should be:
if ( material.transparent || material.alphaTest > 0.0 ) {
gltfMaterial.alphaMode = 'BLEND';

2

My solution doesn’t work as well as it seems that the glass looks OPAQUE

3

We’ve changed this a few times and don’t have a perfect solution for mapping three<->glTF alpha mode values. But I think something like this might be better:

if ( material.transparent ) {
  gltfMaterial.alphaMode = 'BLEND';
} else if ( material.alphaTest > 0.0 ) {
  gltfMaterial.alphaMode = 'MASK';
}
4

Your solution seems to be working for this specific case.

Thank you @donmccurdy ,your help is much appreciated.