[gltf] Use opaque alpha mode by default.

[donmccurdy]

See: KhronosGroup/glTF-Sample-Viewer#20

@takahirox it sounds like transparency in PNGs should be ignored by default, and only applied if the alphaMode is set to something other than OPAQUE.

Before	After

^Fins are should be opaque, in this example, because alphaMode is not set at all, and defaults to OPAQUE.

[mrdoob]

Thanks!

[cx20]

I tried trying the latest version of Three.js + glTF Loader, However, the following error occurred.

THREE.PropertyBinding.sanitizeNodeName is not a function

I think that it is a temporary problem and I want to test it when the main body is rebuilt.

[donmccurdy]

@cx20 The latest change (fixing some animated models created with the Blender exporter) required changes in three.js core. So to test, you'll need the latest version of three.js from the dev branch.

Well, that or a monkeypatch for the issue, THREE.PropertyBinding.sanitizeNodeName = (n) => n;

[cx20]

I was able to confirm the fix by applying the monkeypatch.
Three.js r86dev + glTF Loader result