Bad render results for Alpha Blend Mode test model

[cdata]

As of #360 , we will be including the Khronos Alpha Blend Mode Test model in our fidelity tests. Unfortunately, <model-viewer> seems to produce incorrect render results in four out of five cases tested by the model:

<model-viewer>	Filament gltf_renderer	Khronos' example

[donmccurdy]

I'm confused by this result – it shows up correctly in my threejs-based viewer: https://gltf-viewer.donmccurdy.com/#model=https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Models/master/2.0/AlphaBlendModeTest/glTF/AlphaBlendModeTest.gltf

[donmccurdy]

Result also looks more correct in the https://truthful-roof.glitch.me demo –

I'm wondering if the scene.clone() call used inside <model-viewer/> has lost some information...

[cdata]

If it's useful, the live test using <model-viewer> is here: https://googlewebcomponents.github.io/model-viewer/test/fidelity/khronos-AlphaBlendModeTest/

It does look like the automation screenshot results in artifacts that are not present in the live render. Screenshot of live render as of now looks like https://truthful-roof.glitch.me:

Still, I think it's fair to say that it is wrong (otherwise we would see more checkmarks).

[donmccurdy]

Agreed! Also possible related: mrdoob/three.js#15483

[cdata]

This was fixed in #423