AnimatedTriangle.gltf does not rotate correctly

[cx20]

Describe the bug I tried to create a display sample of glTF model by filament v1.4.0 with gltf-test. However, the model does not seem to rotate as expected.

To Reproduce glTF/AnimatedTriangle.gltf + filament result:

Expected behavior

This model is expected to rotate seamlessly. https://github.com/KhronosGroup/glTF-Tutorials/blob/master/gltfTutorial/gltfTutorial_006_SimpleAnimation.md

Desktop (please complete the following information):

• OS: Windows 10 + Chrome 77
• GPU: Intel HD Graphics 520
• Backend: WebGL/ANGLE (Intel(R) HD Graphics 520 Direct3D11 vs_5_0 ps_5_0)

[prideout]

Thanks! This is probably occurring in the last .25 seconds, when we slerp between the last quat and the first quat -- we aren't taking the shortest path between these two orientations.

This is my fault: when I fixed a NaN issue, I probably broke this corner case. We take an abs at the top of our slerp implementation, which obviates the check at the bottom. Will fix and add a unit test.

[cx20]

Thanks, I have confirmed that AnimatedTriangle.gltf rotates correctly with the latest version of Filament. glTF/AnimateTriangle.gltf + filament result:

I updated the status of gltf-test.