Edit: Somewhat different issue, but I’m also seeing a rotation discrepancy in the image based lighting between the sandbox (4.1.0-beta.23) and the Babylon previewer in VS Code (4.0.3). One appears to be using leftHanded rotation, the other right handed. Would using Babylon through these different systems have different defaults? I’m also seeing fairly different behavior between the two versions for irradiance.
I found an issue where the skybox and the reflection texture on the model were different. The skybox was applying it’s reflection matrix twice and we have fixed this problem.
Here is the test model I’ve been using: DebugEnvironment.zip (329.5 KB)
I will put this up on GitHub after I clean it up a bit. I purposefully changed the IBL rotation to rotate around Y by 180 degrees.
As for your specific issue, can you attach the model you are using? The zip I sent above should match what the spec says.
I tried a few models and didn’t see any differences. The sandbox uses left-handed and vscode uses right-handed, but there should be no visible difference.
I believe I’ve figured out the main issue. The rotation quaternion in my gltf was of the form [scalar, …vector], while the extension takes […vector, scalar]. I should have known from the 1 in the default value for rotation that this was the order. It may help if the extension’s documentation is updated to explicitly state the intended quaternion order. Anyways, thanks for looking into the issue and providing your example environment, it was quite helpful.