texSubImage2D optimisation for cube maps

[Rik Cabanier]

All,

I'm seeing some strange behavior where 6 calls to `texSubImage2D` with an image for each cubemap side are coalesced into a single `texSubImage2D` call.

Does anyone know where in the chromium stack this is happening?

This code is not executing correctly in our product and I'm trying to investigate why.

[Zhenyao Mo]

AFAIK: there is no GL API to upload images to all six cubemap sides in
one GL call. So I don't think such optimization exists in Chrome.

Why do you think this is what happens in Chrome?

[Rik Cabanier]

I put a debug statement in GLES2Implementation::TexSubImage2D and it is called only once with a texture that includes all sides.

Here is the JS code that makes 6 calls: https://github.com/immersive-web/webxr-samples/blob/main/layers-samples/cube-layer.html#L190

[Rik Cabanier]

Never mind! I was looking at the wrong code :-)