Move GetTextureDataAsync from inspector to core

[kircher1]

This is a refactor that will eventually enable a serializer like GLTFExporter to use the now core-based GetTextureDataAsync in order to serialize textures that are not directly retrievable as RGBA e.g., GPU-compressed formats.

For more discussion on that point, see #12257. The part that is missing to ultimately solve this is some sort of function or BaseTexture-property that can tell whether the texture uses a GPU compressed format. Once that exists, then it should be easy to do something like this... from glTFMaterialExporter.ts:

[bjsplat]

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[bjsplat]

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[Popov72]

This code copies an existing texture (compressed or not) to a non-compressed RGBA texture, which is not what we want in the exporter (the exporter is already able to export compressed textures, but it exports the result of the expansion to RGBA 8 bits to a .png file, not the original compressed data).

[EDIT]
My bad, I really thought the exporter was able to export a compressed texture, though in non-compressed format!
But I tested it in a simple PG and it didn't work...
So, I guess there's a need for the PR after all.
[/EDIT]

To be able to export compressed textures in their compressed form, we would need to be able to retrieve the compressed data, which is not possible because readPixels does not work in this case:

https://playground.babylonjs.com/#E6WY1N

You will get this error in the console log:

[.WebGL-00002DB408078E00] GL_INVALID_FRAMEBUFFER_OPERATION: Framebuffer is incomplete: Attachment is not renderable.

And the buffer will be all zero.

Even if that worked, you would only get the transcoded data that was suitable for the target GPU when the texture has been created, whereas you would need the non-transcoded data for the export.

Regarding the function itself, I'm not sure we should move it into the misc tools, as it seems quite specific to the inspector...

cc @sebavan for his opinion.

[RaananW]

which is not what we want in the exporter

If the decision is whether or not the texture is exported, this seems to be a viable solution

My EDIT - just saw YOUR edit :-). This can be ignored.

[RaananW]

LGTM. I agree with @Popov72 regarding the inspector-only code, which should stay in the inspector

[kircher1]

Yeah, just to clarify, as you found the glTF exporter does not handle GPU compressed textures now. There is a related issue here: #12257

So the idea with this helper function would be to render out a copy of the compressed texture as RGBA. (I have tried a local version of this and it does indeed work. The 'compressed' texture gets serialized as a png)

[sebavan]

@bghgary and @Popov72 can I let you do a last review ?

[bghgary]

I think this is ready to merge.