opengl: infer fbo format name in gl_fb_query

[ruihe774]

This PR add format name inference in gl_fb_query() so that end users can easily distinguish formats for e.g. swapchain frames. The format names are consistent with GLSL layout qualifiers.

[haasn]

I'm not sure I understand the use case of this - why do you want access to the GLSL layout qualifier in particular?

Note that pl_fmt_glsl_format exists. Maybe it's better to just call that function instead, and set it to pl_fmt.glsl_format.

[ruihe774]

Note that pl_fmt_glsl_format exists. Maybe it's better to just call that function instead, and set it to pl_fmt.glsl_format.

Reworked. Some formats are not allowed in GLSL, so I add another field.

[kasper93]

The core issue is already fixed by https://code.videolan.org/videolan/libplacebo/-/merge_requests/656 two months ago.

[ruihe774]

The core issue is already fixed by https://code.videolan.org/videolan/libplacebo/-/merge_requests/656 two months ago.

I didn't find that earlier. Sorry.

I've just had a quick look at your implementation and am wondering how it handle formats like rgb10_a2. I suppose it will name it as rgba8 incorrectly. I think the only correct and sound way to implement this is to lookup the names in a list, as what I do in this PR.

[NBruderman]

The core issue is already fixed by https://code.videolan.org/videolan/libplacebo/-/merge_requests/656 two months ago.

I see that in the end, this one wasn't merged

[ruihe774]

Any updates?