Allow skipping pixel-format OpenGL profile attributes

[davidhozic]

• Tested on all platforms changed
• Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality

This is essentially the same as #1740 , with the exception of allowing configurable behavior and in being more compact. By default, nothing is changed to the previous behavior of glutin on macOS (CGL) except the added no-profile fallback when all prior profile selections fail.

Essentially, it addresses the problem of certain OpenGL extensions not working on macOS (ARB_framebuffer_object).

All the formatting errors are pre-existing.

[davidhozic]

@kchibisov This makes minimal changes to the behavor and preserves the original behavior of when nothing is specified.

Maybe just a thought for the future. From what I can tell, there is no reason for the profile selection not being inside the Display::create_context method; before the context creation:

glutin/glutin/src/api/cgl/context.rs

Line 53 in e2f87ad

let raw = NSOpenGLContext::initWithFormat_shareContext(

Is there a reason that it is currently inside the find_configs method? On other platforms, the profile selection is set via ContextAttributesBuilder::with_context_api and ContextAttributesBuilder::with_profile.

[davidhozic]

I tested it and it now works on macOS, in addition to the existing unchanged platforms.

[kchibisov]

I think there was some macOS specific reason for that, but I can not recall it. Moving it and align with other platforms would have been better, in my opinion.

Maybe something related to send/sync or some OpenGL quirks macOS have given that apple considers it legacy. Would suggest to just browse git history, could be a reason for, since I think it was like that with even original glutin design.

[davidhozic]

I think there was some macOS specific reason for that, but I can not recall it. Moving it and align with other platforms would have been better, in my opinion.

Maybe something related to send/sync or some OpenGL quirks macOS have given that apple considers it legacy. Would suggest to just browse git history, could be a reason for, since I think it was like that with even original glutin design.

From what I can tell it should work. The exception will be that errors will not be caught in find_configs. Perhaps it is best to leave this configuration inside find_configs for now and change it sometime in the future if it turns problematic.

[kchibisov]

Can we infer it from with_api/Api instead?

[davidhozic]

By skipping profile selection when ConfigTemplate::api is None? We can do that if you're okay with profile selection being skipped by default.

[kchibisov]

I think so, though, it's technically a behavior change, but probably it's fine? What it picks on recent enough macs?

[davidhozic]

It will switch to the legacy OpenGL (OpenGL 2.1) + extensions. I'm fine with making it check the ConfigTemplate::api, however it doesn't feel very intuitive that you need to select OpenGL explicitly in the Api Actually it is fine; users will just have to assume they can't rely on OpenGL being selected without with_api on macOS, and it will look to them like something else may be selected.