Bevy: OpenGL support

[jamadazi]

Wgpu now has a working OpenGL backend. I know bevy intends to support that, but it does not work yet.

Creating this issue to make it easier to track progress on that front.

[cart]

Yup just for some additional context, I upgraded bevy to use "git wgpu" here: https://github.com/cart/bevy/tree/upgrade-wgpu, but I get this error:

Probably somehow related to the fact that Bevy does some rendering stuff (like creating gpu resources) on other threads.

[cart]

Using schedule.run() (single threaded) instead of the parallel executor got me past the threading errors.

Then I hit an issue where wgpu didnt like that we use ceil() in sprite_sheet.vert:

Removing that unlocked a new error:

Which indicates that we're using an unsupported binding type:

@kvark I'm just pulling you in so you're aware of where we're at. I'm not asking you for anything :smile:

[cart]

I pushed a new branch with the changes listed above: https://github.com/cart/bevy/tree/opengl-testing

[kvark]

It's too early for Bevy to play with our OpenGL backend. Let us at least get our own samples running first :sweat_smile: