Update to work with bevy main (and eventually 0.8)

[DGriffin91]

This needs a more thorough review. But it looks like the examples are working, and it's working in at least one of my projects.

[zimond]

This is broken as bevy#4402 landed

[DGriffin91]

Just messed with it a bit and it seems like this will require a bit of a more significant re-work now as the extract systems currently require mutable access to resources in the main world.

[zimond]

Yes and using immutable Res with clone could make the examples run, but with only a black screen code I didn't have the time to dig in

[DGriffin91]

@zimond I tried using the clone with egui_render_output in the extract instead of take and it looks like it's working for me (at least with the included examples). I would assume the clone here is less efficient than take, but I'm not sure if it's enough slower to matter.

[zimond]

I think some clones won't hurt the perf that much

[mvlabat]

Hi! Thank you for the PR! I think cloning is fine for now. Maybe, if we see an issue with performance, we might want to wrap it into a Mutex, if copying a lot of bytes around will become more expensive than dealing with locking.
I've also pushed a small commit to refactor the example, to make the error of initialization more visible (it'll panic now if we forget to initialize the camera properly, instead of making it silent) and fix the linters.

[zimond]

Closing a window on this branch emits panic:

let extracted_window = &world.get_resource::<ExtractedWindows>().unwrap().windows[&self.window_id];

thread 'main' panicked at 'no entry found for key' egui_node.rs:328:14

[DGriffin91]

Hmm, I tried this

        let extracted_windows = &world.get_resource::<ExtractedWindows>().unwrap().windows;

        let extracted_window =
            if let Some(extracted_window) = extracted_windows.get(&self.window_id) {
                extracted_window
            } else {
                return Ok(());
            };

But now when I close the window the app continues to run with the window closed and says:

2022-07-18T16:59:55.466789Z  INFO bevy_winit: Skipped event for closed window: WindowId(00000000-0000-0000-0000-000000000000)
2022-07-18T16:59:55.467187Z  INFO bevy_winit: Skipped event for closed window: WindowId(00000000-0000-0000-0000-000000000000)
2022-07-18T16:59:55.470299Z  INFO bevy_winit: Skipped event for closed window: WindowId(00000000-0000-0000-0000-000000000000)

[mvlabat]

Any chance that this is an issue on the Bevy's end? Not really sure what can cause this in bevy_egui itself.
I haven't got a chance to look into it myself, but does it happen with every example? Or is it specific to the multiple windows example?

If it happens in every example, I'd suggest to try to reproduce it in a clean Bevy project. And if it reproduces there without bevy_egui, we need to file an issue in their repo.

[DGriffin91]

@mvlabat It appears that it is indeed an issue with bevy: bevyengine/bevy#5384

[CGMossa]

Is this issue blocking this PR or has it been fixed?

[mvlabat]

Definitely not a blocker for us. I don't know if it has been fixed in Bevy's main, but we'll merge this PR regardless once 0.8 is released

[philpax]

Bevy 0.8's now out - I've just built this fork with it (opened a PR for it here DGriffin91#2) and everything seems to work fine 👍

[mvlabat]

Thank you for your help with the update! I'll release it soon