Bevy 0.10

[mvlabat]

Based on #148

[TimJentzsch]

Ci seems to complain about a mutable reference in pipelines.specialize:
https://github.com/mvlabat/bevy_egui/pull/159/files#diff-ab44fb5ff047491ab87031ab0d263274a3deb0951822df16d759522ac9b44fa8L256

[mvlabat]

I'm seeing the following warnings in the ui example:

epaint: WARNING: pixels_per_point (dpi scale) have changed between text layout and tessellation. You must recreate your text shapes if pixels_per_point changes.

I'd be grateful if anyone could pick up this issue. I won't have time to return to the PR until the evening.

[DGriffin91]

I've been trying to track down the pixels_per_point thing. Haven't figured it out yet. This is the commit that added the warning:
emilk/egui@39b63f6

In the ui example, it comes from changing the egui_settings.scale_factor in update_ui_scale_factor_system()

We then set egui_input.pixels_per_point in update_window_contexts() which is called from process_input_system()

We get the shapes in process_output_system()

let full_output = ctx.end_frame();
let egui::FullOutput {
    platform_output,
    shapes,
    textures_delta,
    repaint_after,
} = full_output;

egui_render_output.shapes = shapes;

I think it only shows the warning for one frame if scale_factor changes.

[Vrixyz]

can it be simplified like this?

Suggested change

	fn ui_example_system(mut egui_ctx: Query<&mut EguiContext, With<PrimaryWindow>>) {
	egui::Window::new("Hello").show(egui_ctx.single_mut().get_mut(), |ui| {
	fn ui_example_system(egui_ctx: Query<&EguiContext, With<PrimaryWindow>>) {
	egui::Window::new("Hello").show(egui_ctx.single(), |ui| {

[mvlabat]

Only if we implement Deref and DerefMut for EguiContext, giving people an interface to borrow the context immutably, which I'm hesitant to do due to the following:

bevy_egui/src/lib.rs

Lines 247 to 256 in 7151c40

	/// Even though the mutable borrow isn't necessary, as the context is wrapped into `RwLock`,
	/// using the immutable getter is gated with the `immutable_ctx` feature. Using the immutable
	/// borrow is discouraged as it may cause unpredictable blocking in UI systems.
	///
	/// When the context is queried with `&mut EguiContext`, the Bevy scheduler is able to make
	/// sure that the context isn't accessed concurrently and can perform other useful work
	/// instead of busy-waiting.
	pub fn get_mut(&mut self) -> &mut egui::Context {
	&mut self.0
	}

[mvlabat]

I ended up introducing the EguiContexts system param, to combine the best of both worlds: low boilerplate and mutable borrowing by default.

[mvlabat]

@DGriffin91 thanks for looking into this! That definitely saved me time investigating. It seems that I was able to fix the warning here: 7151c40.

[mvlabat]

The PR is almost finished. I'll let people review the API changes, and tomorrow morning I'll push the last bits of the documentation fixes and make a release.