Re-implement PaintCallbacks With Support for WGPU

CHANGELOG.md

@@ -12,6 +12,10 @@ NOTE: [`epaint`](epaint/CHANGELOG.md), [`eframe`](eframe/CHANGELOG.md), [`egui-w
 * Added opt-in feature `deadlock_detection` to detect double-lock of mutexes on the same thread ([#1619](https://github.com/emilk/egui/pull/1619)).
 * Added `InputState::stable_dt`: a more stable estimate for the delta-time in reactive mode ([#1625](https://github.com/emilk/egui/pull/1625)).
 * You can now specify a texture filter for your textures ([#1636](https://github.com/emilk/egui/pull/1636)).
+* Added support for using `PaintCallback` shapes with the WGPU backend ([#1684](https://github.com/emilk/egui/pull/1684))
+
+### Changed
+* `PaintCallback` shapes now require the whole callback to be put in an `Arc<dyn Any>` with the value being a backend-specific callback type. ([#1684](https://github.com/emilk/egui/pull/1684))
 
 ### Fixed 🐛
 * Fixed `ImageButton`'s changing background padding on hover ([#1595](https://github.com/emilk/egui/pull/1595)).

eframe/src/epi.rs

@@ -29,6 +29,11 @@ pub struct CreationContext<'s> {
     /// you might want to use later from a [`egui::PaintCallback`].
     #[cfg(feature = "glow")]
     pub gl: Option<std::sync::Arc<glow::Context>>,
+
+    /// Can be used to manage GPU resources for custom rendering with WGPU using
+    /// [`egui::PaintCallback`]s.
+    #[cfg(feature = "wgpu")]
+    pub render_state: Option<egui_wgpu::RenderState>,
 }
 
 // ----------------------------------------------------------------------------
@@ -335,6 +340,11 @@ pub struct Frame {
     #[cfg(feature = "glow")]
     #[doc(hidden)]
     pub gl: Option<std::sync::Arc<glow::Context>>,
+
+    /// Can be used to manage GPU resources for custom rendering with WGPU using
+    /// [`egui::PaintCallback`]s.
+    #[cfg(feature = "wgpu")]
+    pub render_state: Option<egui_wgpu::RenderState>,
 }
 
 impl Frame {

eframe/src/lib.rs

@@ -61,6 +61,9 @@ pub use {egui, egui::emath, egui::epaint};
 #[cfg(feature = "glow")]
 pub use {egui_glow, glow};
 
+#[cfg(feature = "wgpu")]
+pub use {egui_wgpu, wgpu};
+
 mod epi;
 
 // Re-export everything in `epi` so `eframe` users don't have to care about what `epi` is:

eframe/src/native/epi_integration.rs

@@ -188,6 +188,7 @@ impl EpiIntegration {
         window: &winit::window::Window,
         storage: Option<Box<dyn epi::Storage>>,
         #[cfg(feature = "glow")] gl: Option<std::sync::Arc<glow::Context>>,
+        #[cfg(feature = "wgpu")] render_state: Option<egui_wgpu::RenderState>,
     ) -> Self {
         let egui_ctx = egui::Context::default();
 
@@ -207,6 +208,8 @@ impl EpiIntegration {
             storage,
             #[cfg(feature = "glow")]
             gl,
+            #[cfg(feature = "wgpu")]
+            render_state,
         };
 
         if prefer_dark_mode == Some(true) {

eframe/src/native/run.rs

@@ -62,6 +62,8 @@ pub fn run_glow(
         gl_window.window(),
         storage,
         Some(gl.clone()),
+        #[cfg(feature = "wgpu")]
+        None,
     );
 
     {
@@ -76,6 +78,8 @@ pub fn run_glow(
         integration_info: integration.frame.info(),
         storage: integration.frame.storage(),
         gl: Some(gl.clone()),
+        #[cfg(feature = "wgpu")]
+        render_state: None,
     });
 
     if app.warm_up_enabled() {
@@ -230,13 +234,16 @@ pub fn run_wgpu(
         painter
     };
 
+    let render_state = painter.get_render_state().expect("Uninitialized");
+
     let mut integration = epi_integration::EpiIntegration::new(
         &event_loop,
         painter.max_texture_side().unwrap_or(2048),
         &window,
         storage,
         #[cfg(feature = "glow")]
         None,
+        Some(render_state.clone()),
     );
 
     {
@@ -252,6 +259,7 @@ pub fn run_wgpu(
         storage: integration.frame.storage(),
         #[cfg(feature = "glow")]
         gl: None,
+        render_state: Some(render_state),
     });
 
     if app.warm_up_enabled() {

eframe/src/web/backend.rs

@@ -170,6 +170,8 @@ impl AppRunner {
             storage: Some(&storage),
             #[cfg(feature = "glow")]
             gl: Some(painter.painter.gl().clone()),
+            #[cfg(feature = "wgpu")]
+            render_state: None,
         });
 
         let frame = epi::Frame {
@@ -178,6 +180,8 @@ impl AppRunner {
             storage: Some(Box::new(storage)),
             #[cfg(feature = "glow")]
             gl: Some(painter.gl().clone()),
+            #[cfg(feature = "wgpu")]
+            render_state: None,
         };
 
         let needs_repaint: std::sync::Arc<NeedRepaint> = Default::default();

egui-wgpu/Cargo.toml

@@ -37,6 +37,7 @@ egui = { version = "0.18.1", path = "../egui", default-features = false, feature
 
 bytemuck = "1.7"
 tracing = "0.1"
+type-map = "0.5.0"
 wgpu = { version = "0.12", features = ["webgl"] }
 
 # Optional:

egui-wgpu/src/lib.rs

@@ -6,7 +6,10 @@ pub use wgpu;
 
 /// Low-level painting of [`egui`] on [`wgpu`].
 pub mod renderer;
+pub use renderer::CallbackFn;
 
 /// Module for painting [`egui`] with [`wgpu`] on [`winit`].
 #[cfg(feature = "winit")]
 pub mod winit;
+#[cfg(feature = "winit")]
+pub use crate::winit::RenderState;