Add egui_wgpu crate (#1564)

Based on https://github.com/hasenbanck/egui_wgpu_backend

`egui-wgpu` is now an official backend for `eframe` (opt-in).

Use the `wgpu` feature flag on `eframe` and the `NativeOptions::renderer` settings to pick it.

Co-authored-by: Nils Hasenbanck <nils@hasenbanck.de>
Co-authored-by: Sven Niederberger <niederberger@embotech.com>
Co-authored-by: Sven Niederberger <73159570+s-nie@users.noreply.github.com>

egui_demo_app/src/apps/custom3d.rs

@@ -1,5 +1,6 @@
 use std::sync::Arc;
 
+use eframe::egui_glow;
 use egui::mutex::Mutex;
 use egui_glow::glow;
 
@@ -39,8 +40,10 @@ impl eframe::App for Custom3d {
         });
     }
 
-    fn on_exit(&mut self, gl: &glow::Context) {
-        self.rotating_triangle.lock().destroy(gl);
+    fn on_exit(&mut self, gl: Option<&glow::Context>) {
+        if let Some(gl) = gl {
+            self.rotating_triangle.lock().destroy(gl);
+        }
     }
 }
 

egui_demo_app/src/apps/mod.rs

@@ -1,9 +1,15 @@
+#[cfg(feature = "glow")]
 mod custom3d;
+
 mod fractal_clock;
+
 #[cfg(feature = "http")]
 mod http_app;
 
+#[cfg(feature = "glow")]
 pub use custom3d::Custom3d;
+
 pub use fractal_clock::FractalClock;
+
 #[cfg(feature = "http")]
 pub use http_app::HttpApp;

egui_demo_app/src/main.rs

@@ -9,6 +9,10 @@ fn main() {
 
     let options = eframe::NativeOptions {
         drag_and_drop_support: true,
+
+        #[cfg(feature = "wgpu")]
+        renderer: eframe::Renderer::Wgpu,
+
         ..Default::default()
     };
     eframe::run_native(

egui_demo_app/src/wrap_app.rs

@@ -1,5 +1,7 @@
 use egui_demo_lib::is_mobile;
-use egui_glow::glow;
+
+#[cfg(feature = "glow")]
+use eframe::glow;
 
 #[derive(Default)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
@@ -91,7 +93,8 @@ pub struct State {
 pub struct WrapApp {
     state: State,
     // not serialized (because it contains OpenGL buffers etc)
-    custom3d: crate::apps::Custom3d,
+    #[cfg(feature = "glow")]
+    custom3d: Option<crate::apps::Custom3d>,
     dropped_files: Vec<egui::DroppedFile>,
 }
 
@@ -100,7 +103,8 @@ impl WrapApp {
         #[allow(unused_mut)]
         let mut slf = Self {
             state: State::default(),
-            custom3d: crate::apps::Custom3d::new(&cc.gl),
+            #[cfg(feature = "glow")]
+            custom3d: cc.gl.as_ref().map(|gl| crate::apps::Custom3d::new(gl)),
             dropped_files: Default::default(),
         };
 
@@ -121,7 +125,7 @@ impl WrapApp {
     }
 
     fn apps_iter_mut(&mut self) -> impl Iterator<Item = (&str, &str, &mut dyn eframe::App)> {
-        vec![
+        let mut vec = vec![
             (
                 "✨ Demos",
                 "demo",
@@ -143,18 +147,24 @@ impl WrapApp {
                 "clock",
                 &mut self.state.clock as &mut dyn eframe::App,
             ),
-            (
+        ];
+
+        #[cfg(feature = "glow")]
+        if let Some(custom3d) = &mut self.custom3d {
+            vec.push((
                 "🔺 3D painting",
                 "custom3e",
-                &mut self.custom3d as &mut dyn eframe::App,
-            ),
-            (
-                "🎨 Color test",
-                "colors",
-                &mut self.state.color_test as &mut dyn eframe::App,
-            ),
-        ]
-        .into_iter()
+                custom3d as &mut dyn eframe::App,
+            ));
+        }
+
+        vec.push((
+            "🎨 Color test",
+            "colors",
+            &mut self.state.color_test as &mut dyn eframe::App,
+        ));
+
+        vec.into_iter()
     }
 }
 
@@ -212,8 +222,11 @@ impl eframe::App for WrapApp {
         self.ui_file_drag_and_drop(ctx);
     }
 
-    fn on_exit(&mut self, gl: &glow::Context) {
-        self.custom3d.on_exit(gl);
+    #[cfg(feature = "glow")]
+    fn on_exit(&mut self, gl: Option<&glow::Context>) {
+        if let Some(custom3d) = &mut self.custom3d {
+            custom3d.on_exit(gl);
+        }
     }
 }