[wgpu] Expose wgpu::Adapter via RenderState (#2954)

* [wgpu] Expose adapter, better errors, better docs, more code sharing, use stencil bits

* doc fix

* remove unnecessary unsafe

* handle missing framebuffer format

* better handling of renderstate creation in winit.rs

* remove unnecessary use directive

Cargo.lock

@@ -1251,6 +1251,7 @@ dependencies = [
  "epaint",
  "log",
  "puffin",
+ "thiserror",
  "type-map",
  "wgpu",
  "winit",

Cargo.toml

@@ -33,3 +33,6 @@ opt-level = 2 # fast and small wasm, basically same as `opt-level = 's'`
 # Optimize all dependencies even in debug builds (does not affect workspace packages):
 [profile.dev.package."*"]
 opt-level = 2
+
+[workspace.dependencies]
+thiserror = "1.0.37"

crates/eframe/Cargo.toml

@@ -80,7 +80,7 @@ egui = { version = "0.21.0", path = "../egui", default-features = false, feature
   "log",
 ] }
 log = { version = "0.4", features = ["std"] }
-thiserror = "1.0.37"
+thiserror.workspace = true
 
 #! ### Optional dependencies
 ## Enable this when generating docs.

crates/eframe/src/epi/mod.rs

@@ -312,10 +312,6 @@ pub struct NativeOptions {
     /// Sets the number of bits in the depth buffer.
     ///
     /// `egui` doesn't need the depth buffer, so the default value is 0.
-    ///
-    /// On `wgpu` backends, due to limited depth texture format options, this
-    /// will be interpreted as a boolean (non-zero = true) for whether or not
-    /// specifically a `Depth32Float` buffer is used.
     pub depth_buffer: u8,
 
     /// Sets the number of bits in the stencil buffer.
@@ -475,6 +471,12 @@ pub struct WebOptions {
     /// Default: `Theme::Dark`.
     pub default_theme: Theme,
 
+    /// Sets the number of bits in the depth buffer.
+    ///
+    /// `egui` doesn't need the depth buffer, so the default value is 0.
+    /// Unused by webgl context as of writing.
+    pub depth_buffer: u8,
+
     /// Which version of WebGl context to select
     ///
     /// Default: [`WebGlContextOption::BestFirst`].
@@ -492,6 +494,7 @@ impl Default for WebOptions {
         Self {
             follow_system_theme: true,
             default_theme: Theme::Dark,
+            depth_buffer: 0,
 
             #[cfg(feature = "glow")]
             webgl_context_option: WebGlContextOption::BestFirst,

crates/eframe/src/native/run.rs

@@ -1122,9 +1122,7 @@ mod wgpu_integration {
         ) -> std::result::Result<(), egui_wgpu::WgpuError> {
             self.window = Some(window);
             if let Some(running) = &mut self.running {
-                unsafe {
-                    pollster::block_on(running.painter.set_window(self.window.as_ref()))?;
-                }
+                pollster::block_on(running.painter.set_window(self.window.as_ref()))?;
             }
             Ok(())
         }
@@ -1134,9 +1132,7 @@ mod wgpu_integration {
         fn drop_window(&mut self) -> std::result::Result<(), egui_wgpu::WgpuError> {
             self.window = None;
             if let Some(running) = &mut self.running {
-                unsafe {
-                    pollster::block_on(running.painter.set_window(None))?;
-                }
+                pollster::block_on(running.painter.set_window(None))?;
             }
             Ok(())
         }
@@ -1148,16 +1144,16 @@ mod wgpu_integration {
             window: winit::window::Window,
         ) -> std::result::Result<(), egui_wgpu::WgpuError> {
             #[allow(unsafe_code, unused_mut, unused_unsafe)]
-            let painter = unsafe {
-                let mut painter = egui_wgpu::winit::Painter::new(
-                    self.native_options.wgpu_options.clone(),
-                    self.native_options.multisampling.max(1) as _,
+            let mut painter = egui_wgpu::winit::Painter::new(
+                self.native_options.wgpu_options.clone(),
+                self.native_options.multisampling.max(1) as _,
+                egui_wgpu::depth_format_from_bits(
                     self.native_options.depth_buffer,
-                    self.native_options.transparent,
-                );
-                pollster::block_on(painter.set_window(Some(&window)))?;
-                painter
-            };
+                    self.native_options.stencil_buffer,
+                ),
+                self.native_options.transparent,
+            );
+            pollster::block_on(painter.set_window(Some(&window)))?;
 
             let wgpu_render_state = painter.render_state();
 

crates/eframe/src/web/web_painter_wgpu.rs

@@ -3,7 +3,6 @@ use std::sync::Arc;
 use wasm_bindgen::JsValue;
 use web_sys::HtmlCanvasElement;
 
-use egui::mutex::RwLock;
 use egui_wgpu::{renderer::ScreenDescriptor, RenderState, SurfaceErrorAction};
 
 use crate::WebOptions;
@@ -99,43 +98,20 @@ impl WebPainterWgpu {
         }
         .map_err(|err| format!("failed to create wgpu surface: {err}"))?;
 
-        let adapter = instance
-            .request_adapter(&wgpu::RequestAdapterOptions {
-                power_preference: options.wgpu_options.power_preference,
-                force_fallback_adapter: false,
-                compatible_surface: None,
-            })
-            .await
-            .ok_or_else(|| "No suitable GPU adapters found on the system".to_owned())?;
-
-        let (device, queue) = adapter
-            .request_device(
-                &(*options.wgpu_options.device_descriptor)(&adapter),
-                None, // Capture doesn't work in the browser environment.
-            )
-            .await
-            .map_err(|err| format!("Failed to find wgpu device: {}", err))?;
-
-        let target_format =
-            egui_wgpu::preferred_framebuffer_format(&surface.get_capabilities(&adapter).formats);
-
-        let depth_format = options.wgpu_options.depth_format;
-        let renderer = egui_wgpu::Renderer::new(&device, target_format, depth_format, 1);
-        let render_state = RenderState {
-            device: Arc::new(device),
-            queue: Arc::new(queue),
-            target_format,
-            renderer: Arc::new(RwLock::new(renderer)),
-        };
+        let depth_format = egui_wgpu::depth_format_from_bits(options.depth_buffer, 0);
+        let render_state =
+            RenderState::create(&options.wgpu_options, &instance, &surface, depth_format, 1)
+                .await
+                .map_err(|err| err.to_string())?;
 
         let surface_configuration = wgpu::SurfaceConfiguration {
             usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
-            format: target_format,
+            format: render_state.target_format,
             width: 0,
             height: 0,
             present_mode: options.wgpu_options.present_mode,
             alpha_mode: wgpu::CompositeAlphaMode::Auto,
-            view_formats: vec![target_format],
+            view_formats: vec![render_state.target_format],
         };
 
         log::debug!("wgpu painter initialized.");

crates/egui-wgpu/Cargo.toml

@@ -42,6 +42,7 @@ epaint = { version = "0.21.0", path = "../epaint", default-features = false, fea
 
 bytemuck = "1.7"
 log = { version = "0.4", features = ["std"] }
+thiserror.workspace = true
 type-map = "0.5.0"
 wgpu = "0.16.0"
 

crates/egui-wgpu/src/lib.rs

@@ -21,15 +21,80 @@ use std::sync::Arc;
 
 use epaint::mutex::RwLock;
 
+#[derive(thiserror::Error, Debug)]
+pub enum WgpuError {
+    #[error("Failed to create wgpu adapter, no suitable adapter found.")]
+    NoSuitableAdapterFound,
+
+    #[error("There was no valid format for the surface at all.")]
+    NoSurfaceFormatsAvailable,
+
+    #[error(transparent)]
+    RequestDeviceError(#[from] wgpu::RequestDeviceError),
+
+    #[error(transparent)]
+    CreateSurfaceError(#[from] wgpu::CreateSurfaceError),
+}
+
 /// Access to the render state for egui.
 #[derive(Clone)]
 pub struct RenderState {
+    /// Wgpu adapter used for rendering.
+    pub adapter: Arc<wgpu::Adapter>,
+
+    /// Wgpu device used for rendering, created from the adapter.
     pub device: Arc<wgpu::Device>,
+
+    /// Wgpu queue used for rendering, created from the adapter.
     pub queue: Arc<wgpu::Queue>,
+
+    /// The target texture format used for presenting to the window.
     pub target_format: wgpu::TextureFormat,
+
+    /// Egui renderer responsible for drawing the UI.
     pub renderer: Arc<RwLock<Renderer>>,
 }
 
+impl RenderState {
+    /// Creates a new `RenderState`, containing everything needed for drawing egui with wgpu.
+    ///
+    /// # Errors
+    /// Wgpu initialization may fail due to incompatible hardware or driver for a given config.
+    pub async fn create(
+        config: &WgpuConfiguration,
+        instance: &wgpu::Instance,
+        surface: &wgpu::Surface,
+        depth_format: Option<wgpu::TextureFormat>,
+        msaa_samples: u32,
+    ) -> Result<Self, WgpuError> {
+        let adapter = instance
+            .request_adapter(&wgpu::RequestAdapterOptions {
+                power_preference: config.power_preference,
+                compatible_surface: Some(surface),
+                force_fallback_adapter: false,
+            })
+            .await
+            .ok_or(WgpuError::NoSuitableAdapterFound)?;
+
+        let target_format =
+            crate::preferred_framebuffer_format(&surface.get_capabilities(&adapter).formats)?;
+
+        let (device, queue) = adapter
+            .request_device(&(*config.device_descriptor)(&adapter), None)
+            .await?;
+
+        let renderer = Renderer::new(&device, target_format, depth_format, msaa_samples);
+
+        Ok(RenderState {
+            adapter: Arc::new(adapter),
+            device: Arc::new(device),
+            queue: Arc::new(queue),
+            target_format,
+            renderer: Arc::new(RwLock::new(renderer)),
+        })
+    }
+}
+
 /// Specifies which action should be taken as consequence of a [`wgpu::SurfaceError`]
 pub enum SurfaceErrorAction {
     /// Do nothing and skip the current frame.
@@ -56,8 +121,6 @@ pub struct WgpuConfiguration {
 
     /// Callback for surface errors.
     pub on_surface_error: Arc<dyn Fn(wgpu::SurfaceError) -> SurfaceErrorAction>,
-
-    pub depth_format: Option<wgpu::TextureFormat>,
 }
 
 impl Default for WgpuConfiguration {
@@ -88,7 +151,6 @@ impl Default for WgpuConfiguration {
             present_mode: wgpu::PresentMode::AutoVsync,
             power_preference: wgpu::util::power_preference_from_env()
                 .unwrap_or(wgpu::PowerPreference::HighPerformance),
-            depth_format: None,
 
             on_surface_error: Arc::new(|err| {
                 if err == wgpu::SurfaceError::Outdated {
@@ -105,50 +167,40 @@ impl Default for WgpuConfiguration {
 }
 
 /// Find the framebuffer format that egui prefers
-pub fn preferred_framebuffer_format(formats: &[wgpu::TextureFormat]) -> wgpu::TextureFormat {
+///
+/// # Errors
+/// Returns [`WgpuError::NoSurfaceFormatsAvailable`] if the given list of formats is empty.
+pub fn preferred_framebuffer_format(
+    formats: &[wgpu::TextureFormat],
+) -> Result<wgpu::TextureFormat, WgpuError> {
     for &format in formats {
         if matches!(
             format,
             wgpu::TextureFormat::Rgba8Unorm | wgpu::TextureFormat::Bgra8Unorm
         ) {
-            return format;
+            return Ok(format);
         }
     }
-    formats[0] // take the first
-}
-// maybe use this-error?
-#[derive(Debug)]
-pub enum WgpuError {
-    DeviceError(wgpu::RequestDeviceError),
-    SurfaceError(wgpu::CreateSurfaceError),
-}
-
-impl std::fmt::Display for WgpuError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        std::fmt::Debug::fmt(self, f)
-    }
-}
 
-impl std::error::Error for WgpuError {
-    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
-        match self {
-            WgpuError::DeviceError(e) => e.source(),
-            WgpuError::SurfaceError(e) => e.source(),
-        }
-    }
+    formats
+        .get(0)
+        .copied()
+        .ok_or(WgpuError::NoSurfaceFormatsAvailable)
 }
 
-impl From<wgpu::RequestDeviceError> for WgpuError {
-    fn from(e: wgpu::RequestDeviceError) -> Self {
-        Self::DeviceError(e)
+/// Take's epi's depth/stencil bits and returns the corresponding wgpu format.
+pub fn depth_format_from_bits(depth_buffer: u8, stencil_buffer: u8) -> Option<wgpu::TextureFormat> {
+    match (depth_buffer, stencil_buffer) {
+        (0, 8) => Some(wgpu::TextureFormat::Stencil8),
+        (16, 0) => Some(wgpu::TextureFormat::Depth16Unorm),
+        (24, 0) => Some(wgpu::TextureFormat::Depth24Plus),
+        (24, 8) => Some(wgpu::TextureFormat::Depth24PlusStencil8),
+        (32, 0) => Some(wgpu::TextureFormat::Depth32Float),
+        (32, 8) => Some(wgpu::TextureFormat::Depth32FloatStencil8),
+        _ => None,
     }
 }
 
-impl From<wgpu::CreateSurfaceError> for WgpuError {
-    fn from(e: wgpu::CreateSurfaceError) -> Self {
-        Self::SurfaceError(e)
-    }
-}
 // ---------------------------------------------------------------------------
 
 /// Profiling macro for feature "puffin"

crates/egui-wgpu/src/winit.rs

@@ -1,8 +1,6 @@
 use std::sync::Arc;
 
-use epaint::{self, mutex::RwLock};
-
-use crate::{renderer, RenderState, Renderer, SurfaceErrorAction, WgpuConfiguration};
+use crate::{renderer, RenderState, SurfaceErrorAction, WgpuConfiguration};
 
 struct SurfaceState {
     surface: wgpu::Surface,
@@ -83,7 +81,6 @@ pub struct Painter {
     screen_capture_state: Option<CaptureState>,
 
     instance: wgpu::Instance,
-    adapter: Option<wgpu::Adapter>,
     render_state: Option<RenderState>,
     surface_state: Option<SurfaceState>,
 }
@@ -104,7 +101,7 @@ impl Painter {
     pub fn new(
         configuration: WgpuConfiguration,
         msaa_samples: u32,
-        depth_bits: u8,
+        depth_format: Option<wgpu::TextureFormat>,
         support_transparent_backbuffer: bool,
     ) -> Self {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
@@ -116,12 +113,11 @@ impl Painter {
             configuration,
             msaa_samples,
             support_transparent_backbuffer,
-            depth_format: (depth_bits > 0).then_some(wgpu::TextureFormat::Depth32Float),
+            depth_format,
             depth_texture_view: None,
             screen_capture_state: None,
 
             instance,
-            adapter: None,
             render_state: None,
             surface_state: None,
             msaa_texture_view: None,
@@ -135,60 +131,6 @@ impl Painter {
         self.render_state.clone()
     }
 
-    async fn init_render_state(
-        &self,
-        adapter: &wgpu::Adapter,
-        target_format: wgpu::TextureFormat,
-    ) -> Result<RenderState, wgpu::RequestDeviceError> {
-        adapter
-            .request_device(&(*self.configuration.device_descriptor)(adapter), None)
-            .await
-            .map(|(device, queue)| {
-                let renderer =
-                    Renderer::new(&device, target_format, self.depth_format, self.msaa_samples);
-                RenderState {
-                    device: Arc::new(device),
-                    queue: Arc::new(queue),
-                    target_format,
-                    renderer: Arc::new(RwLock::new(renderer)),
-                }
-            })
-    }
-
-    // We want to defer the initialization of our render state until we have a surface
-    // so we can take its format into account.
-    //
-    // After we've initialized our render state once though we expect all future surfaces
-    // will have the same format and so this render state will remain valid.
-    async fn ensure_render_state_for_surface(
-        &mut self,
-        surface: &wgpu::Surface,
-    ) -> Result<(), wgpu::RequestDeviceError> {
-        if self.adapter.is_none() {
-            self.adapter = self
-                .instance
-                .request_adapter(&wgpu::RequestAdapterOptions {
-                    power_preference: self.configuration.power_preference,
-                    compatible_surface: Some(surface),
-                    force_fallback_adapter: false,
-                })
-                .await;
-        }
-        if self.render_state.is_none() {
-            match &self.adapter {
-                Some(adapter) => {
-                    let swapchain_format = crate::preferred_framebuffer_format(
-                        &surface.get_capabilities(adapter).formats,
-                    );
-                    let rs = self.init_render_state(adapter, swapchain_format).await?;
-                    self.render_state = Some(rs);
-                }
-                None => return Err(wgpu::RequestDeviceError {}),
-            }
-        }
-        Ok(())
-    }
-
     fn configure_surface(
         surface_state: &SurfaceState,
         render_state: &RenderState,
@@ -235,20 +177,31 @@ impl Painter {
     ///
     /// # Errors
     /// If the provided wgpu configuration does not match an available device.
-    pub async unsafe fn set_window(
+    pub async fn set_window(
         &mut self,
         window: Option<&winit::window::Window>,
     ) -> Result<(), crate::WgpuError> {
         match window {
             Some(window) => {
-                let surface = self.instance.create_surface(&window)?;
+                let surface = unsafe { self.instance.create_surface(&window)? };
 
-                self.ensure_render_state_for_surface(&surface).await?;
+                let render_state = if let Some(render_state) = &self.render_state {
+                    render_state
+                } else {
+                    let render_state = RenderState::create(
+                        &self.configuration,
+                        &self.instance,
+                        &surface,
+                        self.depth_format,
+                        self.msaa_samples,
+                    )
+                    .await?;
+                    self.render_state.get_or_insert(render_state)
+                };
 
                 let alpha_mode = if self.support_transparent_backbuffer {
-                    let supported_alpha_modes = surface
-                        .get_capabilities(self.adapter.as_ref().unwrap())
-                        .alpha_modes;
+                    let supported_alpha_modes =
+                        surface.get_capabilities(&render_state.adapter).alpha_modes;
 
                     // Prefer pre multiplied over post multiplied!
                     if supported_alpha_modes.contains(&wgpu::CompositeAlphaMode::PreMultiplied) {