Reuse a `RenderPass` as much as possible in `iced_wgpu`

8 files changed, 196 insertions, 170 deletions

diff --git a/examples/integration/src/main.rs b/examples/integration/src/main.rs
index 5af30ab1..a7a90ced 100644
--- a/examples/integration/src/main.rs
+++ b/examples/integration/src/main.rs
@@ -250,6 +250,7 @@ pub fn main() {
                                 &device,
                                 &queue,
                                 &mut encoder,
+                                None,
                                 &view,
                                 primitive,
                                 &viewport,
diff --git a/wgpu/Cargo.toml b/wgpu/Cargo.toml
index b3fbfc00..7a6b75f0 100644
--- a/wgpu/Cargo.toml
+++ b/wgpu/Cargo.toml
@@ -59,8 +59,9 @@ path = "../graphics"
 
 [dependencies.glyphon]
 version = "0.2"
-git = "https://github.com/hecrj/glyphon.git"
-rev = "3c2acb9dea5b9fcb0fa650b3c73b3a3242c62f4a"
+# git = "https://github.com/hecrj/glyphon.git"
+# rev = "3c2acb9dea5b9fcb0fa650b3c73b3a3242c62f4a"
+path = "../../glyphon"
 
 [dependencies.tracing]
 version = "0.1.6"
diff --git a/wgpu/src/backend.rs b/wgpu/src/backend.rs
index 8c4c0daa..9d1e3d1c 100644
--- a/wgpu/src/backend.rs
+++ b/wgpu/src/backend.rs
@@ -5,8 +5,7 @@ use crate::{Settings, Transformation};
 
 use iced_graphics::backend;
 use iced_graphics::layer::Layer;
-use iced_graphics::{Primitive, Viewport};
-use iced_native::{Font, Size};
+use iced_graphics::{Color, Font, Primitive, Size, Viewport};
 
 #[cfg(feature = "tracing")]
 use tracing::info_span;
@@ -71,6 +70,7 @@ impl Backend {
         device: &wgpu::Device,
         queue: &wgpu::Queue,
         encoder: &mut wgpu::CommandEncoder,
+        clear_color: Option<Color>,
         frame: &wgpu::TextureView,
         primitives: &[Primitive],
         viewport: &Viewport,
@@ -87,18 +87,25 @@ impl Backend {
         let mut layers = Layer::generate(primitives, viewport);
         layers.push(Layer::overlay(overlay_text, viewport));
 
-        for layer in layers {
-            self.flush(
-                device,
-                queue,
-                scale_factor,
-                transformation,
-                &layer,
-                encoder,
-                frame,
-                target_size,
-            );
-        }
+        self.prepare(
+            device,
+            queue,
+            encoder,
+            scale_factor,
+            transformation,
+            target_size,
+            &layers,
+        );
+
+        self.render(
+            device,
+            encoder,
+            frame,
+            clear_color,
+            scale_factor,
+            target_size,
+            &layers,
+        );
 
         self.quad_pipeline.end_frame();
         self.text_pipeline.end_frame();
@@ -108,90 +115,153 @@ impl Backend {
         self.image_pipeline.end_frame(device, queue, encoder);
     }
 
-    fn flush(
+    fn prepare(
         &mut self,
         device: &wgpu::Device,
         queue: &wgpu::Queue,
+        _encoder: &mut wgpu::CommandEncoder,
         scale_factor: f32,
         transformation: Transformation,
-        layer: &Layer<'_>,
-        encoder: &mut wgpu::CommandEncoder,
-        target: &wgpu::TextureView,
         target_size: Size<u32>,
+        layers: &[Layer<'_>],
     ) {
-        let bounds = (layer.bounds * scale_factor).snap();
+        for layer in layers {
+            let bounds = (layer.bounds * scale_factor).snap();
 
-        if bounds.width < 1 || bounds.height < 1 {
-            return;
-        }
+            if bounds.width < 1 || bounds.height < 1 {
+                return;
+            }
 
-        if !layer.quads.is_empty() {
-            self.quad_pipeline.prepare(
-                device,
-                queue,
-                &layer.quads,
-                transformation,
-                scale_factor,
-            );
-
-            let mut render_pass =
-                encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
-                    label: Some("iced_wgpu::quad render pass"),
-                    color_attachments: &[Some(
-                        wgpu::RenderPassColorAttachment {
-                            view: target,
-                            resolve_target: None,
-                            ops: wgpu::Operations {
-                                load: wgpu::LoadOp::Load,
-                                store: true,
-                            },
-                        },
-                    )],
-                    depth_stencil_attachment: None,
-                });
+            if !layer.quads.is_empty() {
+                self.quad_pipeline.prepare(
+                    device,
+                    queue,
+                    &layer.quads,
+                    transformation,
+                    scale_factor,
+                );
+            }
 
-            self.quad_pipeline.render(bounds, &mut render_pass);
-        }
+            if !layer.meshes.is_empty() {
+                let scaled = transformation
+                    * Transformation::scale(scale_factor, scale_factor);
+
+                self.triangle_pipeline.prepare(
+                    device,
+                    queue,
+                    &layer.meshes,
+                    scaled,
+                );
+            }
 
-        if !layer.meshes.is_empty() {
-            let scaled = transformation
-                * Transformation::scale(scale_factor, scale_factor);
-
-            self.triangle_pipeline.prepare(
-                device,
-                queue,
-                &layer.meshes,
-                scaled,
-            );
-
-            self.triangle_pipeline.render(
-                device,
-                encoder,
-                target,
-                target_size,
-                &layer.meshes,
-                scale_factor,
-            );
+            #[cfg(any(feature = "image", feature = "svg"))]
+            {
+                if !layer.images.is_empty() {
+                    let scaled = transformation
+                        * Transformation::scale(scale_factor, scale_factor);
+
+                    self.image_pipeline.prepare(
+                        device,
+                        queue,
+                        _encoder,
+                        &layer.images,
+                        scaled,
+                        scale_factor,
+                    );
+                }
+            }
+
+            if !layer.text.is_empty() {
+                self.text_pipeline.prepare(
+                    device,
+                    queue,
+                    &layer.text,
+                    layer.bounds,
+                    scale_factor,
+                    target_size,
+                );
+            }
         }
+    }
 
+    fn render(
+        &mut self,
+        device: &wgpu::Device,
+        encoder: &mut wgpu::CommandEncoder,
+        target: &wgpu::TextureView,
+        clear_color: Option<Color>,
+        scale_factor: f32,
+        target_size: Size<u32>,
+        layers: &[Layer<'_>],
+    ) {
+        use std::mem::ManuallyDrop;
+
+        let mut quad_layer = 0;
+        let mut triangle_layer = 0;
         #[cfg(any(feature = "image", feature = "svg"))]
-        {
-            if !layer.images.is_empty() {
-                let scaled = transformation
-                    * Transformation::scale(scale_factor, scale_factor);
+        let mut image_layer = 0;
+        let mut text_layer = 0;
+
+        let mut render_pass = ManuallyDrop::new(encoder.begin_render_pass(
+            &wgpu::RenderPassDescriptor {
+                label: Some("iced_wgpu::quad render pass"),
+                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                    view: target,
+                    resolve_target: None,
+                    ops: wgpu::Operations {
+                        load: match clear_color {
+                            Some(background_color) => wgpu::LoadOp::Clear({
+                                let [r, g, b, a] =
+                                    background_color.into_linear();
+
+                                wgpu::Color {
+                                    r: f64::from(r),
+                                    g: f64::from(g),
+                                    b: f64::from(b),
+                                    a: f64::from(a),
+                                }
+                            }),
+                            None => wgpu::LoadOp::Load,
+                        },
+                        store: true,
+                    },
+                })],
+                depth_stencil_attachment: None,
+            },
+        ));
+
+        for layer in layers {
+            let bounds = (layer.bounds * scale_factor).snap();
 
-                self.image_pipeline.prepare(
+            if bounds.width < 1 || bounds.height < 1 {
+                return;
+            }
+
+            if !layer.quads.is_empty() {
+                self.quad_pipeline
+                    .render(quad_layer, bounds, &mut render_pass);
+
+                quad_layer += 1;
+            }
+
+            if !layer.meshes.is_empty() {
+                let _ = ManuallyDrop::into_inner(render_pass);
+
+                self.triangle_pipeline.render(
                     device,
-                    queue,
                     encoder,
-                    &layer.images,
-                    scaled,
+                    target,
+                    triangle_layer,
+                    target_size,
+                    &layer.meshes,
                     scale_factor,
                 );
 
-                let mut render_pass =
-                    encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
-                        label: Some("iced_wgpu::image render pass"),
+                triangle_layer += 1;
+
+                render_pass = ManuallyDrop::new(encoder.begin_render_pass(
+                    &wgpu::RenderPassDescriptor {
+                        label: Some("iced_wgpu::quad render pass"),
                         color_attachments: &[Some(
                             wgpu::RenderPassColorAttachment {
                                 view: target,
@@ -203,24 +273,31 @@ impl Backend {
                             },
                         )],
                         depth_stencil_attachment: None,
-                    });
+                    },
+                ));
+            }
 
-                self.image_pipeline.render(bounds, &mut render_pass);
+            #[cfg(any(feature = "image", feature = "svg"))]
+            {
+                if !layer.images.is_empty() {
+                    self.image_pipeline.render(
+                        image_layer,
+                        bounds,
+                        &mut render_pass,
+                    );
+
+                    image_layer += 1;
+                }
             }
-        }
 
-        if !layer.text.is_empty() {
-            self.text_pipeline.prepare(
-                device,
-                queue,
-                &layer.text,
-                layer.bounds,
-                scale_factor,
-                target_size,
-            );
-
-            self.text_pipeline.render(encoder, target);
+            if !layer.text.is_empty() {
+                self.text_pipeline.render(text_layer, &mut render_pass);
+
+                text_layer += 1;
+            }
         }
+
+        let _ = ManuallyDrop::into_inner(render_pass);
     }
 }
 
diff --git a/wgpu/src/image.rs b/wgpu/src/image.rs
index 5d1ae8d7..db05d2ff 100644
--- a/wgpu/src/image.rs
+++ b/wgpu/src/image.rs
@@ -45,7 +45,6 @@ pub struct Pipeline {
 
     layers: Vec<Layer>,
     prepare_layer: usize,
-    render_layer: usize,
 }
 
 #[derive(Debug)]
@@ -321,7 +320,6 @@ impl Pipeline {
 
             layers: Vec::new(),
             prepare_layer: 0,
-            render_layer: 0,
         }
     }
 
@@ -452,11 +450,12 @@ impl Pipeline {
     }
 
     pub fn render<'a>(
-        &'a mut self,
+        &'a self,
+        layer: usize,
         bounds: Rectangle<u32>,
         render_pass: &mut wgpu::RenderPass<'a>,
     ) {
-        if let Some(layer) = self.layers.get(self.render_layer) {
+        if let Some(layer) = self.layers.get(layer) {
             render_pass.set_pipeline(&self.pipeline);
 
             render_pass.set_scissor_rect(
@@ -474,8 +473,6 @@ impl Pipeline {
             render_pass.set_vertex_buffer(0, self.vertices.slice(..));
 
             layer.render(render_pass);
-
-            self.render_layer += 1;
         }
     }
 
@@ -496,7 +493,6 @@ impl Pipeline {
             .trim(&mut self.texture_atlas, &mut (device, queue, encoder));
 
         self.prepare_layer = 0;
-        self.render_layer = 0;
     }
 }
 
diff --git a/wgpu/src/quad.rs b/wgpu/src/quad.rs
index c1aa49c4..246cc5e1 100644
--- a/wgpu/src/quad.rs
+++ b/wgpu/src/quad.rs
@@ -17,7 +17,6 @@ pub struct Pipeline {
     indices: wgpu::Buffer,
     layers: Vec<Layer>,
     prepare_layer: usize,
-    render_layer: usize,
 }
 
 impl Pipeline {
@@ -140,7 +139,6 @@ impl Pipeline {
             indices,
             layers: Vec::new(),
             prepare_layer: 0,
-            render_layer: 0,
         }
     }
 
@@ -163,11 +161,12 @@ impl Pipeline {
     }
 
     pub fn render<'a>(
-        &'a mut self,
+        &'a self,
+        layer: usize,
         bounds: Rectangle<u32>,
         render_pass: &mut wgpu::RenderPass<'a>,
     ) {
-        if let Some(layer) = self.layers.get(self.render_layer) {
+        if let Some(layer) = self.layers.get(layer) {
             render_pass.set_pipeline(&self.pipeline);
 
             render_pass.set_scissor_rect(
@@ -184,14 +183,11 @@ impl Pipeline {
             render_pass.set_vertex_buffer(0, self.vertices.slice(..));
 
             layer.draw(render_pass);
-
-            self.render_layer += 1;
         }
     }
 
     pub fn end_frame(&mut self) {
         self.prepare_layer = 0;
-        self.render_layer = 0;
     }
 }
 
diff --git a/wgpu/src/text.rs b/wgpu/src/text.rs
index 95994a4e..73708fd8 100644
--- a/wgpu/src/text.rs
+++ b/wgpu/src/text.rs
@@ -16,7 +16,7 @@ pub struct Pipeline {
     system: Option<System>,
     renderers: Vec<glyphon::TextRenderer>,
     atlas: glyphon::TextAtlas,
-    layer: usize,
+    prepare_layer: usize,
 }
 
 #[ouroboros::self_referencing]
@@ -55,7 +55,7 @@ impl Pipeline {
             ),
             renderers: Vec::new(),
             atlas: glyphon::TextAtlas::new(device, queue, format),
-            layer: 0,
+            prepare_layer: 0,
         }
     }
 
@@ -88,12 +88,12 @@ impl Pipeline {
         target_size: Size<u32>,
     ) {
         self.system.as_mut().unwrap().with_mut(|fields| {
-            if self.renderers.len() <= self.layer {
+            if self.renderers.len() <= self.prepare_layer {
                 self.renderers
                     .push(glyphon::TextRenderer::new(device, queue));
             }
 
-            let renderer = &mut self.renderers[self.layer];
+            let renderer = &mut self.renderers[self.prepare_layer];
 
             let keys: Vec<_> = sections
                 .iter()
@@ -179,35 +179,21 @@ impl Pipeline {
                     &mut glyphon::SwashCache::new(fields.fonts),
                 )
                 .expect("Prepare text sections");
+
+            self.prepare_layer += 1;
         });
     }
 
-    pub fn render(
-        &mut self,
-        encoder: &mut wgpu::CommandEncoder,
-        target: &wgpu::TextureView,
+    pub fn render<'a>(
+        &'a self,
+        layer: usize,
+        render_pass: &mut wgpu::RenderPass<'a>,
     ) {
-        let mut render_pass =
-            encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
-                label: None,
-                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
-                    view: target,
-                    resolve_target: None,
-                    ops: wgpu::Operations {
-                        load: wgpu::LoadOp::Load,
-                        store: true,
-                    },
-                })],
-                depth_stencil_attachment: None,
-            });
-
-        let renderer = &mut self.renderers[self.layer];
+        let renderer = &self.renderers[layer];
 
         renderer
-            .render(&self.atlas, &mut render_pass)
+            .render(&self.atlas, render_pass)
             .expect("Render text");
-
-        self.layer += 1;
     }
 
     pub fn end_frame(&mut self) {
@@ -216,7 +202,7 @@ impl Pipeline {
             .unwrap()
             .with_render_cache_mut(|cache| cache.trim());
 
-        self.layer = 0;
+        self.prepare_layer = 0;
     }
 
     pub fn measure(
diff --git a/wgpu/src/triangle.rs b/wgpu/src/triangle.rs
index 572af1e8..1b537bf4 100644
--- a/wgpu/src/triangle.rs
+++ b/wgpu/src/triangle.rs
@@ -22,7 +22,6 @@ pub struct Pipeline {
 
     layers: Vec<Layer>,
     prepare_layer: usize,
-    render_layer: usize,
 }
 
 #[derive(Debug)]
@@ -235,7 +234,7 @@ impl Layer {
     }
 
     fn render<'a>(
-        &'a mut self,
+        &'a self,
         solid: &'a solid::Pipeline,
         #[cfg(not(target_arch = "wasm32"))] gradient: &'a gradient::Pipeline,
         meshes: &[Mesh<'_>],
@@ -331,7 +330,6 @@ impl Pipeline {
 
             layers: Vec::new(),
             prepare_layer: 0,
-            render_layer: 0,
         }
     }
 
@@ -373,6 +371,7 @@ impl Pipeline {
         device: &wgpu::Device,
         encoder: &mut wgpu::CommandEncoder,
         target: &wgpu::TextureView,
+        layer: usize,
         target_size: Size<u32>,
         meshes: &[Mesh<'_>],
         scale_factor: f32,
@@ -413,7 +412,7 @@ impl Pipeline {
                     depth_stencil_attachment: None,
                 });
 
-            let layer = &mut self.layers[self.render_layer];
+            let layer = &mut self.layers[layer];
 
             layer.render(
                 &self.solid,
@@ -425,8 +424,6 @@ impl Pipeline {
             );
         }
 
-        self.render_layer += 1;
-
         if let Some(blit) = &mut self.blit {
             blit.draw(encoder, target);
         }
@@ -434,7 +431,6 @@ impl Pipeline {
 
     pub fn end_frame(&mut self) {
         self.prepare_layer = 0;
-        self.render_layer = 0;
     }
 }
 
diff --git a/wgpu/src/window/compositor.rs b/wgpu/src/window/compositor.rs
index 6e1acc06..365cb603 100644
--- a/wgpu/src/window/compositor.rs
+++ b/wgpu/src/window/compositor.rs
@@ -190,39 +190,12 @@ impl<Theme> iced_graphics::window::Compositor for Compositor<Theme> {
                     .texture
                     .create_view(&wgpu::TextureViewDescriptor::default());
 
-                let _ =
-                    encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
-                        label: Some(
-                            "iced_wgpu::window::Compositor render pass",
-                        ),
-                        color_attachments: &[Some(
-                            wgpu::RenderPassColorAttachment {
-                                view,
-                                resolve_target: None,
-                                ops: wgpu::Operations {
-                                    load: wgpu::LoadOp::Clear({
-                                        let [r, g, b, a] =
-                                            background_color.into_linear();
-
-                                        wgpu::Color {
-                                            r: f64::from(r),
-                                            g: f64::from(g),
-                                            b: f64::from(b),
-                                            a: f64::from(a),
-                                        }
-                                    }),
-                                    store: true,
-                                },
-                            },
-                        )],
-                        depth_stencil_attachment: None,
-                    });
-
                 renderer.with_primitives(|backend, primitives| {
                     backend.present(
                         &self.device,
                         &self.queue,
                         &mut encoder,
+                        Some(background_color),
                         view,
                         primitives,
                         viewport,