Clip and cull `Mesh2D` primitives in `iced_wgpu`

4 files changed, 44 insertions, 25 deletions

diff --git a/wgpu/src/primitive.rs b/wgpu/src/primitive.rs
index e9c0bf46..e73227ef 100644
--- a/wgpu/src/primitive.rs
+++ b/wgpu/src/primitive.rs
@@ -1,5 +1,5 @@
 use iced_native::{
-    image, svg, Background, Color, Font, HorizontalAlignment, Rectangle,
+    image, svg, Background, Color, Font, HorizontalAlignment, Rectangle, Size,
     Vector, VerticalAlignment,
 };
 
@@ -72,7 +72,7 @@ pub enum Primitive {
     },
     /// A primitive that applies a translation
     Translate {
-        /// The top-left coordinate of the mesh
+        /// The translation vector
         translation: Vector,
 
         /// The primitive to translate
@@ -82,6 +82,11 @@ pub enum Primitive {
     ///
     /// It can be used to render many kinds of geometry freely.
     Mesh2D {
+        /// The size of the drawable region of the mesh.
+        ///
+        /// Any geometry that falls out of this region will be clipped.
+        size: Size,
+
         /// The vertex and index buffers of the mesh
         buffers: triangle::Mesh2D,
     },
diff --git a/wgpu/src/renderer.rs b/wgpu/src/renderer.rs
index e93532bc..5c38ce61 100644
--- a/wgpu/src/renderer.rs
+++ b/wgpu/src/renderer.rs
@@ -29,7 +29,7 @@ pub struct Renderer {
 struct Layer<'a> {
     bounds: Rectangle<u32>,
     quads: Vec<Quad>,
-    meshes: Vec<(Vector, &'a triangle::Mesh2D)>,
+    meshes: Vec<(Vector, Rectangle<u32>, &'a triangle::Mesh2D)>,
     text: Vec<wgpu_glyph::Section<'a>>,
 
     #[cfg(any(feature = "image", feature = "svg"))]
@@ -48,6 +48,12 @@ impl<'a> Layer<'a> {
             images: Vec::new(),
         }
     }
+
+    pub fn intersection(&self, rectangle: Rectangle) -> Option<Rectangle<u32>> {
+        let layer_bounds: Rectangle<f32> = self.bounds.into();
+
+        layer_bounds.intersection(&rectangle).map(Into::into)
+    }
 }
 
 impl Renderer {
@@ -214,10 +220,20 @@ impl Renderer {
                     border_color: border_color.into_linear(),
                 });
             }
-            Primitive::Mesh2D { buffers } => {
+            Primitive::Mesh2D { size, buffers } => {
                 let layer = layers.last_mut().unwrap();
 
-                layer.meshes.push((translation, buffers));
+                // Only draw visible content
+                if let Some(clip_bounds) = layer.intersection(Rectangle::new(
+                    Point::new(translation.x, translation.y),
+                    *size,
+                )) {
+                    layer.meshes.push((
+                        translation,
+                        clip_bounds.into(),
+                        buffers,
+                    ));
+                }
             }
             Primitive::Clip {
                 bounds,
@@ -226,16 +242,10 @@ impl Renderer {
             } => {
                 let layer = layers.last_mut().unwrap();
 
-                let layer_bounds: Rectangle<f32> = layer.bounds.into();
-
-                let clip = Rectangle {
-                    x: bounds.x + translation.x,
-                    y: bounds.y + translation.y,
-                    ..*bounds
-                };
-
                 // Only draw visible content
-                if let Some(clip_bounds) = layer_bounds.intersection(&clip) {
+                if let Some(clip_bounds) =
+                    layer.intersection(*bounds + translation)
+                {
                     let clip_layer = Layer::new(clip_bounds.into());
                     let new_layer = Layer::new(layer.bounds);
 
@@ -356,8 +366,8 @@ impl Renderer {
                 target_width,
                 target_height,
                 scaled,
+                scale_factor,
                 &layer.meshes,
-                bounds,
             );
         }
 
diff --git a/wgpu/src/triangle.rs b/wgpu/src/triangle.rs
index b58cc03c..246dc7ce 100644
--- a/wgpu/src/triangle.rs
+++ b/wgpu/src/triangle.rs
@@ -201,15 +201,15 @@ impl Pipeline {
         target_width: u32,
         target_height: u32,
         transformation: Transformation,
-        meshes: &[(Vector, &Mesh2D)],
-        bounds: Rectangle<u32>,
+        scale_factor: f32,
+        meshes: &[(Vector, Rectangle<u32>, &Mesh2D)],
     ) {
         // This looks a bit crazy, but we are just counting how many vertices
         // and indices we will need to handle.
         // TODO: Improve readability
         let (total_vertices, total_indices) = meshes
             .iter()
-            .map(|(_, mesh)| (mesh.vertices.len(), mesh.indices.len()))
+            .map(|(_, _, mesh)| (mesh.vertices.len(), mesh.indices.len()))
             .fold((0, 0), |(total_v, total_i), (v, i)| {
                 (total_v + v, total_i + i)
             });
@@ -230,7 +230,7 @@ impl Pipeline {
         let mut last_index = 0;
 
         // We upload everything upfront
-        for (origin, mesh) in meshes {
+        for (origin, _, mesh) in meshes {
             let transform = (transformation
                 * Transformation::translate(origin.x, origin.y))
             .into();
@@ -316,16 +316,19 @@ impl Pipeline {
                 });
 
             render_pass.set_pipeline(&self.pipeline);
-            render_pass.set_scissor_rect(
-                bounds.x,
-                bounds.y,
-                bounds.width,
-                bounds.height,
-            );
 
             for (i, (vertex_offset, index_offset, indices)) in
                 offsets.into_iter().enumerate()
             {
+                let bounds = meshes[i].1 * scale_factor;
+
+                render_pass.set_scissor_rect(
+                    bounds.x,
+                    bounds.y,
+                    bounds.width,
+                    bounds.height,
+                );
+
                 render_pass.set_bind_group(
                     0,
                     &self.constants,
diff --git a/wgpu/src/widget/canvas/frame.rs b/wgpu/src/widget/canvas/frame.rs
index 8623ce4d..1c4a038a 100644
--- a/wgpu/src/widget/canvas/frame.rs
+++ b/wgpu/src/widget/canvas/frame.rs
@@ -267,6 +267,7 @@ impl Frame {
     pub fn into_geometry(mut self) -> Geometry {
         if !self.buffers.indices.is_empty() {
             self.primitives.push(Primitive::Mesh2D {
+                size: self.size,
                 buffers: triangle::Mesh2D {
                     vertices: self.buffers.vertices,
                     indices: self.buffers.indices,