Provide actual bounds to Shader primitives

... and allow for proper translation and scissoring.

wgpu/src/backend.rs

@@ -192,9 +192,9 @@ impl Backend {
                         format,
                         device,
                         queue,
+                        pipeline.bounds,
                         target_size,
                         scale_factor,
-                        transformation,
                         &mut self.pipeline_storage,
                     );
                 }
@@ -327,17 +327,17 @@ impl Backend {
                 let _ = ManuallyDrop::into_inner(render_pass);
 
                 for pipeline in &layer.pipelines {
-                    let bounds = (pipeline.bounds * scale_factor).snap();
+                    let viewport = (pipeline.viewport * scale_factor).snap();
 
-                    if bounds.width < 1 || bounds.height < 1 {
+                    if viewport.width < 1 || viewport.height < 1 {
                         continue;
                     }
 
                     pipeline.primitive.render(
                         &self.pipeline_storage,
-                        bounds,
                         target,
                         target_size,
+                        viewport,
                         encoder,
                     );
                 }

wgpu/src/layer.rs

@@ -1,11 +1,13 @@
 //! Organize rendering primitives into a flattened list of layers.
 mod image;
+mod pipeline;
 mod text;
 
 pub mod mesh;
 
 pub use image::Image;
 pub use mesh::Mesh;
+pub use pipeline::Pipeline;
 pub use text::Text;
 
 use crate::core;
@@ -36,7 +38,7 @@ pub struct Layer<'a> {
     pub images: Vec<Image>,
 
     /// The custom pipelines of this [`Layer`].
-    pub pipelines: Vec<primitive::Pipeline>,
+    pub pipelines: Vec<Pipeline>,
 }
 
 impl<'a> Layer<'a> {
@@ -314,17 +316,14 @@ impl<'a> Layer<'a> {
                 },
                 primitive::Custom::Pipeline(pipeline) => {
                     let layer = &mut layers[current_layer];
-
-                    let bounds = Rectangle::new(
-                        Point::new(translation.x, translation.y),
-                        pipeline.bounds.size(),
-                    );
+                    let bounds = pipeline.bounds + translation;
 
                     if let Some(clip_bounds) =
                         layer.bounds.intersection(&bounds)
                     {
-                        layer.pipelines.push(primitive::Pipeline {
-                            bounds: clip_bounds,
+                        layer.pipelines.push(Pipeline {
+                            bounds,
+                            viewport: clip_bounds,
                             primitive: pipeline.primitive.clone(),
                         });
                     }

wgpu/src/layer/pipeline.rs

@@ -0,0 +1,17 @@
+use crate::core::Rectangle;
+use crate::primitive::pipeline::Primitive;
+
+use std::sync::Arc;
+
+#[derive(Clone, Debug)]
+/// A custom primitive which can be used to render primitives associated with a custom pipeline.
+pub struct Pipeline {
+    /// The bounds of the [`Pipeline`].
+    pub bounds: Rectangle,
+
+    /// The viewport of the [`Pipeline`].
+    pub viewport: Rectangle,
+
+    /// The [`Primitive`] to render.
+    pub primitive: Arc<dyn Primitive>,
+}

wgpu/src/primitive/pipeline.rs

@@ -1,6 +1,5 @@
 //! Draw primitives using custom pipelines.
 use crate::core::{Rectangle, Size};
-use crate::graphics::Transformation;
 
 use std::any::{Any, TypeId};
 use std::collections::HashMap;
@@ -41,9 +40,9 @@ pub trait Primitive: Debug + Send + Sync + 'static {
         format: wgpu::TextureFormat,
         device: &wgpu::Device,
         queue: &wgpu::Queue,
+        bounds: Rectangle,
         target_size: Size<u32>,
         scale_factor: f32,
-        transform: Transformation,
         storage: &mut Storage,
     );
 
@@ -51,9 +50,9 @@ pub trait Primitive: Debug + Send + Sync + 'static {
     fn render(
         &self,
         storage: &Storage,
-        bounds: Rectangle<u32>,
         target: &wgpu::TextureView,
         target_size: Size<u32>,
+        viewport: Rectangle<u32>,
         encoder: &mut wgpu::CommandEncoder,
     );
 }