Desktop add viewport texture (#2953)

* Allow rendering viewport texture beneath ui texture

* Add viewport scale

* Update desktop/src/render/fullscreen_texture.wgsl

---------

Co-authored-by: Dennis Kobert <dennis@kobert.dev>

Cargo.lock

@@ -1834,6 +1834,7 @@ dependencies = [
 name = "graphite-desktop"
 version = "0.1.0"
 dependencies = [
+ "bytemuck",
  "cef",
  "dirs",
  "futures",

desktop/Cargo.toml

@@ -28,4 +28,5 @@ cef = { workspace = true }
 include_dir = { workspace = true }
 tracing-subscriber = { workspace = true }
 tracing = { workspace = true }
-dirs = {workspace = true}
+dirs = { workspace = true }
+bytemuck = { workspace = true }

desktop/src/app.rs

@@ -83,7 +83,7 @@ impl ApplicationHandler<CustomEvent> for WinitApp {
 		match event {
 			CustomEvent::UiUpdate(texture) => {
 				if let Some(graphics_state) = self.graphics_state.as_mut() {
-					graphics_state.bind_texture(&texture);
+					graphics_state.bind_ui_texture(&texture);
 					graphics_state.resize(texture.width(), texture.height());
 				}
 				if let Some(window) = &self.window {

desktop/src/render.rs

@@ -1,5 +1,6 @@
 use std::sync::Arc;
 
+use bytemuck::{Pod, Zeroable};
 use thiserror::Error;
 use winit::window::Window;
 
@@ -79,13 +80,15 @@ impl WgpuContext {
 			.await
 			.unwrap();
 
+		let required_limits = adapter.limits();
+
 		let (device, queue) = adapter
 			.request_device(&wgpu::DeviceDescriptor {
-				required_features: wgpu::Features::empty(),
-				required_limits: wgpu::Limits::default(),
 				label: None,
+				required_features: wgpu::Features::PUSH_CONSTANTS,
+				required_limits,
 				memory_hints: Default::default(),
-				..Default::default()
+				trace: wgpu::Trace::Off,
 			})
 			.await
 			.unwrap();
@@ -99,10 +102,13 @@ pub(crate) struct GraphicsState {
 	surface: wgpu::Surface<'static>,
 	context: WgpuContext,
 	config: wgpu::SurfaceConfiguration,
-	texture: Option<wgpu::Texture>,
-	bind_group: Option<wgpu::BindGroup>,
 	render_pipeline: wgpu::RenderPipeline,
 	sampler: wgpu::Sampler,
+	viewport_scale: [f32; 2],
+	viewport_offset: [f32; 2],
+	viewport_texture: Option<wgpu::Texture>,
+	ui_texture: Option<wgpu::Texture>,
+	bind_group: Option<wgpu::BindGroup>,
 }
 
 impl GraphicsState {
@@ -156,6 +162,16 @@ impl GraphicsState {
 				wgpu::BindGroupLayoutEntry {
 					binding: 1,
 					visibility: wgpu::ShaderStages::FRAGMENT,
+					ty: wgpu::BindingType::Texture {
+						multisampled: false,
+						view_dimension: wgpu::TextureViewDimension::D2,
+						sample_type: wgpu::TextureSampleType::Float { filterable: true },
+					},
+					count: None,
+				},
+				wgpu::BindGroupLayoutEntry {
+					binding: 2,
+					visibility: wgpu::ShaderStages::FRAGMENT,
 					ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
 					count: None,
 				},
@@ -166,7 +182,10 @@ impl GraphicsState {
 		let render_pipeline_layout = context.device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
 			label: Some("Render Pipeline Layout"),
 			bind_group_layouts: &[&texture_bind_group_layout],
-			push_constant_ranges: &[],
+			push_constant_ranges: &[wgpu::PushConstantRange {
+				stages: wgpu::ShaderStages::FRAGMENT,
+				range: 0..size_of::<Constants>() as u32,
+			}],
 		});
 
 		let render_pipeline = context.device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
@@ -211,10 +230,13 @@ impl GraphicsState {
 			surface,
 			context,
 			config,
-			texture: None,
-			bind_group: None,
 			render_pipeline,
 			sampler,
+			viewport_scale: [1.0, 1.0],
+			viewport_offset: [0.0, 0.0],
+			viewport_texture: None,
+			ui_texture: None,
+			bind_group: None,
 		}
 	}
 
@@ -226,25 +248,47 @@ impl GraphicsState {
 		}
 	}
 
-	pub(crate) fn bind_texture(&mut self, texture: &wgpu::Texture) {
-		let bind_group = self.create_bindgroup(texture);
-		self.texture = Some(texture.clone());
+	pub(crate) fn bind_ui_texture(&mut self, texture: &wgpu::Texture) {
+		let bind_group = self.create_bindgroup(texture, &self.viewport_texture.clone().unwrap_or(texture.clone()));
+
+		self.ui_texture = Some(texture.clone());
 
 		self.bind_group = Some(bind_group);
 	}
 
-	fn create_bindgroup(&self, texture: &wgpu::Texture) -> wgpu::BindGroup {
-		let texture_view = texture.create_view(&wgpu::TextureViewDescriptor::default());
+	pub(crate) fn bind_viewport_texture(&mut self, texture: &wgpu::Texture) {
+		let bind_group = self.create_bindgroup(&self.ui_texture.clone().unwrap_or(texture.clone()), texture);
+
+		self.viewport_texture = Some(texture.clone());
+
+		self.bind_group = Some(bind_group);
+	}
+
+	pub(crate) fn set_viewport_scale(&mut self, scale: [f32; 2]) {
+		self.viewport_scale = scale;
+	}
+
+	pub(crate) fn set_viewport_offset(&mut self, offset: [f32; 2]) {
+		self.viewport_offset = offset;
+	}
+
+	fn create_bindgroup(&self, ui_texture: &wgpu::Texture, viewport_texture: &wgpu::Texture) -> wgpu::BindGroup {
+		let ui_texture_view = ui_texture.create_view(&wgpu::TextureViewDescriptor::default());
+		let viewport_texture_view = viewport_texture.create_view(&wgpu::TextureViewDescriptor::default());
 
 		self.context.device.create_bind_group(&wgpu::BindGroupDescriptor {
 			layout: &self.render_pipeline.get_bind_group_layout(0),
 			entries: &[
 				wgpu::BindGroupEntry {
 					binding: 0,
-					resource: wgpu::BindingResource::TextureView(&texture_view),
+					resource: wgpu::BindingResource::TextureView(&ui_texture_view),
 				},
 				wgpu::BindGroupEntry {
 					binding: 1,
+					resource: wgpu::BindingResource::TextureView(&viewport_texture_view),
+				},
+				wgpu::BindGroupEntry {
+					binding: 2,
 					resource: wgpu::BindingResource::Sampler(&self.sampler),
 				},
 			],
@@ -275,6 +319,14 @@ impl GraphicsState {
 			});
 
 			render_pass.set_pipeline(&self.render_pipeline);
+			render_pass.set_push_constants(
+				wgpu::ShaderStages::FRAGMENT,
+				0,
+				bytemuck::bytes_of(&Constants {
+					viewport_scale: self.viewport_scale,
+					viewport_offset: self.viewport_offset,
+				}),
+			);
 			if let Some(bind_group) = &self.bind_group {
 				render_pass.set_bind_group(0, bind_group, &[]);
 				render_pass.draw(0..6, 0..1); // Draw 3 vertices for fullscreen triangle
@@ -288,3 +340,10 @@ impl GraphicsState {
 		Ok(())
 	}
 }
+
+#[repr(C)]
+#[derive(Copy, Clone, Pod, Zeroable)]
+struct Constants {
+	viewport_scale: [f32; 2],
+	viewport_offset: [f32; 2],
+}

desktop/src/render/fullscreen_texture.wgsl

@@ -25,12 +25,27 @@ fn vs_main(@builtin(vertex_index) vertex_index: u32) -> VertexOutput {
 	return out;
 }
 
+struct Constants {
+	viewport_scale: vec2<f32>,
+	viewport_offset: vec2<f32>,
+};
+
+var<push_constant> constants: Constants;
+
 @group(0) @binding(0)
-var t_diffuse: texture_2d<f32>;
+var t_ui: texture_2d<f32>;
 @group(0) @binding(1)
+var t_viewport: texture_2d<f32>;
+@group(0) @binding(2)
 var s_diffuse: sampler;
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
-	return textureSample(t_diffuse, s_diffuse, in.tex_coords);
+	let ui_color: vec4<f32> = textureSample(t_ui, s_diffuse, in.tex_coords);
+	if (ui_color.a == 1.0) {
+		return ui_color;
+	}
+	let viewport_tex_coords = (in.tex_coords - constants.viewport_offset) * constants.viewport_scale;
+	let viewport_color: vec4<f32> = textureSample(t_viewport, s_diffuse, viewport_tex_coords);
+	return ui_color * ui_color.a + viewport_color * (1.0 - ui_color.a);
 }