src/lib.rs - external/github.com/linebender/vello - Git at Google

 // Copyright 2022 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 //
 // Also licensed under MIT license, at your choice.

 mod engine;
 mod render;
 mod scene;
 mod shaders;

 /// Styling and composition primitives.
 pub use peniko;
 /// 2D geometry, with a focus on curves.
 pub use peniko::kurbo;

 pub mod encoding;

 pub mod glyph;
 pub mod util;

 pub use scene::{Scene, SceneBuilder, SceneFragment};

 use engine::{Engine, ExternalResource};
 use shaders::FullShaders;

 use wgpu::{Device, Queue, SurfaceTexture, TextureFormat, TextureView};

 /// Catch-all error type.
 pub type Error = Box<dyn std::error::Error>;

 /// Specialization of `Result` for our catch-all error type.
 pub type Result<T> = std::result::Result<T, Error>;

 /// Renders a scene into a texture or surface.
 pub struct Renderer {
     engine: Engine,
     shaders: FullShaders,
     blit: BlitPipeline,
     target: Option<TargetTexture>,
 }

 impl Renderer {
     /// Creates a new renderer for the specified device.
     pub fn new(device: &Device) -> Result<Self> {
         let mut engine = Engine::new();
         let shaders = shaders::full_shaders(device, &mut engine)?;
         let blit = BlitPipeline::new(device, TextureFormat::Bgra8Unorm);
         Ok(Self {
             engine,
             shaders,
             blit,
             target: None,
         })
     }

     /// Renders a scene to the target texture.
     ///
     /// The texture is assumed to be of the specified dimensions and have been created with
     /// the [wgpu::TextureFormat::Rgba8Unorm] format and the [wgpu::TextureUsages::STORAGE_BINDING]
     /// flag set.
     pub fn render_to_texture(
         &mut self,
         device: &Device,
         queue: &Queue,
         scene: &Scene,
         texture: &TextureView,
         width: u32,
         height: u32,
     ) -> Result<()> {
         let (recording, target) = render::render_full(&scene, &self.shaders, width, height);
         let external_resources = [ExternalResource::Image(
             *target.as_image().unwrap(),
             texture,
         )];
         let _ = self
             .engine
             .run_recording(device, queue, &recording, &external_resources)?;
         Ok(())
     }

     /// Renders a scene to the target surface.
     ///
     /// This renders to an intermediate texture and then runs a render pass to blit to the
     /// specified surface texture.
     ///
     /// The surface is assumed to be of the specified dimensions and have been created with the
     /// [wgpu::TextureFormat::Bgra8Unorm] format.
     pub fn render_to_surface(
         &mut self,
         device: &Device,
         queue: &Queue,
         scene: &Scene,
         surface: &SurfaceTexture,
         width: u32,
         height: u32,
     ) -> Result<()> {
         let mut target = self
             .target
             .take()
             .unwrap_or_else(|| TargetTexture::new(device, width, height));
         // TODO: implement clever resizing semantics here to avoid thrashing the memory allocator
         // during resize, specifically on metal.
         if target.width != width || target.height != height {
             target = TargetTexture::new(device, width, height);
         }
         self.render_to_texture(device, queue, scene, &target.view, width, height)?;
         let mut encoder =
             device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
         {
             let surface_view = surface
                 .texture
                 .create_view(&wgpu::TextureViewDescriptor::default());
             let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
                 label: None,
                 layout: &self.blit.bind_layout,
                 entries: &[wgpu::BindGroupEntry {
                     binding: 0,
                     resource: wgpu::BindingResource::TextureView(&target.view),
                 }],
             });
             let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                 label: None,
                 color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                     view: &surface_view,
                     resolve_target: None,
                     ops: wgpu::Operations {
                         load: wgpu::LoadOp::Clear(wgpu::Color::default()),
                         store: true,
                     },
                 })],
                 depth_stencil_attachment: None,
             });
             render_pass.set_pipeline(&self.blit.pipeline);
             render_pass.set_bind_group(0, &bind_group, &[]);
             render_pass.draw(0..6, 0..1);
         }
         queue.submit(Some(encoder.finish()));
         self.target = Some(target);
         Ok(())
     }
 }

 struct TargetTexture {
     view: TextureView,
     width: u32,
     height: u32,
 }

 impl TargetTexture {
     pub fn new(device: &Device, width: u32, height: u32) -> Self {
         let texture = device.create_texture(&wgpu::TextureDescriptor {
             label: None,
             size: wgpu::Extent3d {
                 width,
                 height,
                 depth_or_array_layers: 1,
             },
             mip_level_count: 1,
             sample_count: 1,
             dimension: wgpu::TextureDimension::D2,
             usage: wgpu::TextureUsages::STORAGE_BINDING | wgpu::TextureUsages::TEXTURE_BINDING,
             format: wgpu::TextureFormat::Rgba8Unorm,
         });
         let view = texture.create_view(&wgpu::TextureViewDescriptor::default());
         Self {
             view,
             width,
             height,
         }
     }
 }

 struct BlitPipeline {
     bind_layout: wgpu::BindGroupLayout,
     pipeline: wgpu::RenderPipeline,
 }

 impl BlitPipeline {
     fn new(device: &Device, format: TextureFormat) -> Self {
         const SHADERS: &str = r#"
             @vertex
             fn vs_main(@builtin(vertex_index) ix: u32) -> @builtin(position) vec4<f32> {
                 // Generate a full screen quad in NDCs
                 var vertex = vec2(-1.0, 1.0);
                 switch ix {
                     case 1u: {
                         vertex = vec2(-1.0, -1.0);
                     }
                     case 2u, 4u: {
                         vertex = vec2(1.0, -1.0);
                     }
                     case 5u: {
                         vertex = vec2(1.0, 1.0);
                     }
                     default: {}
                 }
                 return vec4(vertex, 0.0, 1.0);
             }

             @group(0) @binding(0)
             var fine_output: texture_2d<f32>;

             @fragment
             fn fs_main(@builtin(position) pos: vec4<f32>) -> @location(0) vec4<f32> {
                 let rgba_sep = textureLoad(fine_output, vec2<i32>(pos.xy), 0);
                 return vec4(rgba_sep.rgb * rgba_sep.a, rgba_sep.a);
             }
         "#;

         let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
             label: Some("blit shaders"),
             source: wgpu::ShaderSource::Wgsl(SHADERS.into()),
         });
         let bind_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
             label: None,
             entries: &[wgpu::BindGroupLayoutEntry {
                 visibility: wgpu::ShaderStages::FRAGMENT,
                 binding: 0,
                 ty: wgpu::BindingType::Texture {
                     sample_type: wgpu::TextureSampleType::Float { filterable: true },
                     view_dimension: wgpu::TextureViewDimension::D2,
                     multisampled: false,
                 },
                 count: None,
             }],
         });
         let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
             label: None,
             bind_group_layouts: &[&bind_layout],
             push_constant_ranges: &[],
         });
         let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
             label: None,
             layout: Some(&pipeline_layout),
             vertex: wgpu::VertexState {
                 module: &shader,
                 entry_point: "vs_main",
                 buffers: &[],
             },
             fragment: Some(wgpu::FragmentState {
                 module: &shader,
                 entry_point: "fs_main",
                 targets: &[Some(wgpu::ColorTargetState {
                     format,
                     blend: None,
                     write_mask: wgpu::ColorWrites::ALL,
                 })],
             }),
             primitive: wgpu::PrimitiveState {
                 topology: wgpu::PrimitiveTopology::TriangleList,
                 strip_index_format: None,
                 front_face: wgpu::FrontFace::Ccw,
                 cull_mode: Some(wgpu::Face::Back),
                 polygon_mode: wgpu::PolygonMode::Fill,
                 unclipped_depth: false,
                 conservative: false,
             },
             depth_stencil: None,
             multisample: wgpu::MultisampleState {
                 count: 1,
                 mask: !0,
                 alpha_to_coverage_enabled: false,
             },
             multiview: None,
         });
         Self {
             bind_layout,
             pipeline,
         }
     }
 }
	// Copyright 2022 Google LLC
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// https://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.
	//
	// Also licensed under MIT license, at your choice.

	mod engine;
	mod render;
	mod scene;
	mod shaders;

	/// Styling and composition primitives.
	pub use peniko;
	/// 2D geometry, with a focus on curves.
	pub use peniko::kurbo;

	pub mod encoding;

	pub mod glyph;
	pub mod util;

	pub use scene::{Scene, SceneBuilder, SceneFragment};

	use engine::{Engine, ExternalResource};
	use shaders::FullShaders;

	use wgpu::{Device, Queue, SurfaceTexture, TextureFormat, TextureView};

	/// Catch-all error type.
	pub type Error = Box<dyn std::error::Error>;

	/// Specialization of `Result` for our catch-all error type.
	pub type Result<T> = std::result::Result<T, Error>;

	/// Renders a scene into a texture or surface.
	pub struct Renderer {
	engine: Engine,
	shaders: FullShaders,
	blit: BlitPipeline,
	target: Option<TargetTexture>,
	}

	impl Renderer {
	/// Creates a new renderer for the specified device.
	pub fn new(device: &Device) -> Result<Self> {
	let mut engine = Engine::new();
	let shaders = shaders::full_shaders(device, &mut engine)?;
	let blit = BlitPipeline::new(device, TextureFormat::Bgra8Unorm);
	Ok(Self {
	engine,
	shaders,
	blit,
	target: None,
	})
	}

	/// Renders a scene to the target texture.
	///
	/// The texture is assumed to be of the specified dimensions and have been created with
	/// the [wgpu::TextureFormat::Rgba8Unorm] format and the [wgpu::TextureUsages::STORAGE_BINDING]
	/// flag set.
	pub fn render_to_texture(
	&mut self,
	device: &Device,
	queue: &Queue,
	scene: &Scene,
	texture: &TextureView,
	width: u32,
	height: u32,
	) -> Result<()> {
	let (recording, target) = render::render_full(&scene, &self.shaders, width, height);
	let external_resources = [ExternalResource::Image(
	*target.as_image().unwrap(),
	texture,
	)];
	let _ = self
	.engine
	.run_recording(device, queue, &recording, &external_resources)?;
	Ok(())
	}

	/// Renders a scene to the target surface.
	///
	/// This renders to an intermediate texture and then runs a render pass to blit to the
	/// specified surface texture.
	///
	/// The surface is assumed to be of the specified dimensions and have been created with the
	/// [wgpu::TextureFormat::Bgra8Unorm] format.
	pub fn render_to_surface(
	&mut self,
	device: &Device,
	queue: &Queue,
	scene: &Scene,
	surface: &SurfaceTexture,
	width: u32,
	height: u32,
	) -> Result<()> {
	let mut target = self
	.target
	.take()
	.unwrap_or_else(\|\| TargetTexture::new(device, width, height));
	// TODO: implement clever resizing semantics here to avoid thrashing the memory allocator
	// during resize, specifically on metal.
	if target.width != width \|\| target.height != height {
	target = TargetTexture::new(device, width, height);
	}
	self.render_to_texture(device, queue, scene, &target.view, width, height)?;
	let mut encoder =
	device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
	{
	let surface_view = surface
	.texture
	.create_view(&wgpu::TextureViewDescriptor::default());
	let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
	label: None,
	layout: &self.blit.bind_layout,
	entries: &[wgpu::BindGroupEntry {
	binding: 0,
	resource: wgpu::BindingResource::TextureView(&target.view),
	}],
	});
	let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
	label: None,
	color_attachments: &[Some(wgpu::RenderPassColorAttachment {
	view: &surface_view,
	resolve_target: None,
	ops: wgpu::Operations {
	load: wgpu::LoadOp::Clear(wgpu::Color::default()),
	store: true,
	},
	})],
	depth_stencil_attachment: None,
	});
	render_pass.set_pipeline(&self.blit.pipeline);
	render_pass.set_bind_group(0, &bind_group, &[]);
	render_pass.draw(0..6, 0..1);
	}
	queue.submit(Some(encoder.finish()));
	self.target = Some(target);
	Ok(())
	}
	}

	struct TargetTexture {
	view: TextureView,
	width: u32,
	height: u32,
	}

	impl TargetTexture {
	pub fn new(device: &Device, width: u32, height: u32) -> Self {
	let texture = device.create_texture(&wgpu::TextureDescriptor {
	label: None,
	size: wgpu::Extent3d {
	width,
	height,
	depth_or_array_layers: 1,
	},
	mip_level_count: 1,
	sample_count: 1,
	dimension: wgpu::TextureDimension::D2,
	usage: wgpu::TextureUsages::STORAGE_BINDING \| wgpu::TextureUsages::TEXTURE_BINDING,
	format: wgpu::TextureFormat::Rgba8Unorm,
	});
	let view = texture.create_view(&wgpu::TextureViewDescriptor::default());
	Self {
	view,
	width,
	height,
	}
	}
	}

	struct BlitPipeline {
	bind_layout: wgpu::BindGroupLayout,
	pipeline: wgpu::RenderPipeline,
	}

	impl BlitPipeline {
	fn new(device: &Device, format: TextureFormat) -> Self {
	const SHADERS: &str = r#"
	@vertex
	fn vs_main(@builtin(vertex_index) ix: u32) -> @builtin(position) vec4<f32> {
	// Generate a full screen quad in NDCs
	var vertex = vec2(-1.0, 1.0);
	switch ix {
	case 1u: {
	vertex = vec2(-1.0, -1.0);
	}
	case 2u, 4u: {
	vertex = vec2(1.0, -1.0);
	}
	case 5u: {
	vertex = vec2(1.0, 1.0);
	}
	default: {}
	}
	return vec4(vertex, 0.0, 1.0);
	}

	@group(0) @binding(0)
	var fine_output: texture_2d<f32>;

	@fragment
	fn fs_main(@builtin(position) pos: vec4<f32>) -> @location(0) vec4<f32> {
	let rgba_sep = textureLoad(fine_output, vec2<i32>(pos.xy), 0);
	return vec4(rgba_sep.rgb * rgba_sep.a, rgba_sep.a);
	}
	"#;

	let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
	label: Some("blit shaders"),
	source: wgpu::ShaderSource::Wgsl(SHADERS.into()),
	});
	let bind_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
	label: None,
	entries: &[wgpu::BindGroupLayoutEntry {
	visibility: wgpu::ShaderStages::FRAGMENT,
	binding: 0,
	ty: wgpu::BindingType::Texture {
	sample_type: wgpu::TextureSampleType::Float { filterable: true },
	view_dimension: wgpu::TextureViewDimension::D2,
	multisampled: false,
	},
	count: None,
	}],
	});
	let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
	label: None,
	bind_group_layouts: &[&bind_layout],
	push_constant_ranges: &[],
	});
	let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
	label: None,
	layout: Some(&pipeline_layout),
	vertex: wgpu::VertexState {
	module: &shader,
	entry_point: "vs_main",
	buffers: &[],
	},
	fragment: Some(wgpu::FragmentState {
	module: &shader,
	entry_point: "fs_main",
	targets: &[Some(wgpu::ColorTargetState {
	format,
	blend: None,
	write_mask: wgpu::ColorWrites::ALL,
	})],
	}),
	primitive: wgpu::PrimitiveState {
	topology: wgpu::PrimitiveTopology::TriangleList,
	strip_index_format: None,
	front_face: wgpu::FrontFace::Ccw,
	cull_mode: Some(wgpu::Face::Back),
	polygon_mode: wgpu::PolygonMode::Fill,
	unclipped_depth: false,
	conservative: false,
	},
	depth_stencil: None,
	multisample: wgpu::MultisampleState {
	count: 1,
	mask: !0,
	alpha_to_coverage_enabled: false,
	},
	multiview: None,
	});
	Self {
	bind_layout,
	pipeline,
	}
	}
	}