364 lines
13 KiB
Rust
364 lines
13 KiB
Rust
//! This example shows how to manually render 2d items using "mid level render apis" with a custom
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//! pipeline for 2d meshes.
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//! It doesn't use the [`Material2d`] abstraction, but changes the vertex buffer to include vertex color.
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//! Check out the "mesh2d" example for simpler / higher level 2d meshes.
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use std::f32::consts::PI;
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use bevy::{
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core_pipeline::core_2d::Transparent2d,
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prelude::*,
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reflect::TypeUuid,
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render::{
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mesh::{Indices, MeshVertexAttribute},
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render_asset::RenderAssets,
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render_phase::{AddRenderCommand, DrawFunctions, RenderPhase, SetItemPipeline},
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render_resource::{
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BlendState, ColorTargetState, ColorWrites, Face, FragmentState, FrontFace,
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MultisampleState, PipelineCache, PolygonMode, PrimitiveState, PrimitiveTopology,
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RenderPipelineDescriptor, SpecializedRenderPipeline, SpecializedRenderPipelines,
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TextureFormat, VertexBufferLayout, VertexFormat, VertexState, VertexStepMode,
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},
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texture::BevyDefault,
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view::{ExtractedView, ViewTarget, VisibleEntities},
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Extract, Render, RenderApp, RenderSet,
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},
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sprite::{
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DrawMesh2d, Mesh2dHandle, Mesh2dPipeline, Mesh2dPipelineKey, Mesh2dUniform,
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SetMesh2dBindGroup, SetMesh2dViewBindGroup,
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},
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utils::FloatOrd,
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};
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_plugin(ColoredMesh2dPlugin)
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.add_systems(Startup, star)
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.run();
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}
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fn star(
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mut commands: Commands,
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// We will add a new Mesh for the star being created
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mut meshes: ResMut<Assets<Mesh>>,
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) {
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// Let's define the mesh for the object we want to draw: a nice star.
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// We will specify here what kind of topology is used to define the mesh,
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// that is, how triangles are built from the vertices. We will use a
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// triangle list, meaning that each vertex of the triangle has to be
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// specified.
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let mut star = Mesh::new(PrimitiveTopology::TriangleList);
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// Vertices need to have a position attribute. We will use the following
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// vertices (I hope you can spot the star in the schema).
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//
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// 1
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//
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// 10 2
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// 9 0 3
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// 8 4
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// 6
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// 7 5
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//
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// These vertices are specified in 3D space.
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let mut v_pos = vec![[0.0, 0.0, 0.0]];
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for i in 0..10 {
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// The angle between each vertex is 1/10 of a full rotation.
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let a = i as f32 * PI / 5.0;
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// The radius of inner vertices (even indices) is 100. For outer vertices (odd indices) it's 200.
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let r = (1 - i % 2) as f32 * 100.0 + 100.0;
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// Add the vertex position.
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v_pos.push([r * a.sin(), r * a.cos(), 0.0]);
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}
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// Set the position attribute
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star.insert_attribute(Mesh::ATTRIBUTE_POSITION, v_pos);
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// And a RGB color attribute as well
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let mut v_color: Vec<u32> = vec![Color::BLACK.as_linear_rgba_u32()];
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v_color.extend_from_slice(&[Color::YELLOW.as_linear_rgba_u32(); 10]);
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star.insert_attribute(
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MeshVertexAttribute::new("Vertex_Color", 1, VertexFormat::Uint32),
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v_color,
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);
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// Now, we specify the indices of the vertex that are going to compose the
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// triangles in our star. Vertices in triangles have to be specified in CCW
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// winding (that will be the front face, colored). Since we are using
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// triangle list, we will specify each triangle as 3 vertices
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// First triangle: 0, 2, 1
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// Second triangle: 0, 3, 2
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// Third triangle: 0, 4, 3
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// etc
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// Last triangle: 0, 1, 10
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let mut indices = vec![0, 1, 10];
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for i in 2..=10 {
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indices.extend_from_slice(&[0, i, i - 1]);
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}
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star.set_indices(Some(Indices::U32(indices)));
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// We can now spawn the entities for the star and the camera
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commands.spawn((
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// We use a marker component to identify the custom colored meshes
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ColoredMesh2d::default(),
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// The `Handle<Mesh>` needs to be wrapped in a `Mesh2dHandle` to use 2d rendering instead of 3d
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Mesh2dHandle(meshes.add(star)),
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// This bundle's components are needed for something to be rendered
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SpatialBundle::INHERITED_IDENTITY,
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));
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// Spawn the camera
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commands.spawn(Camera2dBundle::default());
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}
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/// A marker component for colored 2d meshes
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#[derive(Component, Default)]
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pub struct ColoredMesh2d;
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/// Custom pipeline for 2d meshes with vertex colors
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#[derive(Resource)]
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pub struct ColoredMesh2dPipeline {
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/// this pipeline wraps the standard [`Mesh2dPipeline`]
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mesh2d_pipeline: Mesh2dPipeline,
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}
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impl FromWorld for ColoredMesh2dPipeline {
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fn from_world(world: &mut World) -> Self {
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Self {
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mesh2d_pipeline: Mesh2dPipeline::from_world(world),
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}
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}
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}
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// We implement `SpecializedPipeline` to customize the default rendering from `Mesh2dPipeline`
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impl SpecializedRenderPipeline for ColoredMesh2dPipeline {
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type Key = Mesh2dPipelineKey;
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fn specialize(&self, key: Self::Key) -> RenderPipelineDescriptor {
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// Customize how to store the meshes' vertex attributes in the vertex buffer
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// Our meshes only have position and color
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let formats = vec![
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// Position
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VertexFormat::Float32x3,
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// Color
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VertexFormat::Uint32,
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];
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let vertex_layout =
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VertexBufferLayout::from_vertex_formats(VertexStepMode::Vertex, formats);
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let format = match key.contains(Mesh2dPipelineKey::HDR) {
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true => ViewTarget::TEXTURE_FORMAT_HDR,
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false => TextureFormat::bevy_default(),
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};
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RenderPipelineDescriptor {
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vertex: VertexState {
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// Use our custom shader
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shader: COLORED_MESH2D_SHADER_HANDLE.typed::<Shader>(),
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entry_point: "vertex".into(),
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shader_defs: Vec::new(),
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// Use our custom vertex buffer
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buffers: vec![vertex_layout],
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},
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fragment: Some(FragmentState {
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// Use our custom shader
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shader: COLORED_MESH2D_SHADER_HANDLE.typed::<Shader>(),
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shader_defs: Vec::new(),
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entry_point: "fragment".into(),
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targets: vec![Some(ColorTargetState {
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format,
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blend: Some(BlendState::ALPHA_BLENDING),
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write_mask: ColorWrites::ALL,
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})],
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}),
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// Use the two standard uniforms for 2d meshes
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layout: vec![
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// Bind group 0 is the view uniform
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self.mesh2d_pipeline.view_layout.clone(),
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// Bind group 1 is the mesh uniform
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self.mesh2d_pipeline.mesh_layout.clone(),
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],
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push_constant_ranges: Vec::new(),
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primitive: PrimitiveState {
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front_face: FrontFace::Ccw,
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cull_mode: Some(Face::Back),
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unclipped_depth: false,
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polygon_mode: PolygonMode::Fill,
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conservative: false,
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topology: key.primitive_topology(),
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strip_index_format: None,
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},
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depth_stencil: None,
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multisample: MultisampleState {
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count: key.msaa_samples(),
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mask: !0,
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alpha_to_coverage_enabled: false,
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},
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label: Some("colored_mesh2d_pipeline".into()),
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}
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}
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}
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// This specifies how to render a colored 2d mesh
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type DrawColoredMesh2d = (
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// Set the pipeline
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SetItemPipeline,
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// Set the view uniform as bind group 0
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SetMesh2dViewBindGroup<0>,
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// Set the mesh uniform as bind group 1
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SetMesh2dBindGroup<1>,
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// Draw the mesh
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DrawMesh2d,
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);
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// The custom shader can be inline like here, included from another file at build time
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// using `include_str!()`, or loaded like any other asset with `asset_server.load()`.
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const COLORED_MESH2D_SHADER: &str = r"
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// Import the standard 2d mesh uniforms and set their bind groups
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#import bevy_sprite::mesh2d_types
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#import bevy_sprite::mesh2d_view_bindings
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@group(1) @binding(0)
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var<uniform> mesh: Mesh2d;
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// NOTE: Bindings must come before functions that use them!
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#import bevy_sprite::mesh2d_functions
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// The structure of the vertex buffer is as specified in `specialize()`
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struct Vertex {
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@location(0) position: vec3<f32>,
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@location(1) color: u32,
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};
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struct VertexOutput {
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// The vertex shader must set the on-screen position of the vertex
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@builtin(position) clip_position: vec4<f32>,
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// We pass the vertex color to the fragment shader in location 0
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@location(0) color: vec4<f32>,
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};
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/// Entry point for the vertex shader
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@vertex
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fn vertex(vertex: Vertex) -> VertexOutput {
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var out: VertexOutput;
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// Project the world position of the mesh into screen position
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out.clip_position = mesh2d_position_local_to_clip(mesh.model, vec4<f32>(vertex.position, 1.0));
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// Unpack the `u32` from the vertex buffer into the `vec4<f32>` used by the fragment shader
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out.color = vec4<f32>((vec4<u32>(vertex.color) >> vec4<u32>(0u, 8u, 16u, 24u)) & vec4<u32>(255u)) / 255.0;
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return out;
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}
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// The input of the fragment shader must correspond to the output of the vertex shader for all `location`s
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struct FragmentInput {
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// The color is interpolated between vertices by default
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@location(0) color: vec4<f32>,
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};
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/// Entry point for the fragment shader
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@fragment
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fn fragment(in: FragmentInput) -> @location(0) vec4<f32> {
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return in.color;
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}
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";
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/// Plugin that renders [`ColoredMesh2d`]s
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pub struct ColoredMesh2dPlugin;
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/// Handle to the custom shader with a unique random ID
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pub const COLORED_MESH2D_SHADER_HANDLE: HandleUntyped =
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HandleUntyped::weak_from_u64(Shader::TYPE_UUID, 13828845428412094821);
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impl Plugin for ColoredMesh2dPlugin {
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fn build(&self, app: &mut App) {
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// Load our custom shader
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let mut shaders = app.world.resource_mut::<Assets<Shader>>();
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shaders.set_untracked(
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COLORED_MESH2D_SHADER_HANDLE,
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Shader::from_wgsl(COLORED_MESH2D_SHADER),
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);
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// Register our custom draw function and pipeline, and add our render systems
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app.get_sub_app_mut(RenderApp)
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.unwrap()
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.add_render_command::<Transparent2d, DrawColoredMesh2d>()
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.init_resource::<ColoredMesh2dPipeline>()
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.init_resource::<SpecializedRenderPipelines<ColoredMesh2dPipeline>>()
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.add_systems(ExtractSchedule, extract_colored_mesh2d)
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.add_systems(Render, queue_colored_mesh2d.in_set(RenderSet::Queue));
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}
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}
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/// Extract the [`ColoredMesh2d`] marker component into the render app
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pub fn extract_colored_mesh2d(
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mut commands: Commands,
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mut previous_len: Local<usize>,
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// When extracting, you must use `Extract` to mark the `SystemParam`s
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// which should be taken from the main world.
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query: Extract<Query<(Entity, &ComputedVisibility), With<ColoredMesh2d>>>,
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) {
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let mut values = Vec::with_capacity(*previous_len);
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for (entity, computed_visibility) in &query {
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if !computed_visibility.is_visible() {
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continue;
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}
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values.push((entity, ColoredMesh2d));
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}
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*previous_len = values.len();
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commands.insert_or_spawn_batch(values);
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}
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/// Queue the 2d meshes marked with [`ColoredMesh2d`] using our custom pipeline and draw function
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#[allow(clippy::too_many_arguments)]
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pub fn queue_colored_mesh2d(
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transparent_draw_functions: Res<DrawFunctions<Transparent2d>>,
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colored_mesh2d_pipeline: Res<ColoredMesh2dPipeline>,
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mut pipelines: ResMut<SpecializedRenderPipelines<ColoredMesh2dPipeline>>,
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pipeline_cache: Res<PipelineCache>,
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msaa: Res<Msaa>,
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render_meshes: Res<RenderAssets<Mesh>>,
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colored_mesh2d: Query<(&Mesh2dHandle, &Mesh2dUniform), With<ColoredMesh2d>>,
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mut views: Query<(
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&VisibleEntities,
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&mut RenderPhase<Transparent2d>,
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&ExtractedView,
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)>,
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) {
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if colored_mesh2d.is_empty() {
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return;
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}
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// Iterate each view (a camera is a view)
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for (visible_entities, mut transparent_phase, view) in &mut views {
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let draw_colored_mesh2d = transparent_draw_functions.read().id::<DrawColoredMesh2d>();
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let mesh_key = Mesh2dPipelineKey::from_msaa_samples(msaa.samples())
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| Mesh2dPipelineKey::from_hdr(view.hdr);
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// Queue all entities visible to that view
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for visible_entity in &visible_entities.entities {
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if let Ok((mesh2d_handle, mesh2d_uniform)) = colored_mesh2d.get(*visible_entity) {
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// Get our specialized pipeline
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let mut mesh2d_key = mesh_key;
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if let Some(mesh) = render_meshes.get(&mesh2d_handle.0) {
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mesh2d_key |=
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Mesh2dPipelineKey::from_primitive_topology(mesh.primitive_topology);
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}
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let pipeline_id =
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pipelines.specialize(&pipeline_cache, &colored_mesh2d_pipeline, mesh2d_key);
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let mesh_z = mesh2d_uniform.transform.w_axis.z;
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transparent_phase.add(Transparent2d {
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entity: *visible_entity,
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draw_function: draw_colored_mesh2d,
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pipeline: pipeline_id,
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// The 2d render items are sorted according to their z value before rendering,
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// in order to get correct transparency
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sort_key: FloatOrd(mesh_z),
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// This material is not batched
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batch_range: None,
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});
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}
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}
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}
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}
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