a4640046fc
Adds a new `Handle<Storage>` asset type that can be used as a render asset, particularly for use with `AsBindGroup`. Closes: #13658 # Objective Allow users to create storage buffers in the main world without having to access the `RenderDevice`. While this resource is technically available, it's bad form to use in the main world and requires mixing rendering details with main world code. Additionally, this makes storage buffers easier to use with `AsBindGroup`, particularly in the following scenarios: - Sharing the same buffers between a compute stage and material shader. We already have examples of this for storage textures (see game of life example) and these changes allow a similar pattern to be used with storage buffers. - Preventing repeated gpu upload (see the previous easier to use `Vec` `AsBindGroup` option). - Allow initializing custom materials using `Default`. Previously, the lack of a `Default` implement for the raw `wgpu::Buffer` type made implementing a `AsBindGroup + Default` bound difficult in the presence of buffers. ## Solution Adds a new `Handle<Storage>` asset type that is prepared into a `GpuStorageBuffer` render asset. This asset can either be initialized with a `Vec<u8>` of properly aligned data or with a size hint. Users can modify the underlying `wgpu::BufferDescriptor` to provide additional usage flags. ## Migration Guide The `AsBindGroup` `storage` attribute has been modified to reference the new `Handle<Storage>` asset instead. Usages of Vec` should be converted into assets instead. --------- Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
114 lines
3.3 KiB
Rust
114 lines
3.3 KiB
Rust
//! This example demonstrates how to use a storage buffer with `AsBindGroup` in a custom material.
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use bevy::{
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prelude::*,
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reflect::TypePath,
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render::render_resource::{AsBindGroup, ShaderRef},
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};
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use bevy_render::render_asset::RenderAssetUsages;
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use bevy_render::storage::ShaderStorageBuffer;
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const SHADER_ASSET_PATH: &str = "shaders/storage_buffer.wgsl";
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fn main() {
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App::new()
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.add_plugins((DefaultPlugins, MaterialPlugin::<CustomMaterial>::default()))
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.add_systems(Startup, setup)
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.add_systems(Update, update)
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.run();
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}
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/// set up a simple 3D scene
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fn setup(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut buffers: ResMut<Assets<ShaderStorageBuffer>>,
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mut materials: ResMut<Assets<CustomMaterial>>,
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) {
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// Example data for the storage buffer
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let color_data: Vec<[f32; 4]> = vec![
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[1.0, 0.0, 0.0, 1.0],
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[0.0, 1.0, 0.0, 1.0],
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[0.0, 0.0, 1.0, 1.0],
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[1.0, 1.0, 0.0, 1.0],
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[0.0, 1.0, 1.0, 1.0],
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];
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let colors = buffers.add(ShaderStorageBuffer::new(
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bytemuck::cast_slice(color_data.as_slice()),
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RenderAssetUsages::default(),
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));
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// Create the custom material with the storage buffer
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let custom_material = CustomMaterial { colors };
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let material_handle = materials.add(custom_material);
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commands.insert_resource(CustomMaterialHandle(material_handle.clone()));
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// Spawn cubes with the custom material
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for i in -6..=6 {
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for j in -3..=3 {
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commands.spawn(MaterialMeshBundle {
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mesh: meshes.add(Cuboid::from_size(Vec3::splat(0.3))),
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material: material_handle.clone(),
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transform: Transform::from_xyz(i as f32, j as f32, 0.0),
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..default()
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});
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}
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}
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// Camera
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(0.0, 0.0, 10.0).looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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});
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}
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// Update the material color by time
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fn update(
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time: Res<Time>,
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material_handle: Res<CustomMaterialHandle>,
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mut materials: ResMut<Assets<CustomMaterial>>,
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mut buffers: ResMut<Assets<ShaderStorageBuffer>>,
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) {
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let material = materials.get_mut(&material_handle.0).unwrap();
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let buffer = buffers.get_mut(&material.colors).unwrap();
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buffer.data = Some(
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bytemuck::cast_slice(
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(0..5)
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.map(|i| {
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let t = time.elapsed_seconds() * 5.0;
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[
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(t + i as f32).sin() / 2.0 + 0.5,
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(t + i as f32 + 2.0).sin() / 2.0 + 0.5,
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(t + i as f32 + 4.0).sin() / 2.0 + 0.5,
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1.0,
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]
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})
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.collect::<Vec<[f32; 4]>>()
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.as_slice(),
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)
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.to_vec(),
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);
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}
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// Holds a handle to the custom material
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#[derive(Resource)]
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struct CustomMaterialHandle(Handle<CustomMaterial>);
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// This struct defines the data that will be passed to your shader
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#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
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struct CustomMaterial {
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#[storage(0, read_only)]
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colors: Handle<ShaderStorageBuffer>,
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}
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impl Material for CustomMaterial {
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fn vertex_shader() -> ShaderRef {
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SHADER_ASSET_PATH.into()
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}
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fn fragment_shader() -> ShaderRef {
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SHADER_ASSET_PATH.into()
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}
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}
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