e6ba9a6d18
# Objective Closes #18075 In order to enable a number of patterns for dynamic materials in the engine, it's necessary to decouple the renderer from the `Material` trait. This opens the possibility for: - Materials that aren't coupled to `AsBindGroup`. - 2d using the underlying 3d bindless infrastructure. - Dynamic materials that can change their layout at runtime. - Materials that aren't even backed by a Rust struct at all. ## Solution In short, remove all trait bounds from render world material systems and resources. This means moving a bunch of stuff onto `MaterialProperties` and engaging in some hacks to make specialization work. Rather than storing the bind group data in `MaterialBindGroupAllocator`, right now we're storing it in a closure on `MaterialProperties`. TBD if this has bad performance characteristics. ## Benchmarks - `many_cubes`: `cargo run --example many_cubes --release --features=bevy/trace_tracy -- --vary-material-data-per-instance`:  - @DGriffin91's Caldera `cargo run --release --features=bevy/trace_tracy -- --random-materials`  - @DGriffin91's Caldera with 20 unique material types (i.e. `MaterialPlugin<M>`) and random materials per mesh `cargo run --release --features=bevy/trace_tracy -- --random-materials`  ### TODO - We almost certainly lost some parallelization from removing the type params that could be gained back from smarter iteration. - Test all the things that could have broken. - ~Fix meshlets~ ## Showcase See [the example](https://github.com/bevyengine/bevy/pull/19667/files#diff-9d768cfe1c3aa81eff365d250d3cbe5a63e8df63e81dd85f64c3c3cd993f6d94) for a custom material implemented without the use of the `Material` trait and thus `AsBindGroup`.  --------- Co-authored-by: IceSentry <IceSentry@users.noreply.github.com> Co-authored-by: IceSentry <c.giguere42@gmail.com>
90 lines
2.7 KiB
Rust
90 lines
2.7 KiB
Rust
//! A shader that reads a mesh's custom vertex attribute.
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use bevy::{
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pbr::{MaterialPipeline, MaterialPipelineKey},
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prelude::*,
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reflect::TypePath,
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render::{
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mesh::{MeshVertexAttribute, MeshVertexBufferLayoutRef},
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render_resource::{
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AsBindGroup, RenderPipelineDescriptor, ShaderRef, SpecializedMeshPipelineError,
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VertexFormat,
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},
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},
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};
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/// This example uses a shader source file from the assets subdirectory
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const SHADER_ASSET_PATH: &str = "shaders/custom_vertex_attribute.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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.run();
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}
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// A "high" random id should be used for custom attributes to ensure consistent sorting and avoid collisions with other attributes.
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// See the MeshVertexAttribute docs for more info.
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const ATTRIBUTE_BLEND_COLOR: MeshVertexAttribute =
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MeshVertexAttribute::new("BlendColor", 988540917, VertexFormat::Float32x4);
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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 materials: ResMut<Assets<CustomMaterial>>,
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) {
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let mesh = Mesh::from(Cuboid::default())
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// Sets the custom attribute
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.with_inserted_attribute(
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ATTRIBUTE_BLEND_COLOR,
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// The cube mesh has 24 vertices (6 faces, 4 vertices per face), so we insert one BlendColor for each
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vec![[1.0, 0.0, 0.0, 1.0]; 24],
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);
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// cube
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commands.spawn((
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Mesh3d(meshes.add(mesh)),
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MeshMaterial3d(materials.add(CustomMaterial {
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color: LinearRgba::WHITE,
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})),
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Transform::from_xyz(0.0, 0.5, 0.0),
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));
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// camera
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commands.spawn((
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Camera3d::default(),
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Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
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));
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}
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// This is the struct 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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#[uniform(0)]
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color: LinearRgba,
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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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fn specialize(
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_pipeline: &MaterialPipeline,
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descriptor: &mut RenderPipelineDescriptor,
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layout: &MeshVertexBufferLayoutRef,
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_key: MaterialPipelineKey<Self>,
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) -> Result<(), SpecializedMeshPipelineError> {
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let vertex_layout = layout.0.get_layout(&[
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Mesh::ATTRIBUTE_POSITION.at_shader_location(0),
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ATTRIBUTE_BLEND_COLOR.at_shader_location(1),
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])?;
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descriptor.vertex.buffers = vec![vertex_layout];
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Ok(())
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}
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}
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