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custom_vertex_attribute.rs
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custom_vertex_attribute.rs
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//! A shader that reads a mesh's custom vertex attribute.
use bevy::{
pbr::{MaterialPipeline, MaterialPipelineKey},
prelude::*,
reflect::TypePath,
render::{
mesh::{MeshVertexAttribute, MeshVertexBufferLayout},
render_resource::{
AsBindGroup, RenderPipelineDescriptor, ShaderRef, SpecializedMeshPipelineError,
VertexFormat,
},
},
};
fn main() {
App::new()
.add_plugins((DefaultPlugins, MaterialPlugin::<CustomMaterial>::default()))
.add_systems(Startup, setup)
.run();
}
// A "high" random id should be used for custom attributes to ensure consistent sorting and avoid collisions with other attributes.
// See the MeshVertexAttribute docs for more info.
const ATTRIBUTE_BLEND_COLOR: MeshVertexAttribute =
MeshVertexAttribute::new("BlendColor", 988540917, VertexFormat::Float32x4);
/// set up a simple 3D scene
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<CustomMaterial>>,
) {
let mesh = Mesh::from(Cuboid::default())
// Sets the custom attribute
.with_inserted_attribute(
ATTRIBUTE_BLEND_COLOR,
// The cube mesh has 24 vertices (6 faces, 4 vertices per face), so we insert one BlendColor for each
vec![[1.0, 0.0, 0.0, 1.0]; 24],
);
// cube
commands.spawn(MaterialMeshBundle {
mesh: meshes.add(mesh),
transform: Transform::from_xyz(0.0, 0.5, 0.0),
material: materials.add(CustomMaterial {
color: Color::WHITE,
}),
..default()
});
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
}
// This is the struct that will be passed to your shader
#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
struct CustomMaterial {
#[uniform(0)]
color: Color,
}
impl Material for CustomMaterial {
fn vertex_shader() -> ShaderRef {
"shaders/custom_vertex_attribute.wgsl".into()
}
fn fragment_shader() -> ShaderRef {
"shaders/custom_vertex_attribute.wgsl".into()
}
fn specialize(
_pipeline: &MaterialPipeline<Self>,
descriptor: &mut RenderPipelineDescriptor,
layout: &MeshVertexBufferLayout,
_key: MaterialPipelineKey<Self>,
) -> Result<(), SpecializedMeshPipelineError> {
let vertex_layout = layout.get_layout(&[
Mesh::ATTRIBUTE_POSITION.at_shader_location(0),
ATTRIBUTE_BLEND_COLOR.at_shader_location(1),
])?;
descriptor.vertex.buffers = vec![vertex_layout];
Ok(())
}
}