435d9bc02c
The examples won't work when copy-pasted to another project, without also copying their shader files. This change adds constants at the top of the files to bring attention to the dependencies. Follow up to [#13624](https://github.com/bevyengine/bevy/pull/13624#issuecomment-2143872791)
104 lines
3.0 KiB
Rust
104 lines
3.0 KiB
Rust
//! A shader that uses "shaders defs", which selectively toggle parts of a shader.
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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::MeshVertexBufferLayoutRef,
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render_resource::{
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AsBindGroup, RenderPipelineDescriptor, ShaderRef, SpecializedMeshPipelineError,
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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/shader_defs.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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/// 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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// blue cube
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commands.spawn(MaterialMeshBundle {
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mesh: meshes.add(Cuboid::default()),
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transform: Transform::from_xyz(-1.0, 0.5, 0.0),
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material: materials.add(CustomMaterial {
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color: LinearRgba::BLUE,
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is_red: false,
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}),
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..default()
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});
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// red cube (with green color overridden by the IS_RED "shader def")
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commands.spawn(MaterialMeshBundle {
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mesh: meshes.add(Cuboid::default()),
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transform: Transform::from_xyz(1.0, 0.5, 0.0),
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material: materials.add(CustomMaterial {
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color: LinearRgba::GREEN,
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is_red: true,
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}),
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..default()
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});
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// camera
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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});
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}
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impl Material for CustomMaterial {
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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<Self>,
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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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if key.bind_group_data.is_red {
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let fragment = descriptor.fragment.as_mut().unwrap();
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fragment.shader_defs.push("IS_RED".into());
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}
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Ok(())
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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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#[bind_group_data(CustomMaterialKey)]
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struct CustomMaterial {
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#[uniform(0)]
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color: LinearRgba,
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is_red: bool,
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}
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// This key is used to identify a specific permutation of this material pipeline.
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// In this case, we specialize on whether or not to configure the "IS_RED" shader def.
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// Specialization keys should be kept as small / cheap to hash as possible,
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// as they will be used to look up the pipeline for each drawn entity with this material type.
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#[derive(Eq, PartialEq, Hash, Clone)]
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struct CustomMaterialKey {
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is_red: bool,
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}
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impl From<&CustomMaterial> for CustomMaterialKey {
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fn from(material: &CustomMaterial) -> Self {
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Self {
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is_red: material.is_red,
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}
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}
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}
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