 1efc762924
			
		
	
	
		1efc762924
		
			
		
	
	
	
	
		
			
			# Objective
- Introduce a stable alternative to
[`std::any::type_name`](https://doc.rust-lang.org/std/any/fn.type_name.html).
- Rewrite of #5805 with heavy inspiration in design.
- On the path to #5830.
- Part of solving #3327.
## Solution
- Add a `TypePath` trait for static stable type path/name information.
- Add a `TypePath` derive macro.
- Add a `impl_type_path` macro for implementing internal and foreign
types in `bevy_reflect`.
---
## Changelog
- Added `TypePath` trait.
- Added `DynamicTypePath` trait and `get_type_path` method to `Reflect`.
- Added a `TypePath` derive macro.
- Added a `bevy_reflect::impl_type_path` for implementing `TypePath` on
internal and foreign types in `bevy_reflect`.
- Changed `bevy_reflect::utility::(Non)GenericTypeInfoCell` to
`(Non)GenericTypedCell<T>` which allows us to be generic over both
`TypeInfo` and `TypePath`.
- `TypePath` is now a supertrait of `Asset`, `Material` and
`Material2d`.
- `impl_reflect_struct` needs a `#[type_path = "..."]` attribute to be
specified.
- `impl_reflect_value` needs to either specify path starting with a
double colon (`::core::option::Option`) or an `in my_crate::foo`
declaration.
- Added `bevy_reflect_derive::ReflectTypePath`.
- Most uses of `Ident` in `bevy_reflect_derive` changed to use
`ReflectTypePath`.
## Migration Guide
- Implementors of `Asset`, `Material` and `Material2d` now also need to
derive `TypePath`.
- Manual implementors of `Reflect` will need to implement the new
`get_type_path` method.
## Open Questions
- [x] ~This PR currently does not migrate any usages of
`std::any::type_name` to use `bevy_reflect::TypePath` to ease the review
process. Should it?~ Migration will be left to a follow-up PR.
- [ ] This PR adds a lot of `#[derive(TypePath)]` and `T: TypePath` to
satisfy new bounds, mostly when deriving `TypeUuid`. Should we make
`TypePath` a supertrait of `TypeUuid`? [Should we remove `TypeUuid` in
favour of
`TypePath`?](2afbd85532 (r961067892))
		
	
			
		
			
				
	
	
		
			91 lines
		
	
	
		
			2.8 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			91 lines
		
	
	
		
			2.8 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
| //! A shader that uses the GLSL shading language.
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| 
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| use bevy::{
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|     pbr::{MaterialPipeline, MaterialPipelineKey},
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|     prelude::*,
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|     reflect::{TypePath, TypeUuid},
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|     render::{
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|         mesh::MeshVertexBufferLayout,
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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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| 
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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(MaterialPlugin::<CustomMaterial>::default())
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|         .add_systems(Startup, setup)
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|         .run();
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| }
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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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|     asset_server: Res<AssetServer>,
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| ) {
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|     // cube
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|     commands.spawn(MaterialMeshBundle {
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|         mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
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|         transform: Transform::from_xyz(0.0, 0.5, 0.0),
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|         material: materials.add(CustomMaterial {
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|             color: Color::BLUE,
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|             color_texture: Some(asset_server.load("branding/icon.png")),
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|             alpha_mode: AlphaMode::Blend,
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|         }),
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|         ..default()
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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(-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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| 
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| // This is the struct that will be passed to your shader
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| #[derive(AsBindGroup, Clone, TypeUuid, TypePath)]
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| #[uuid = "4ee9c363-1124-4113-890e-199d81b00281"]
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| pub struct CustomMaterial {
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|     #[uniform(0)]
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|     color: Color,
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|     #[texture(1)]
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|     #[sampler(2)]
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|     color_texture: Option<Handle<Image>>,
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|     alpha_mode: AlphaMode,
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| }
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| 
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| /// The Material trait is very configurable, but comes with sensible defaults for all methods.
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| /// You only need to implement functions for features that need non-default behavior. See the Material api docs for details!
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| /// When using the GLSL shading language for your shader, the specialize method must be overridden.
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| impl Material for CustomMaterial {
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|     fn vertex_shader() -> ShaderRef {
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|         "shaders/custom_material.vert".into()
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|     }
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| 
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|     fn fragment_shader() -> ShaderRef {
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|         "shaders/custom_material.frag".into()
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|     }
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| 
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|     fn alpha_mode(&self) -> AlphaMode {
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|         self.alpha_mode
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|     }
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| 
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|     // Bevy assumes by default that vertex shaders use the "vertex" entry point
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|     // and fragment shaders use the "fragment" entry point (for WGSL shaders).
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|     // GLSL uses "main" as the entry point, so we must override the defaults here
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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: &MeshVertexBufferLayout,
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|         _key: MaterialPipelineKey<Self>,
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|     ) -> Result<(), SpecializedMeshPipelineError> {
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|         descriptor.vertex.entry_point = "main".into();
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|         descriptor.fragment.as_mut().unwrap().entry_point = "main".into();
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|         Ok(())
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|     }
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| }
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