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https://github.com/bevyengine/bevy
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# Objective A big step in the migration to required components: meshes and materials! ## Solution As per the [selected proposal](https://hackmd.io/@bevy/required_components/%2Fj9-PnF-2QKK0on1KQ29UWQ): - Deprecate `MaterialMesh2dBundle`, `MaterialMeshBundle`, and `PbrBundle`. - Add `Mesh2d` and `Mesh3d` components, which wrap a `Handle<Mesh>`. - Add `MeshMaterial2d<M: Material2d>` and `MeshMaterial3d<M: Material>`, which wrap a `Handle<M>`. - Meshes *without* a mesh material should be rendered with a default material. The existence of a material is determined by `HasMaterial2d`/`HasMaterial3d`, which is required by `MeshMaterial2d`/`MeshMaterial3d`. This gets around problems with the generics. Previously: ```rust commands.spawn(MaterialMesh2dBundle { mesh: meshes.add(Circle::new(100.0)).into(), material: materials.add(Color::srgb(7.5, 0.0, 7.5)), transform: Transform::from_translation(Vec3::new(-200., 0., 0.)), ..default() }); ``` Now: ```rust commands.spawn(( Mesh2d(meshes.add(Circle::new(100.0))), MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))), Transform::from_translation(Vec3::new(-200., 0., 0.)), )); ``` If the mesh material is missing, previously nothing was rendered. Now, it renders a white default `ColorMaterial` in 2D and a `StandardMaterial` in 3D (this can be overridden). Below, only every other entity has a material:   Why white? This is still open for discussion, but I think white makes sense for a *default* material, while *invalid* asset handles pointing to nothing should have something like a pink material to indicate that something is broken (I don't handle that in this PR yet). This is kind of a mix of Godot and Unity: Godot just renders a white material for non-existent materials, while Unity renders nothing when no materials exist, but renders pink for invalid materials. I can also change the default material to pink if that is preferable though. ## Testing I ran some 2D and 3D examples to test if anything changed visually. I have not tested all examples or features yet however. If anyone wants to test more extensively, it would be appreciated! ## Implementation Notes - The relationship between `bevy_render` and `bevy_pbr` is weird here. `bevy_render` needs `Mesh3d` for its own systems, but `bevy_pbr` has all of the material logic, and `bevy_render` doesn't depend on it. I feel like the two crates should be refactored in some way, but I think that's out of scope for this PR. - I didn't migrate meshlets to required components yet. That can probably be done in a follow-up, as this is already a huge PR. - It is becoming increasingly clear to me that we really, *really* want to disallow raw asset handles as components. They caused me a *ton* of headache here already, and it took me a long time to find every place that queried for them or inserted them directly on entities, since there were no compiler errors for it. If we don't remove the `Component` derive, I expect raw asset handles to be a *huge* footgun for users as we transition to wrapper components, especially as handles as components have been the norm so far. I personally consider this to be a blocker for 0.15: we need to migrate to wrapper components for asset handles everywhere, and remove the `Component` derive. Also see https://github.com/bevyengine/bevy/issues/14124. --- ## Migration Guide Asset handles for meshes and mesh materials must now be wrapped in the `Mesh2d` and `MeshMaterial2d` or `Mesh3d` and `MeshMaterial3d` components for 2D and 3D respectively. Raw handles as components no longer render meshes. Additionally, `MaterialMesh2dBundle`, `MaterialMeshBundle`, and `PbrBundle` have been deprecated. Instead, use the mesh and material components directly. Previously: ```rust commands.spawn(MaterialMesh2dBundle { mesh: meshes.add(Circle::new(100.0)).into(), material: materials.add(Color::srgb(7.5, 0.0, 7.5)), transform: Transform::from_translation(Vec3::new(-200., 0., 0.)), ..default() }); ``` Now: ```rust commands.spawn(( Mesh2d(meshes.add(Circle::new(100.0))), MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))), Transform::from_translation(Vec3::new(-200., 0., 0.)), )); ``` If the mesh material is missing, a white default material is now used. Previously, nothing was rendered if the material was missing. The `WithMesh2d` and `WithMesh3d` query filter type aliases have also been removed. Simply use `With<Mesh2d>` or `With<Mesh3d>`. --------- Co-authored-by: Tim Blackbird <justthecooldude@gmail.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
91 lines
2.9 KiB
Rust
91 lines
2.9 KiB
Rust
//! A shader that uses the GLSL shading language.
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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 shader source files from the assets subdirectory
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const VERTEX_SHADER_ASSET_PATH: &str = "shaders/custom_material.vert";
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const FRAGMENT_SHADER_ASSET_PATH: &str = "shaders/custom_material.frag";
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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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asset_server: Res<AssetServer>,
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) {
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// cube
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commands.spawn((
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Mesh3d(meshes.add(Cuboid::default())),
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MeshMaterial3d(materials.add(CustomMaterial {
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color: LinearRgba::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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Transform::from_xyz(0.0, 0.5, 0.0),
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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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// This is the struct that will be passed to your shader
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#[derive(Asset, TypePath, AsBindGroup, Clone)]
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struct CustomMaterial {
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#[uniform(0)]
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color: LinearRgba,
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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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/// 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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VERTEX_SHADER_ASSET_PATH.into()
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}
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fn fragment_shader() -> ShaderRef {
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FRAGMENT_SHADER_ASSET_PATH.into()
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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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// 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: &MeshVertexBufferLayoutRef,
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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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