mirror of
https://github.com/bevyengine/bevy
synced 2024-12-21 02:23:08 +00:00
93fc2d12cf
# Objective
The type `AssetLoadError` has `PartialEq` and `Eq` impls, which is
problematic due to the fact that the `AssetLoaderError` and
`AddAsyncError` variants lie in their impls: they will return `true` for
any `Box<dyn Error>` with the same `TypeId`, even if the actual value is
different. This can lead to subtle bugs if a user relies on the equality
comparison to ensure that two values are equal.
The same is true for `DependencyLoadState`,
`RecursiveDependencyLoadState`.
More generally, it is an anti-pattern for large error types involving
dynamic dispatch, such as `AssetLoadError`, to have equality
comparisons. Directly comparing two errors for equality is usually not
desired -- if some logic needs to branch based on the value of an error,
it is usually more correct to check for specific variants and inspect
their fields.
As far as I can tell, the only reason these errors have equality
comparisons is because the `LoadState` enum wraps `AssetLoadError` for
its `Failed` variant. This equality comparison is only used to check for
`== LoadState::Loaded`, which we can easily replace with an `is_loaded`
method.
## Solution
Remove the `{Partial}Eq` impls from `LoadState`, which also allows us to
remove it from the error types.
## Migration Guide
The types `bevy_asset::AssetLoadError` and `bevy_asset::LoadState` no
longer support equality comparisons. If you need to check for an asset's
load state, consider checking for a specific variant using
`LoadState::is_loaded` or the `matches!` macro. Similarly, consider
using the `matches!` macro to check for specific variants of the
`AssetLoadError` type if you need to inspect the value of an asset load
error in your code.
`DependencyLoadState` and `RecursiveDependencyLoadState` are not
released yet, so no migration needed,
---------
Co-authored-by: Joseph <21144246+JoJoJet@users.noreply.github.com>
97 lines
2.7 KiB
Rust
97 lines
2.7 KiB
Rust
//! This example illustrates how to create a texture for use with a `texture_2d_array<f32>` shader
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//! uniform variable.
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use bevy::{
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prelude::*,
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reflect::TypePath,
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render::render_resource::{AsBindGroup, ShaderRef},
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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/array_texture.wgsl";
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fn main() {
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App::new()
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.add_plugins((
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DefaultPlugins,
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MaterialPlugin::<ArrayTextureMaterial>::default(),
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))
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.add_systems(Startup, setup)
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.add_systems(Update, create_array_texture)
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.run();
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}
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#[derive(Resource)]
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struct LoadingTexture {
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is_loaded: bool,
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handle: Handle<Image>,
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}
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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// Start loading the texture.
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commands.insert_resource(LoadingTexture {
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is_loaded: false,
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handle: asset_server.load("textures/array_texture.png"),
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});
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// light
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commands.spawn((
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DirectionalLight::default(),
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Transform::from_xyz(3.0, 2.0, 1.0).looking_at(Vec3::ZERO, Vec3::Y),
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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(5.0, 5.0, 5.0).looking_at(Vec3::new(1.5, 0.0, 0.0), Vec3::Y),
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));
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}
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fn create_array_texture(
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mut commands: Commands,
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asset_server: Res<AssetServer>,
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mut loading_texture: ResMut<LoadingTexture>,
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mut images: ResMut<Assets<Image>>,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<ArrayTextureMaterial>>,
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) {
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if loading_texture.is_loaded
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|| !asset_server
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.load_state(loading_texture.handle.id())
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.is_loaded()
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{
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return;
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}
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loading_texture.is_loaded = true;
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let image = images.get_mut(&loading_texture.handle).unwrap();
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// Create a new array texture asset from the loaded texture.
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let array_layers = 4;
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image.reinterpret_stacked_2d_as_array(array_layers);
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// Spawn some cubes using the array texture
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let mesh_handle = meshes.add(Cuboid::default());
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let material_handle = materials.add(ArrayTextureMaterial {
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array_texture: loading_texture.handle.clone(),
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});
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for x in -5..=5 {
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commands.spawn((
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Mesh3d(mesh_handle.clone()),
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MeshMaterial3d(material_handle.clone()),
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Transform::from_xyz(x as f32 + 0.5, 0.0, 0.0),
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));
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}
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}
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#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
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struct ArrayTextureMaterial {
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#[texture(0, dimension = "2d_array")]
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#[sampler(1)]
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array_texture: Handle<Image>,
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}
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impl Material for ArrayTextureMaterial {
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fn fragment_shader() -> ShaderRef {
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SHADER_ASSET_PATH.into()
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}
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}
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