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*This PR description is an edited copy of #5007, written by @alice-i-cecile.* # Objective Follow-up to https://github.com/bevyengine/bevy/pull/2254. The `Resource` trait currently has a blanket implementation for all types that meet its bounds. While ergonomic, this results in several drawbacks: * it is possible to make confusing, silent mistakes such as inserting a function pointer (Foo) rather than a value (Foo::Bar) as a resource * it is challenging to discover if a type is intended to be used as a resource * we cannot later add customization options (see the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/27-derive-component.md) for the equivalent choice for Component). * dependencies can use the same Rust type as a resource in invisibly conflicting ways * raw Rust types used as resources cannot preserve privacy appropriately, as anyone able to access that type can read and write to internal values * we cannot capture a definitive list of possible resources to display to users in an editor ## Notes to reviewers * Review this commit-by-commit; there's effectively no back-tracking and there's a lot of churn in some of these commits. *ira: My commits are not as well organized :')* * I've relaxed the bound on Local to Send + Sync + 'static: I don't think these concerns apply there, so this can keep things simple. Storing e.g. a u32 in a Local is fine, because there's a variable name attached explaining what it does. * I think this is a bad place for the Resource trait to live, but I've left it in place to make reviewing easier. IMO that's best tackled with https://github.com/bevyengine/bevy/issues/4981. ## Changelog `Resource` is no longer automatically implemented for all matching types. Instead, use the new `#[derive(Resource)]` macro. ## Migration Guide Add `#[derive(Resource)]` to all types you are using as a resource. If you are using a third party type as a resource, wrap it in a tuple struct to bypass orphan rules. Consider deriving `Deref` and `DerefMut` to improve ergonomics. `ClearColor` no longer implements `Component`. Using `ClearColor` as a component in 0.8 did nothing. Use the `ClearColorConfig` in the `Camera3d` and `Camera2d` components instead. Co-authored-by: Alice <alice.i.cecile@gmail.com> Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: devil-ira <justthecooldude@gmail.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
67 lines
1.7 KiB
Rust
67 lines
1.7 KiB
Rust
//! Implements loader for a custom asset type.
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use bevy::{
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asset::{AssetLoader, LoadContext, LoadedAsset},
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prelude::*,
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reflect::TypeUuid,
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utils::BoxedFuture,
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};
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use serde::Deserialize;
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#[derive(Debug, Deserialize, TypeUuid)]
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#[uuid = "39cadc56-aa9c-4543-8640-a018b74b5052"]
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pub struct CustomAsset {
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pub value: i32,
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}
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#[derive(Default)]
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pub struct CustomAssetLoader;
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impl AssetLoader for CustomAssetLoader {
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fn load<'a>(
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&'a self,
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bytes: &'a [u8],
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load_context: &'a mut LoadContext,
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) -> BoxedFuture<'a, Result<(), bevy::asset::Error>> {
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Box::pin(async move {
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let custom_asset = ron::de::from_bytes::<CustomAsset>(bytes)?;
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load_context.set_default_asset(LoadedAsset::new(custom_asset));
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Ok(())
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})
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}
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fn extensions(&self) -> &[&str] {
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&["custom"]
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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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.init_resource::<State>()
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.add_asset::<CustomAsset>()
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.init_asset_loader::<CustomAssetLoader>()
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.add_startup_system(setup)
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.add_system(print_on_load)
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.run();
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}
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#[derive(Resource, Default)]
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struct State {
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handle: Handle<CustomAsset>,
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printed: bool,
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}
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fn setup(mut state: ResMut<State>, asset_server: Res<AssetServer>) {
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state.handle = asset_server.load("data/asset.custom");
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}
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fn print_on_load(mut state: ResMut<State>, custom_assets: ResMut<Assets<CustomAsset>>) {
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let custom_asset = custom_assets.get(&state.handle);
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if state.printed || custom_asset.is_none() {
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return;
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}
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info!("Custom asset loaded: {:?}", custom_asset.unwrap());
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state.printed = true;
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}
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