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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>
84 lines
3 KiB
Rust
84 lines
3 KiB
Rust
//! In this example we generate a new texture atlas (sprite sheet) from a folder containing
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//! individual sprites.
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use bevy::{asset::LoadState, prelude::*};
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fn main() {
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App::new()
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.init_resource::<RpgSpriteHandles>()
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.insert_resource(ImageSettings::default_nearest()) // prevents blurry sprites
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.add_plugins(DefaultPlugins)
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.add_state(AppState::Setup)
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.add_system_set(SystemSet::on_enter(AppState::Setup).with_system(load_textures))
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.add_system_set(SystemSet::on_update(AppState::Setup).with_system(check_textures))
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.add_system_set(SystemSet::on_enter(AppState::Finished).with_system(setup))
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.run();
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}
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#[derive(Debug, Clone, PartialEq, Eq, Hash)]
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enum AppState {
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Setup,
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Finished,
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}
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#[derive(Resource, Default)]
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struct RpgSpriteHandles {
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handles: Vec<HandleUntyped>,
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}
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fn load_textures(mut rpg_sprite_handles: ResMut<RpgSpriteHandles>, asset_server: Res<AssetServer>) {
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rpg_sprite_handles.handles = asset_server.load_folder("textures/rpg").unwrap();
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}
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fn check_textures(
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mut state: ResMut<State<AppState>>,
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rpg_sprite_handles: ResMut<RpgSpriteHandles>,
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asset_server: Res<AssetServer>,
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) {
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if let LoadState::Loaded =
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asset_server.get_group_load_state(rpg_sprite_handles.handles.iter().map(|handle| handle.id))
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{
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state.set(AppState::Finished).unwrap();
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}
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}
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fn setup(
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mut commands: Commands,
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rpg_sprite_handles: Res<RpgSpriteHandles>,
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asset_server: Res<AssetServer>,
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mut texture_atlases: ResMut<Assets<TextureAtlas>>,
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mut textures: ResMut<Assets<Image>>,
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) {
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let mut texture_atlas_builder = TextureAtlasBuilder::default();
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for handle in &rpg_sprite_handles.handles {
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let handle = handle.typed_weak();
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let texture = textures.get(&handle).expect("Textures folder contained a file which way matched by a loader which did not create an `Image` asset");
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texture_atlas_builder.add_texture(handle, texture);
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}
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let texture_atlas = texture_atlas_builder.finish(&mut textures).unwrap();
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let texture_atlas_texture = texture_atlas.texture.clone();
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let vendor_handle = asset_server.get_handle("textures/rpg/chars/vendor/generic-rpg-vendor.png");
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let vendor_index = texture_atlas.get_texture_index(&vendor_handle).unwrap();
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let atlas_handle = texture_atlases.add(texture_atlas);
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// set up a scene to display our texture atlas
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commands.spawn_bundle(Camera2dBundle::default());
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// draw a sprite from the atlas
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commands.spawn_bundle(SpriteSheetBundle {
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transform: Transform {
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translation: Vec3::new(150.0, 0.0, 0.0),
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scale: Vec3::splat(4.0),
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..default()
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},
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sprite: TextureAtlasSprite::new(vendor_index),
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texture_atlas: atlas_handle,
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..default()
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});
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// draw the atlas itself
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commands.spawn_bundle(SpriteBundle {
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texture: texture_atlas_texture,
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transform: Transform::from_xyz(-300.0, 0.0, 0.0),
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..default()
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});
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}
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