0a9c469d19
# Objective Fixes #7632. As discussed in #7634, it can be quite challenging for users to intuit the mental model of how states now work. ## Solution Rather than change the behavior of the `OnUpdate` system set, instead work on making sure it's easy to understand what's going on. Two things have been done: 1. Remove the `.on_update` method from our bevy of system building traits. This was special-cased and made states feel much more magical than they need to. 2. Improve the docs for the `OnUpdate` system set.
97 lines
3.1 KiB
Rust
97 lines
3.1 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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.add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest())) // prevents blurry sprites
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.add_state::<AppState>()
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.add_system_to_schedule(OnEnter(AppState::Setup), load_textures)
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.add_system(check_textures.in_set(OnUpdate(AppState::Setup)))
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.add_system_to_schedule(OnEnter(AppState::Finished), setup)
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.run();
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}
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#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash)]
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enum AppState {
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#[default]
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Setup,
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Finished,
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}
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impl States for AppState {
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type Iter = std::array::IntoIter<AppState, 2>;
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fn variants() -> Self::Iter {
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[AppState::Setup, AppState::Finished].into_iter()
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}
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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 next_state: ResMut<NextState<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 = asset_server
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.get_group_load_state(rpg_sprite_handles.handles.iter().map(|handle| handle.id()))
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{
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next_state.set(AppState::Finished);
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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 Some(texture) = textures.get(&handle) else {
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warn!("{:?} did not resolve to an `Image` asset.", asset_server.get_handle_path(handle));
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continue;
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};
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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(Camera2dBundle::default());
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// draw a sprite from the atlas
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commands.spawn(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(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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