bevy/examples/2d/texture_atlas.rs
Daniel McNab c893b99224 Optional .system (#2398)
This can be your 6 months post-christmas present.

# Objective

- Make `.system` optional
- yeet
- It's ugly
- Alternative title: `.system` is dead; long live `.system`
- **yeet**

## Solution

- Use a higher ranked lifetime, and some trait magic.

N.B. This PR does not actually remove any `.system`s, except in a couple of examples. Once this is merged we can do that piecemeal across crates, and decide on syntax for labels.
2021-06-27 00:40:09 +00:00

82 lines
2.9 KiB
Rust

use bevy::{asset::LoadState, prelude::*, sprite::TextureAtlasBuilder};
/// In this example we generate a new texture atlas (sprite sheet) from a folder containing
/// individual sprites
fn main() {
App::build()
.init_resource::<RpgSpriteHandles>()
.add_plugins(DefaultPlugins)
.add_state(AppState::Setup)
.add_system_set(SystemSet::on_enter(AppState::Setup).with_system(load_textures))
.add_system_set(SystemSet::on_update(AppState::Setup).with_system(check_textures))
.add_system_set(SystemSet::on_enter(AppState::Finished).with_system(setup))
.run();
}
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
enum AppState {
Setup,
Finished,
}
#[derive(Default)]
struct RpgSpriteHandles {
handles: Vec<HandleUntyped>,
}
fn load_textures(mut rpg_sprite_handles: ResMut<RpgSpriteHandles>, asset_server: Res<AssetServer>) {
rpg_sprite_handles.handles = asset_server.load_folder("textures/rpg").unwrap();
}
fn check_textures(
mut state: ResMut<State<AppState>>,
rpg_sprite_handles: ResMut<RpgSpriteHandles>,
asset_server: Res<AssetServer>,
) {
if let LoadState::Loaded =
asset_server.get_group_load_state(rpg_sprite_handles.handles.iter().map(|handle| handle.id))
{
state.set(AppState::Finished).unwrap();
}
}
fn setup(
mut commands: Commands,
rpg_sprite_handles: Res<RpgSpriteHandles>,
asset_server: Res<AssetServer>,
mut texture_atlases: ResMut<Assets<TextureAtlas>>,
mut textures: ResMut<Assets<Texture>>,
mut materials: ResMut<Assets<ColorMaterial>>,
) {
let mut texture_atlas_builder = TextureAtlasBuilder::default();
for handle in rpg_sprite_handles.handles.iter() {
let texture = textures.get(handle).unwrap();
texture_atlas_builder.add_texture(handle.clone_weak().typed::<Texture>(), texture);
}
let texture_atlas = texture_atlas_builder.finish(&mut textures).unwrap();
let texture_atlas_texture = texture_atlas.texture.clone();
let vendor_handle = asset_server.get_handle("textures/rpg/chars/vendor/generic-rpg-vendor.png");
let vendor_index = texture_atlas.get_texture_index(&vendor_handle).unwrap();
let atlas_handle = texture_atlases.add(texture_atlas);
// set up a scene to display our texture atlas
commands.spawn_bundle(OrthographicCameraBundle::new_2d());
// draw a sprite from the atlas
commands.spawn_bundle(SpriteSheetBundle {
transform: Transform {
translation: Vec3::new(150.0, 0.0, 0.0),
scale: Vec3::splat(4.0),
..Default::default()
},
sprite: TextureAtlasSprite::new(vendor_index as u32),
texture_atlas: atlas_handle,
..Default::default()
});
// draw the atlas itself
commands.spawn_bundle(SpriteBundle {
material: materials.add(texture_atlas_texture.into()),
transform: Transform::from_xyz(-300.0, 0.0, 0.0),
..Default::default()
});
}