bevy/examples/2d/sprite_sheet.rs
Carter Anderson dcc03724a5 Base Sets (#7466)
# Objective

NOTE: This depends on #7267 and should not be merged until #7267 is merged. If you are reviewing this before that is merged, I highly recommend viewing the Base Sets commit instead of trying to find my changes amongst those from #7267.

"Default sets" as described by the [Stageless RFC](https://github.com/bevyengine/rfcs/pull/45) have some [unfortunate consequences](https://github.com/bevyengine/bevy/discussions/7365).

## Solution

This adds "base sets" as a variant of `SystemSet`:

A set is a "base set" if `SystemSet::is_base` returns `true`. Typically this will be opted-in to using the `SystemSet` derive:

```rust
#[derive(SystemSet, Clone, Hash, Debug, PartialEq, Eq)]
#[system_set(base)]
enum MyBaseSet {
  A,
  B,
}
``` 

**Base sets are exclusive**: a system can belong to at most one "base set". Adding a system to more than one will result in an error. When possible we fail immediately during system-config-time with a nice file + line number. For the more nested graph-ey cases, this will fail at the final schedule build. 

**Base sets cannot belong to other sets**: this is where the word "base" comes from

Systems and Sets can only be added to base sets using `in_base_set`. Calling `in_set` with a base set will fail. As will calling `in_base_set` with a normal set.

```rust
app.add_system(foo.in_base_set(MyBaseSet::A))
       // X must be a normal set ... base sets cannot be added to base sets
       .configure_set(X.in_base_set(MyBaseSet::A))
```

Base sets can still be configured like normal sets:

```rust
app.add_system(MyBaseSet::B.after(MyBaseSet::Ap))
``` 

The primary use case for base sets is enabling a "default base set":

```rust
schedule.set_default_base_set(CoreSet::Update)
  // this will belong to CoreSet::Update by default
  .add_system(foo)
  // this will override the default base set with PostUpdate
  .add_system(bar.in_base_set(CoreSet::PostUpdate))
```

This allows us to build apis that work by default in the standard Bevy style. This is a rough analog to the "default stage" model, but it use the new "stageless sets" model instead, with all of the ordering flexibility (including exclusive systems) that it provides.

---

## Changelog

- Added "base sets" and ported CoreSet to use them.

## Migration Guide

TODO
2023-02-06 03:10:08 +00:00

65 lines
2 KiB
Rust

//! Renders an animated sprite by loading all animation frames from a single image (a sprite sheet)
//! into a texture atlas, and changing the displayed image periodically.
use bevy::prelude::*;
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest())) // prevents blurry sprites
.add_startup_system(setup)
.add_system(animate_sprite)
.run();
}
#[derive(Component)]
struct AnimationIndices {
first: usize,
last: usize,
}
#[derive(Component, Deref, DerefMut)]
struct AnimationTimer(Timer);
fn animate_sprite(
time: Res<Time>,
mut query: Query<(
&AnimationIndices,
&mut AnimationTimer,
&mut TextureAtlasSprite,
)>,
) {
for (indices, mut timer, mut sprite) in &mut query {
timer.tick(time.delta());
if timer.just_finished() {
sprite.index = if sprite.index == indices.last {
indices.first
} else {
sprite.index + 1
};
}
}
}
fn setup(
mut commands: Commands,
asset_server: Res<AssetServer>,
mut texture_atlases: ResMut<Assets<TextureAtlas>>,
) {
let texture_handle = asset_server.load("textures/rpg/chars/gabe/gabe-idle-run.png");
let texture_atlas =
TextureAtlas::from_grid(texture_handle, Vec2::new(24.0, 24.0), 7, 1, None, None);
let texture_atlas_handle = texture_atlases.add(texture_atlas);
// Use only the subset of sprites in the sheet that make up the run animation
let animation_indices = AnimationIndices { first: 1, last: 6 };
commands.spawn(Camera2dBundle::default());
commands.spawn((
SpriteSheetBundle {
texture_atlas: texture_atlas_handle,
sprite: TextureAtlasSprite::new(animation_indices.first),
transform: Transform::from_scale(Vec3::splat(6.0)),
..default()
},
animation_indices,
AnimationTimer(Timer::from_seconds(0.1, TimerMode::Repeating)),
));
}