bevy/examples/ecs/hierarchy.rs
Emerson Coskey 7d40e3ec87
Migrate bevy_sprite to required components (#15489)
# Objective

Continue migration of bevy APIs to required components, following
guidance of https://hackmd.io/@bevy/required_components/

## Solution

- Make `Sprite` require `Transform` and `Visibility` and
`SyncToRenderWorld`
- move image and texture atlas handles into `Sprite`
- deprecate `SpriteBundle`
- remove engine uses of `SpriteBundle`

## Testing

ran cargo tests on bevy_sprite and tested several sprite examples.

---

## Migration Guide

Replace all uses of `SpriteBundle` with `Sprite`. There are several new
convenience constructors: `Sprite::from_image`,
`Sprite::from_atlas_image`, `Sprite::from_color`.

WARNING: use of `Handle<Image>` and `TextureAtlas` as components on
sprite entities will NO LONGER WORK. Use the fields on `Sprite` instead.
I would have removed the `Component` impls from `TextureAtlas` and
`Handle<Image>` except it is still used within ui. We should fix this
moving forward with the migration.
2024-10-09 16:17:26 +00:00

89 lines
3 KiB
Rust

//! Creates a hierarchy of parents and children entities.
use std::f32::consts::*;
use bevy::{color::palettes::css::*, prelude::*};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(Update, rotate)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
commands.spawn(Camera2d);
let texture = asset_server.load("branding/icon.png");
// Spawn a root entity with no parent
let parent = commands
.spawn((
Sprite::from_image(texture.clone()),
Transform::from_scale(Vec3::splat(0.75)),
))
// With that entity as a parent, run a lambda that spawns its children
.with_children(|parent| {
// parent is a ChildBuilder, which has a similar API to Commands
parent.spawn((
Transform::from_xyz(250.0, 0.0, 0.0).with_scale(Vec3::splat(0.75)),
Sprite {
image: texture.clone(),
color: BLUE.into(),
..default()
},
));
})
// Store parent entity for next sections
.id();
// Another way is to use the add_child function to add children after the parent
// entity has already been spawned.
let child = commands
.spawn((
Sprite {
image: texture,
color: LIME.into(),
..default()
},
Transform::from_xyz(0.0, 250.0, 0.0).with_scale(Vec3::splat(0.75)),
))
.id();
// Add child to the parent.
commands.entity(parent).add_child(child);
}
// A simple system to rotate the root entity, and rotate all its children separately
fn rotate(
mut commands: Commands,
time: Res<Time>,
mut parents_query: Query<(Entity, &Children), With<Sprite>>,
mut transform_query: Query<&mut Transform, With<Sprite>>,
) {
for (parent, children) in &mut parents_query {
if let Ok(mut transform) = transform_query.get_mut(parent) {
transform.rotate_z(-PI / 2. * time.delta_seconds());
}
// To iterate through the entities children, just treat the Children component as a Vec
// Alternatively, you could query entities that have a Parent component
for child in children {
if let Ok(mut transform) = transform_query.get_mut(*child) {
transform.rotate_z(PI * time.delta_seconds());
}
}
// To demonstrate removing children, we'll remove a child after a couple of seconds.
if time.elapsed_seconds() >= 2.0 && children.len() == 2 {
let child = children.last().unwrap();
commands.entity(*child).despawn_recursive();
}
if time.elapsed_seconds() >= 4.0 {
// This will remove the entity from its parent's list of children, as well as despawn
// any children the entity has.
commands.entity(parent).despawn_recursive();
}
}
}