translation/
translation.rs

1//! Illustrates how to move an object along an axis.
2
3use bevy::prelude::*;
4
5// Define a struct to keep some information about our entity.
6// Here it's an arbitrary movement speed, the spawn location, and a maximum distance from it.
7#[derive(Component)]
8struct Movable {
9    spawn: Vec3,
10    max_distance: f32,
11    speed: f32,
12}
13
14// Implement a utility function for easier Movable struct creation.
15impl Movable {
16    fn new(spawn: Vec3) -> Self {
17        Movable {
18            spawn,
19            max_distance: 5.0,
20            speed: 2.0,
21        }
22    }
23}
24
25fn main() {
26    App::new()
27        .add_plugins(DefaultPlugins)
28        .add_systems(Startup, setup)
29        .add_systems(Update, move_cube)
30        .run();
31}
32
33// Startup system to setup the scene and spawn all relevant entities.
34fn setup(
35    mut commands: Commands,
36    mut meshes: ResMut<Assets<Mesh>>,
37    mut materials: ResMut<Assets<StandardMaterial>>,
38) {
39    // Add a cube to visualize translation.
40    let entity_spawn = Vec3::ZERO;
41    commands.spawn((
42        Mesh3d(meshes.add(Cuboid::default())),
43        MeshMaterial3d(materials.add(Color::WHITE)),
44        Transform::from_translation(entity_spawn),
45        Movable::new(entity_spawn),
46    ));
47
48    // Spawn a camera looking at the entities to show what's happening in this example.
49    commands.spawn((
50        Camera3d::default(),
51        Transform::from_xyz(0.0, 10.0, 20.0).looking_at(entity_spawn, Vec3::Y),
52    ));
53
54    // Add a light source for better 3d visibility.
55    commands.spawn((
56        DirectionalLight::default(),
57        Transform::from_xyz(3.0, 3.0, 3.0).looking_at(Vec3::ZERO, Vec3::Y),
58    ));
59}
60
61// This system will move all Movable entities with a Transform
62fn move_cube(mut cubes: Query<(&mut Transform, &mut Movable)>, timer: Res<Time>) {
63    for (mut transform, mut cube) in &mut cubes {
64        // Check if the entity moved too far from its spawn, if so invert the moving direction.
65        if (cube.spawn - transform.translation).length() > cube.max_distance {
66            cube.speed *= -1.0;
67        }
68        let direction = transform.local_x();
69        transform.translation += direction * cube.speed * timer.delta_secs();
70    }
71}
translation/translation.rs

translation/
translation.rs
