simple_picking/
simple_picking.rs

1//! A simple scene to demonstrate picking events for UI and mesh entities.
2
3use bevy::prelude::*;
4
5fn main() {
6    App::new()
7        .add_plugins((DefaultPlugins, MeshPickingPlugin))
8        .add_systems(Startup, setup_scene)
9        .run();
10}
11
12fn setup_scene(
13    mut commands: Commands,
14    mut meshes: ResMut<Assets<Mesh>>,
15    mut materials: ResMut<Assets<StandardMaterial>>,
16) {
17    commands
18        .spawn((
19            Text::new("Click Me to get a box\nDrag cubes to rotate"),
20            Node {
21                position_type: PositionType::Absolute,
22                top: percent(12),
23                left: percent(12),
24                ..default()
25            },
26        ))
27        .observe(on_click_spawn_cube)
28        .observe(|out: On<Pointer<Out>>, mut texts: Query<&mut TextColor>| {
29            let mut text_color = texts.get_mut(out.entity).unwrap();
30            text_color.0 = Color::WHITE;
31        })
32        .observe(
33            |over: On<Pointer<Over>>, mut texts: Query<&mut TextColor>| {
34                let mut color = texts.get_mut(over.entity).unwrap();
35                color.0 = bevy::color::palettes::tailwind::CYAN_400.into();
36            },
37        );
38
39    // Base
40    commands.spawn((
41        Mesh3d(meshes.add(Circle::new(4.0))),
42        MeshMaterial3d(materials.add(Color::WHITE)),
43        Transform::from_rotation(Quat::from_rotation_x(-std::f32::consts::FRAC_PI_2)),
44    ));
45
46    // Light
47    commands.spawn((
48        PointLight {
49            shadows_enabled: true,
50            ..default()
51        },
52        Transform::from_xyz(4.0, 8.0, 4.0),
53    ));
54
55    // Camera
56    commands.spawn((
57        Camera3d::default(),
58        Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
59    ));
60}
61
62fn on_click_spawn_cube(
63    _click: On<Pointer<Click>>,
64    mut commands: Commands,
65    mut meshes: ResMut<Assets<Mesh>>,
66    mut materials: ResMut<Assets<StandardMaterial>>,
67    mut num: Local<usize>,
68) {
69    commands
70        .spawn((
71            Mesh3d(meshes.add(Cuboid::new(0.5, 0.5, 0.5))),
72            MeshMaterial3d(materials.add(Color::srgb_u8(124, 144, 255))),
73            Transform::from_xyz(0.0, 0.25 + 0.55 * *num as f32, 0.0),
74        ))
75        // With the MeshPickingPlugin added, you can add pointer event observers to meshes:
76        .observe(on_drag_rotate);
77    *num += 1;
78}
79
80fn on_drag_rotate(drag: On<Pointer<Drag>>, mut transforms: Query<&mut Transform>) {
81    if let Ok(mut transform) = transforms.get_mut(drag.entity) {
82        transform.rotate_y(drag.delta.x * 0.02);
83        transform.rotate_x(drag.delta.y * 0.02);
84    }
85}
simple_picking/simple_picking.rs

simple_picking/
simple_picking.rs
