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: Val::Percent(12.0),
23                left: Val::Percent(12.0),
24                ..default()
25            },
26        ))
27        .observe(on_click_spawn_cube)
28        .observe(
29            |out: Trigger<Pointer<Out>>, mut texts: Query<&mut TextColor>| {
30                let mut text_color = texts.get_mut(out.target()).unwrap();
31                text_color.0 = Color::WHITE;
32            },
33        )
34        .observe(
35            |over: Trigger<Pointer<Over>>, mut texts: Query<&mut TextColor>| {
36                let mut color = texts.get_mut(over.target()).unwrap();
37                color.0 = bevy::color::palettes::tailwind::CYAN_400.into();
38            },
39        );
40
41    // Base
42    commands.spawn((
43        Mesh3d(meshes.add(Circle::new(4.0))),
44        MeshMaterial3d(materials.add(Color::WHITE)),
45        Transform::from_rotation(Quat::from_rotation_x(-std::f32::consts::FRAC_PI_2)),
46    ));
47
48    // Light
49    commands.spawn((
50        PointLight {
51            shadows_enabled: true,
52            ..default()
53        },
54        Transform::from_xyz(4.0, 8.0, 4.0),
55    ));
56
57    // Camera
58    commands.spawn((
59        Camera3d::default(),
60        Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
61    ));
62}
63
64fn on_click_spawn_cube(
65    _click: Trigger<Pointer<Click>>,
66    mut commands: Commands,
67    mut meshes: ResMut<Assets<Mesh>>,
68    mut materials: ResMut<Assets<StandardMaterial>>,
69    mut num: Local<usize>,
70) {
71    commands
72        .spawn((
73            Mesh3d(meshes.add(Cuboid::new(0.5, 0.5, 0.5))),
74            MeshMaterial3d(materials.add(Color::srgb_u8(124, 144, 255))),
75            Transform::from_xyz(0.0, 0.25 + 0.55 * *num as f32, 0.0),
76        ))
77        // With the MeshPickingPlugin added, you can add pointer event observers to meshes:
78        .observe(on_drag_rotate);
79    *num += 1;
80}
81
82fn on_drag_rotate(drag: Trigger<Pointer<Drag>>, mut transforms: Query<&mut Transform>) {
83    if let Ok(mut transform) = transforms.get_mut(drag.target()) {
84        transform.rotate_y(drag.delta.x * 0.02);
85        transform.rotate_x(drag.delta.y * 0.02);
86    }
87}
simple_picking/simple_picking.rs

simple_picking/
simple_picking.rs
