animated_transform/
animated_transform.rs

1//! Create and play an animation defined by code that operates on the [`Transform`] component.
2
3use std::f32::consts::PI;
4
5use bevy::{
6    animation::{animated_field, AnimationTarget, AnimationTargetId},
7    prelude::*,
8};
9
10fn main() {
11    App::new()
12        .add_plugins(DefaultPlugins)
13        .insert_resource(AmbientLight {
14            color: Color::WHITE,
15            brightness: 150.0,
16            ..default()
17        })
18        .add_systems(Startup, setup)
19        .run();
20}
21
22fn setup(
23    mut commands: Commands,
24    mut meshes: ResMut<Assets<Mesh>>,
25    mut materials: ResMut<Assets<StandardMaterial>>,
26    mut animations: ResMut<Assets<AnimationClip>>,
27    mut graphs: ResMut<Assets<AnimationGraph>>,
28) {
29    // Camera
30    commands.spawn((
31        Camera3d::default(),
32        Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
33    ));
34
35    // Light
36    commands.spawn((
37        PointLight {
38            intensity: 500_000.0,
39            ..default()
40        },
41        Transform::from_xyz(0.0, 2.5, 0.0),
42    ));
43
44    // Let's use the `Name` component to target entities. We can use anything we
45    // like, but names are convenient.
46    let planet = Name::new("planet");
47    let orbit_controller = Name::new("orbit_controller");
48    let satellite = Name::new("satellite");
49
50    // Creating the animation
51    let mut animation = AnimationClip::default();
52    // A curve can modify a single part of a transform: here, the translation.
53    let planet_animation_target_id = AnimationTargetId::from_name(&planet);
54    animation.add_curve_to_target(
55        planet_animation_target_id,
56        AnimatableCurve::new(
57            animated_field!(Transform::translation),
58            UnevenSampleAutoCurve::new([0.0, 1.0, 2.0, 3.0, 4.0].into_iter().zip([
59                Vec3::new(1.0, 0.0, 1.0),
60                Vec3::new(-1.0, 0.0, 1.0),
61                Vec3::new(-1.0, 0.0, -1.0),
62                Vec3::new(1.0, 0.0, -1.0),
63                // in case seamless looping is wanted, the last keyframe should
64                // be the same as the first one
65                Vec3::new(1.0, 0.0, 1.0),
66            ]))
67            .expect("should be able to build translation curve because we pass in valid samples"),
68        ),
69    );
70    // Or it can modify the rotation of the transform.
71    // To find the entity to modify, the hierarchy will be traversed looking for
72    // an entity with the right name at each level.
73    let orbit_controller_animation_target_id =
74        AnimationTargetId::from_names([planet.clone(), orbit_controller.clone()].iter());
75    animation.add_curve_to_target(
76        orbit_controller_animation_target_id,
77        AnimatableCurve::new(
78            animated_field!(Transform::rotation),
79            UnevenSampleAutoCurve::new([0.0, 1.0, 2.0, 3.0, 4.0].into_iter().zip([
80                Quat::IDENTITY,
81                Quat::from_axis_angle(Vec3::Y, PI / 2.),
82                Quat::from_axis_angle(Vec3::Y, PI / 2. * 2.),
83                Quat::from_axis_angle(Vec3::Y, PI / 2. * 3.),
84                Quat::IDENTITY,
85            ]))
86            .expect("Failed to build rotation curve"),
87        ),
88    );
89    // If a curve in an animation is shorter than the other, it will not repeat
90    // until all other curves are finished. In that case, another animation should
91    // be created for each part that would have a different duration / period.
92    let satellite_animation_target_id = AnimationTargetId::from_names(
93        [planet.clone(), orbit_controller.clone(), satellite.clone()].iter(),
94    );
95    animation.add_curve_to_target(
96        satellite_animation_target_id,
97        AnimatableCurve::new(
98            animated_field!(Transform::scale),
99            UnevenSampleAutoCurve::new(
100                [0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0]
101                    .into_iter()
102                    .zip([
103                        Vec3::splat(0.8),
104                        Vec3::splat(1.2),
105                        Vec3::splat(0.8),
106                        Vec3::splat(1.2),
107                        Vec3::splat(0.8),
108                        Vec3::splat(1.2),
109                        Vec3::splat(0.8),
110                        Vec3::splat(1.2),
111                        Vec3::splat(0.8),
112                    ]),
113            )
114            .expect("Failed to build scale curve"),
115        ),
116    );
117    // There can be more than one curve targeting the same entity path.
118    animation.add_curve_to_target(
119        AnimationTargetId::from_names(
120            [planet.clone(), orbit_controller.clone(), satellite.clone()].iter(),
121        ),
122        AnimatableCurve::new(
123            animated_field!(Transform::rotation),
124            UnevenSampleAutoCurve::new([0.0, 1.0, 2.0, 3.0, 4.0].into_iter().zip([
125                Quat::IDENTITY,
126                Quat::from_axis_angle(Vec3::Y, PI / 2.),
127                Quat::from_axis_angle(Vec3::Y, PI / 2. * 2.),
128                Quat::from_axis_angle(Vec3::Y, PI / 2. * 3.),
129                Quat::IDENTITY,
130            ]))
131            .expect("should be able to build translation curve because we pass in valid samples"),
132        ),
133    );
134
135    // Create the animation graph
136    let (graph, animation_index) = AnimationGraph::from_clip(animations.add(animation));
137
138    // Create the animation player, and set it to repeat
139    let mut player = AnimationPlayer::default();
140    player.play(animation_index).repeat();
141
142    // Create the scene that will be animated
143    // First entity is the planet
144    let planet_entity = commands
145        .spawn((
146            Mesh3d(meshes.add(Sphere::default())),
147            MeshMaterial3d(materials.add(Color::srgb(0.8, 0.7, 0.6))),
148            // Add the animation graph and player
149            planet,
150            AnimationGraphHandle(graphs.add(graph)),
151            player,
152        ))
153        .id();
154    commands
155        .entity(planet_entity)
156        .insert(AnimationTarget {
157            id: planet_animation_target_id,
158            player: planet_entity,
159        })
160        .with_children(|p| {
161            // This entity is just used for animation, but doesn't display anything
162            p.spawn((
163                Transform::default(),
164                Visibility::default(),
165                orbit_controller,
166                AnimationTarget {
167                    id: orbit_controller_animation_target_id,
168                    player: planet_entity,
169                },
170            ))
171            .with_children(|p| {
172                // The satellite, placed at a distance of the planet
173                p.spawn((
174                    Mesh3d(meshes.add(Cuboid::new(0.5, 0.5, 0.5))),
175                    MeshMaterial3d(materials.add(Color::srgb(0.3, 0.9, 0.3))),
176                    Transform::from_xyz(1.5, 0.0, 0.0),
177                    AnimationTarget {
178                        id: satellite_animation_target_id,
179                        player: planet_entity,
180                    },
181                    satellite,
182                ));
183            });
184        });
185}
animated_transform/animated_transform.rs

animated_transform/
animated_transform.rs
