ea13f0bddf
# Objective Users often ask for help with rotations as they struggle with `Quat`s. `Quat` is rather complex and has a ton of verbose methods. ## Solution Add rotation helper methods to `Transform`. Co-authored-by: devil-ira <justthecooldude@gmail.com>
58 lines
1.8 KiB
Rust
58 lines
1.8 KiB
Rust
//! Illustrates how to rotate an object around an axis.
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use bevy::prelude::*;
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use std::f32::consts::TAU;
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// Define a component to designate a rotation speed to an entity.
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#[derive(Component)]
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struct Rotatable {
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speed: f32,
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}
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_startup_system(setup)
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.add_system(rotate_cube)
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.run();
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}
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fn setup(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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) {
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// Spawn a cube to rotate.
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commands
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.spawn_bundle(PbrBundle {
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mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
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material: materials.add(Color::WHITE.into()),
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transform: Transform::from_translation(Vec3::ZERO),
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..default()
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})
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.insert(Rotatable { speed: 0.3 });
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// Spawn a camera looking at the entities to show what's happening in this example.
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commands.spawn_bundle(Camera3dBundle {
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transform: Transform::from_xyz(0.0, 10.0, 20.0).looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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});
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// Add a light source so we can see clearly.
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commands.spawn_bundle(PointLightBundle {
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transform: Transform::from_translation(Vec3::ONE * 3.0),
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..default()
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});
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}
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// This system will rotate any entity in the scene with a Rotatable component around its y-axis.
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fn rotate_cube(mut cubes: Query<(&mut Transform, &Rotatable)>, timer: Res<Time>) {
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for (mut transform, cube) in cubes.iter_mut() {
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// The speed is first multiplied by TAU which is a full rotation (360deg) in radians,
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// and then multiplied by delta_seconds which is the time that passed last frame.
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// In other words. Speed is equal to the amount of rotations per second.
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transform.rotate_y(cube.speed * TAU * timer.delta_seconds());
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}
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}
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