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https://github.com/bevyengine/bevy
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65252bb87a
Examples inconsistently use either `TAU`, `PI`, `FRAC_PI_2` or `FRAC_PI_4`. Often in odd ways and without `use`ing the constants, making it difficult to parse. * Use `PI` to specify angles. * General code-quality improvements. * Fix borked `hierarchy` example. Co-authored-by: devil-ira <justthecooldude@gmail.com>
99 lines
3.5 KiB
Rust
99 lines
3.5 KiB
Rust
//! Illustrates how to scale an object in each direction.
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use std::f32::consts::PI;
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use bevy::math::Vec3Swizzles;
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use bevy::prelude::*;
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// Define a component to keep information for the scaled object.
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#[derive(Component)]
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struct Scaling {
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scale_direction: Vec3,
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scale_speed: f32,
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max_element_size: f32,
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min_element_size: f32,
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}
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// Implement a simple initialization.
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impl Scaling {
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fn new() -> Self {
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Scaling {
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scale_direction: Vec3::X,
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scale_speed: 2.0,
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max_element_size: 5.0,
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min_element_size: 1.0,
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}
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}
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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(change_scale_direction)
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.add_system(scale_cube)
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.run();
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}
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// Startup system to setup the scene and spawn all relevant entities.
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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 scale.
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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_rotation(Quat::from_rotation_y(PI / 4.0)),
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..default()
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})
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.insert(Scaling::new());
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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 for better 3d visibility.
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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 check if a scaled entity went above or below the entities scaling bounds
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// and change the direction of the scaling vector.
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fn change_scale_direction(mut cubes: Query<(&mut Transform, &mut Scaling)>) {
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for (mut transform, mut cube) in &mut cubes {
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// If an entity scaled beyond the maximum of its size in any dimension
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// the scaling vector is flipped so the scaling is gradually reverted.
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// Additionally, to ensure the condition does not trigger again we floor the elements to
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// their next full value, which should be max_element_size at max.
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if transform.scale.max_element() > cube.max_element_size {
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cube.scale_direction *= -1.0;
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transform.scale = transform.scale.floor();
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}
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// If an entity scaled beyond the minimum of its size in any dimension
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// the scaling vector is also flipped.
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// Additionally the Values are ceiled to be min_element_size at least
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// and the scale direction is flipped.
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// This way the entity will change the dimension in which it is scaled any time it
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// reaches its min_element_size.
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if transform.scale.min_element() < cube.min_element_size {
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cube.scale_direction *= -1.0;
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transform.scale = transform.scale.ceil();
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cube.scale_direction = cube.scale_direction.zxy();
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}
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}
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}
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// This system will scale any entity with assigned Scaling in each direction
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// by cycling through the directions to scale.
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fn scale_cube(mut cubes: Query<(&mut Transform, &Scaling)>, timer: Res<Time>) {
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for (mut transform, cube) in &mut cubes {
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transform.scale += cube.scale_direction * cube.scale_speed * timer.delta_seconds();
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}
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}
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