087a345579
# Objective A Bezier curve is a curve defined by two or more control points. In the simplest form, it's just a line. The (arguably) most common type of Bezier curve is a cubic Bezier, defined by four control points. These are often used in animation, etc. Bevy has a Bezier curve struct called `Bezier`. However, this is technically a misnomer as it only represents cubic Bezier curves. ## Solution This PR changes the struct name to `CubicBezier` to more accurately reflect the struct's usage. Since it's exposed in Bevy's prelude, it can potentially collide with other `Bezier` implementations. While that might instead be an argument for removing it from the prelude, there's also something to be said for adding a more general `Bezier` into Bevy, in which case we'd likely want to use the name `Bezier`. As a final motivator, not only is the struct located in `cubic_spines.rs`, there are also several other spline-related structs which follow the `CubicXxx` naming convention where applicable. For example, `CubicSegment` represents a cubic Bezier curve (with coefficients pre-baked). --- ## Migration Guide - Change all `Bezier` references to `CubicBezier`
90 lines
2.4 KiB
Rust
90 lines
2.4 KiB
Rust
//! Demonstrates how to work with Cubic curves.
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use bevy::{
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math::{cubic_splines::CubicCurve, vec3},
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prelude::*,
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};
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#[derive(Component)]
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pub struct Curve(CubicCurve<Vec3>);
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.add_systems(Update, animate_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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// Define your control points
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// These points will define the curve
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// You can learn more about bezier curves here
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// https://en.wikipedia.org/wiki/B%C3%A9zier_curve
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let points = [[
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vec3(-6., 2., 0.),
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vec3(12., 8., 0.),
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vec3(-12., 8., 0.),
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vec3(6., 2., 0.),
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]];
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// Make a CubicCurve
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let bezier = CubicBezier::new(points).to_curve();
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// Spawning a cube to experiment on
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commands.spawn((
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PbrBundle {
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mesh: meshes.add(shape::Cube::default().into()),
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material: materials.add(Color::ORANGE.into()),
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transform: Transform::from_translation(points[0][0]),
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..default()
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},
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Curve(bezier),
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));
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// Some light to see something
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commands.spawn(PointLightBundle {
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point_light: PointLight {
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intensity: 9000.,
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range: 100.,
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shadows_enabled: true,
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..default()
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},
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transform: Transform::from_xyz(8., 16., 8.),
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..default()
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});
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// ground plane
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commands.spawn(PbrBundle {
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mesh: meshes.add(shape::Plane::from_size(50.).into()),
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material: materials.add(Color::SILVER.into()),
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..default()
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});
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// The camera
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(0., 6., 12.).looking_at(Vec3::new(0., 3., 0.), Vec3::Y),
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..default()
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});
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}
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pub fn animate_cube(
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time: Res<Time>,
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mut query: Query<(&mut Transform, &Curve)>,
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mut gizmos: Gizmos,
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) {
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let t = (time.elapsed_seconds().sin() + 1.) / 2.;
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for (mut transform, cubic_curve) in &mut query {
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// Draw the curve
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gizmos.linestrip(cubic_curve.0.iter_positions(50), Color::WHITE);
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// position takes a point from the curve where 0 is the initial point
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// and 1 is the last point
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transform.translation = cubic_curve.0.position(t);
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}
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}
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