Struct bevy::math::cubic_splines::CubicBezier
pub struct CubicBezier<P>where
P: VectorSpace,{ /* private fields */ }
Expand description
A spline composed of a single cubic Bezier curve.
Useful for user-drawn curves with local control, or animation easing. See
CubicSegment::new_bezier
for use in easing.
§Interpolation
The curve only passes through the first and last control point in each set of four points. The curve is divided into “segments” by every fourth control point.
§Tangency
Tangents are manually defined by the two intermediate control points within each set of four points. You can think of the control points the curve passes through as “anchors”, and as the intermediate control points as the anchors displaced along their tangent vectors
§Continuity
A Bezier curve is at minimum C0 continuous, meaning it has no holes or jumps. Each curve segment is C2, meaning the tangent vector changes smoothly between each set of four control points, but this doesn’t hold at the control points between segments. Making the whole curve C1 or C2 requires moving the intermediate control points to align the tangent vectors between segments, and can result in a loss of local control.
§Usage
let points = [[
vec2(-1.0, -20.0),
vec2(3.0, 2.0),
vec2(5.0, 3.0),
vec2(9.0, 8.0),
]];
let bezier = CubicBezier::new(points).to_curve();
let positions: Vec<_> = bezier.iter_positions(100).collect();
Implementations§
§impl<P> CubicBezier<P>where
P: VectorSpace,
impl<P> CubicBezier<P>where
P: VectorSpace,
pub fn new(control_points: impl Into<Vec<[P; 4]>>) -> CubicBezier<P>
pub fn new(control_points: impl Into<Vec<[P; 4]>>) -> CubicBezier<P>
Create a new cubic Bezier curve from sets of control points.
Examples found in repository?
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fn spawn_curve_sprite<T: CurveColor>(commands: &mut Commands, y: f32, points: [T; 4]) {
commands.spawn((
SpriteBundle {
transform: Transform::from_xyz(0., y, 0.),
sprite: Sprite {
custom_size: Some(Vec2::new(75., 75.)),
..Default::default()
},
..Default::default()
},
Curve(CubicBezier::new([points]).to_curve()),
));
}
More examples
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fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
// Define your control points
// These points will define the curve
// You can learn more about bezier curves here
// https://en.wikipedia.org/wiki/B%C3%A9zier_curve
let points = [[
vec3(-6., 2., 0.),
vec3(12., 8., 0.),
vec3(-12., 8., 0.),
vec3(6., 2., 0.),
]];
// Make a CubicCurve
let bezier = CubicBezier::new(points).to_curve();
// Spawning a cube to experiment on
commands.spawn((
PbrBundle {
mesh: meshes.add(Cuboid::default()),
material: materials.add(Color::from(ORANGE)),
transform: Transform::from_translation(points[0][0]),
..default()
},
Curve(bezier),
));
// Some light to see something
commands.spawn(PointLightBundle {
point_light: PointLight {
shadows_enabled: true,
intensity: 10_000_000.,
range: 100.0,
..default()
},
transform: Transform::from_xyz(8., 16., 8.),
..default()
});
// ground plane
commands.spawn(PbrBundle {
mesh: meshes.add(Plane3d::default().mesh().size(50., 50.)),
material: materials.add(Color::from(SILVER)),
..default()
});
// The camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(0., 6., 12.).looking_at(Vec3::new(0., 3., 0.), Vec3::Y),
..default()
});
}
Trait Implementations§
§impl<P> CubicGenerator<P> for CubicBezier<P>where
P: VectorSpace,
impl<P> CubicGenerator<P> for CubicBezier<P>where
P: VectorSpace,
§fn to_curve(&self) -> CubicCurve<P>
fn to_curve(&self) -> CubicCurve<P>
CubicCurve
by computing the interpolation coefficients for each curve segment.Auto Trait Implementations§
impl<P> Freeze for CubicBezier<P>
impl<P> RefUnwindSafe for CubicBezier<P>where
P: RefUnwindSafe,
impl<P> Send for CubicBezier<P>where
P: Send,
impl<P> Sync for CubicBezier<P>where
P: Sync,
impl<P> Unpin for CubicBezier<P>where
P: Unpin,
impl<P> UnwindSafe for CubicBezier<P>where
P: UnwindSafe,
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