Struct epaint::CubicBezierShape
source · [−]pub struct CubicBezierShape {
pub points: [Pos2; 4],
pub closed: bool,
pub fill: Color32,
pub stroke: Stroke,
}
Expand description
A cubic Bézier Curve.
See also QuadraticBezierShape
.
Fields
points: [Pos2; 4]
The first point is the starting point and the last one is the ending point of the curve. The middle points are the control points.
closed: bool
fill: Color32
stroke: Stroke
Implementations
sourceimpl CubicBezierShape
impl CubicBezierShape
sourcepub fn from_points_stroke(
points: [Pos2; 4],
closed: bool,
fill: Color32,
stroke: impl Into<Stroke>
) -> Self
pub fn from_points_stroke(
points: [Pos2; 4],
closed: bool,
fill: Color32,
stroke: impl Into<Stroke>
) -> Self
Creates a cubic Bézier curve based on 4 points and stroke.
The first point is the starting point and the last one is the ending point of the curve. The middle points are the control points.
sourcepub fn transform(&self, transform: &RectTransform) -> Self
pub fn transform(&self, transform: &RectTransform) -> Self
Transform the curve with the given transform.
sourcepub fn to_path_shapes(
&self,
tolerance: Option<f32>,
epsilon: Option<f32>
) -> Vec<PathShape>
pub fn to_path_shapes(
&self,
tolerance: Option<f32>,
epsilon: Option<f32>
) -> Vec<PathShape>
Convert the cubic Bézier curve to one or two PathShape
’s.
When the curve is closed and it has to intersect with the base line, it will be converted into two shapes.
Otherwise, it will be converted into one shape.
The tolerance
will be used to control the max distance between the curve and the base line.
The epsilon
is used when comparing two floats.
sourcepub fn visual_bounding_rect(&self) -> Rect
pub fn visual_bounding_rect(&self) -> Rect
The visual bounding rectangle (includes stroke width)
sourcepub fn logical_bounding_rect(&self) -> Rect
pub fn logical_bounding_rect(&self) -> Rect
Logical bounding rectangle (ignoring stroke width)
sourcepub fn split_range(&self, t_range: Range<f32>) -> Self
pub fn split_range(&self, t_range: Range<f32>) -> Self
split the original cubic curve into a new one within a range.
pub fn num_quadratics(&self, tolerance: f32) -> u32
sourcepub fn find_cross_t(&self, epsilon: f32) -> Option<f32>
pub fn find_cross_t(&self, epsilon: f32) -> Option<f32>
Find out the t value for the point where the curve is intersected with the base line. The base line is the line from P0 to P3. If the curve only has two intersection points with the base line, they should be 0.0 and 1.0. In this case, the “fill” will be simple since the curve is a convex line. If the curve has more than two intersection points with the base line, the “fill” will be a problem. We need to find out where is the 3rd t value (0<t<1) And the original cubic curve will be split into two curves (0.0..t and t..1.0). B(t) = (1-t)^3P0 + 3t*(1-t)^2P1 + 3t^2*(1-t)P2 + t^3P3 or B(t) = (P3 - 3P2 + 3P1 - P0)t^3 + (3P2 - 6P1 + 3P0)t^2 + (3P1 - 3P0)t + P0 this B(t) should be on the line between P0 and P3. Therefore: (B.x - P0.x)/(P3.x - P0.x) = (B.y - P0.y)/(P3.y - P0.y), or: B.x * (P3.y - P0.y) - B.y * (P3.x - P0.x) + P0.x * (P0.y - P3.y) + P0.y * (P3.x - P0.x) = 0 B.x = (P3.x - 3 * P2.x + 3 * P1.x - P0.x) * t^3 + (3 * P2.x - 6 * P1.x + 3 * P0.x) * t^2 + (3 * P1.x - 3 * P0.x) * t + P0.x B.y = (P3.y - 3 * P2.y + 3 * P1.y - P0.y) * t^3 + (3 * P2.y - 6 * P1.y + 3 * P0.y) * t^2 + (3 * P1.y - 3 * P0.y) * t + P0.y Combine the above three equations and iliminate B.x and B.y, we get: t^3 * ( (P3.x - 3P2.x + 3P1.x - P0.x) * (P3.y - P0.y) - (P3.y - 3P2.y + 3P1.y - P0.y) * (P3.x - P0.x))
- t^2 * ( (3 * P2.x - 6 * P1.x + 3 * P0.x) * (P3.y - P0.y) - (3 * P2.y - 6 * P1.y + 3 * P0.y) * (P3.x - P0.x))
- t^1 * ( (3 * P1.x - 3 * P0.x) * (P3.y - P0.y) - (3 * P1.y - 3 * P0.y) * (P3.x - P0.x))
- (P0.x * (P3.y - P0.y) - P0.y * (P3.x - P0.x)) + P0.x * (P0.y - P3.y) + P0.y * (P3.x - P0.x) = 0 or a * t^3 + b * t^2 + c * t + d = 0
let x = t - b / (3 * a), then we have: x^3 + p * x + q = 0, where: p = (3.0 * a * c - b^2) / (3.0 * a^2) q = (2.0 * b^3 - 9.0 * a * b * c + 27.0 * a^2 * d) / (27.0 * a^3)
when p > 0, there will be one real root, two complex roots
when p = 0, there will be two real roots, when p=q=0, there will be three real roots but all 0.
when p < 0, there will be three unique real roots. this is what we need. (x1, x2, x3)
t = x + b / (3 * a), then we have: t1, t2, t3.
the one between 0.0 and 1.0 is what we need.
<https://baike.baidu.com/item/%E4%B8%80%E5%85%83%E4%B8%89%E6%AC%A1%E6%96%B9%E7%A8%8B/8388473 /
>
sourcepub fn sample(&self, t: f32) -> Pos2
pub fn sample(&self, t: f32) -> Pos2
Calculate the point (x,y) at t based on the cubic Bézier curve equation. t is in [0.0,1.0] Bézier Curve
sourcepub fn flatten(&self, tolerance: Option<f32>) -> Vec<Pos2>
pub fn flatten(&self, tolerance: Option<f32>) -> Vec<Pos2>
find a set of points that approximate the cubic Bézier curve. the number of points is determined by the tolerance. the points may not be evenly distributed in the range [0.0,1.0] (t value)
sourcepub fn flatten_closed(
&self,
tolerance: Option<f32>,
epsilon: Option<f32>
) -> Vec<Vec<Pos2>>
pub fn flatten_closed(
&self,
tolerance: Option<f32>,
epsilon: Option<f32>
) -> Vec<Vec<Pos2>>
find a set of points that approximate the cubic Bézier curve. the number of points is determined by the tolerance. the points may not be evenly distributed in the range [0.0,1.0] (t value) this api will check whether the curve will cross the base line or not when closed = true. The result will be a vec of vec of Pos2. it will store two closed aren in different vec. The epsilon is used to compare a float value.
Trait Implementations
sourceimpl Clone for CubicBezierShape
impl Clone for CubicBezierShape
sourcefn clone(&self) -> CubicBezierShape
fn clone(&self) -> CubicBezierShape
Returns a copy of the value. Read more
1.0.0 · sourcefn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
sourceimpl Debug for CubicBezierShape
impl Debug for CubicBezierShape
sourceimpl<'de> Deserialize<'de> for CubicBezierShape
impl<'de> Deserialize<'de> for CubicBezierShape
sourcefn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
__D: Deserializer<'de>,
fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
__D: Deserializer<'de>,
Deserialize this value from the given Serde deserializer. Read more
sourceimpl From<CubicBezierShape> for Shape
impl From<CubicBezierShape> for Shape
sourcefn from(shape: CubicBezierShape) -> Self
fn from(shape: CubicBezierShape) -> Self
Converts to this type from the input type.
sourceimpl PartialEq<CubicBezierShape> for CubicBezierShape
impl PartialEq<CubicBezierShape> for CubicBezierShape
sourcefn eq(&self, other: &CubicBezierShape) -> bool
fn eq(&self, other: &CubicBezierShape) -> bool
This method tests for self
and other
values to be equal, and is used
by ==
. Read more
sourcefn ne(&self, other: &CubicBezierShape) -> bool
fn ne(&self, other: &CubicBezierShape) -> bool
This method tests for !=
.
sourceimpl Serialize for CubicBezierShape
impl Serialize for CubicBezierShape
impl Copy for CubicBezierShape
impl StructuralPartialEq for CubicBezierShape
Auto Trait Implementations
impl RefUnwindSafe for CubicBezierShape
impl Send for CubicBezierShape
impl Sync for CubicBezierShape
impl Unpin for CubicBezierShape
impl UnwindSafe for CubicBezierShape
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcefn clone_into(&self, target: &mut T)
fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more