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Bezier-rs: Implement miter-limit (#1096)

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* Implement miter-limit approximation

* Refactor to use Join enum and address other comments

* Rustdocs improvements

* Tweaks

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>
This commit is contained in:
Hannah Li
2023-03-27 22:58:35 -04:00
committed by Keavon Chambers
co-authored by Keavon Chambers
parent 3733804d18
commit 97be83c404
15 changed files with 106 additions and 69 deletions
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libraries/bezier-rs/src/subpath/solvers.rs
+24 -12
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@@ -9,7 +9,7 @@ use std::f64::consts::PI;
impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
/// Calculate the point on the subpath based on the parametric `t`-value provided.
/// Expects `t` to be within the inclusive range `[0, 1]`.
/// <iframe frameBorder="0" width="100%" height="400px" src="https://graphite.rs/bezier-rs-demos#subpath/evaluate/solo" title="Evaluate Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="350px" src="https://graphite.rs/bezier-rs-demos#subpath/evaluate/solo" title="Evaluate Demo"></iframe>
pub fn evaluate(&self, t: SubpathTValue) -> DVec2 {
let (segment_index, t) = self.t_value_to_parametric(t);
self.get_segment(segment_index).unwrap().evaluate(TValue::Parametric(t))
@@ -23,7 +23,7 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
/// - `error`: an optional f64 value to provide an error bound
/// - `minimum_separation`: the minimum difference two adjacent `t`-values must have when comparing adjacent `t`-values in sorted order.
/// If the comparison condition is not satisfied, the function takes the larger `t`-value of the two.
/// <iframe frameBorder="0" width="100%" height="400px" src="https://graphite.rs/bezier-rs-demos#subpath/intersect-cubic/solo" title="Intersection Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="375px" src="https://graphite.rs/bezier-rs-demos#subpath/intersect-cubic/solo" title="Intersection Demo"></iframe>
pub fn intersections(&self, other: &Bezier, error: Option<f64>, minimum_separation: Option<f64>) -> Vec<(usize, f64)> {
self.iter()
.enumerate()
@@ -35,7 +35,7 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
/// This function expects the following:
/// - other: a [Bezier] curve to check intersections against
/// - error: an optional f64 value to provide an error bound
/// <iframe frameBorder="0" width="100%" height="400px" src="https://graphite.rs/bezier-rs-demos#subpath/intersect-cubic/solo" title="Intersection Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="375px" src="https://graphite.rs/bezier-rs-demos#subpath/intersect-cubic/solo" title="Intersection Demo"></iframe>
pub fn subpath_intersections(&self, other: &Subpath<ManipulatorGroupId>, error: Option<f64>, minimum_separation: Option<f64>) -> Vec<(usize, f64)> {
let mut intersection_t_values: Vec<(usize, f64)> = other.iter().flat_map(|bezier| self.intersections(&bezier, error, minimum_separation)).collect();
intersection_t_values.sort_by(|a, b| a.partial_cmp(b).unwrap());
@@ -48,7 +48,7 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
/// If the comparison condition is not satisfied, the function takes the larger `t`-value of the two
///
/// **NOTE**: if an intersection were to occur within an `error` distance away from an anchor point, the algorithm will filter that intersection out.
/// <iframe frameBorder="0" width="100%" height="350px" src="https://graphite.rs/bezier-rs-demos#subpath/self-intersect/solo" title="Self-Intersection Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="375px" src="https://graphite.rs/bezier-rs-demos#subpath/self-intersect/solo" title="Self-Intersection Demo"></iframe>
pub fn self_intersections(&self, error: Option<f64>, minimum_separation: Option<f64>) -> Vec<(usize, f64)> {
let mut intersections_vec = Vec::new();
let err = error.unwrap_or(MAX_ABSOLUTE_DIFFERENCE);
@@ -69,14 +69,14 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
}
/// Returns a normalized unit vector representing the tangent on the subpath based on the parametric `t`-value provided.
/// <iframe frameBorder="0" width="100%" height="400px" src="https://graphite.rs/bezier-rs-demos#subpath/tangent/solo" title="Tangent Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="350px" src="https://graphite.rs/bezier-rs-demos#subpath/tangent/solo" title="Tangent Demo"></iframe>
pub fn tangent(&self, t: SubpathTValue) -> DVec2 {
let (segment_index, t) = self.t_value_to_parametric(t);
self.get_segment(segment_index).unwrap().tangent(TValue::Parametric(t))
}
/// Returns a normalized unit vector representing the direction of the normal on the subpath based on the parametric `t`-value provided.
/// <iframe frameBorder="0" width="100%" height="400px" src="https://graphite.rs/bezier-rs-demos#subpath/normal/solo" title="Normal Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="350px" src="https://graphite.rs/bezier-rs-demos#subpath/normal/solo" title="Normal Demo"></iframe>
pub fn normal(&self, t: SubpathTValue) -> DVec2 {
let (segment_index, t) = self.t_value_to_parametric(t);
self.get_segment(segment_index).unwrap().normal(TValue::Parametric(t))
@@ -84,7 +84,7 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
/// Returns two lists of `t`-values representing the local extrema of the `x` and `y` parametric subpaths respectively.
/// The list of `t`-values returned are filtered such that they fall within the range `[0, 1]`.
/// <iframe frameBorder="0" width="100%" height="325px" src="https://graphite.rs/bezier-rs-demos#subpath/local-extrema/solo" title="Local Extrema Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="300px" src="https://graphite.rs/bezier-rs-demos#subpath/local-extrema/solo" title="Local Extrema Demo"></iframe>
pub fn local_extrema(&self) -> [Vec<f64>; 2] {
let number_of_curves = self.len_segments() as f64;
@@ -99,7 +99,7 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
}
/// Return the min and max corners that represent the bounding box of the subpath.
/// <iframe frameBorder="0" width="100%" height="325px" src="https://graphite.rs/bezier-rs-demos#subpath/bounding-box/solo" title="Bounding Box Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="300px" src="https://graphite.rs/bezier-rs-demos#subpath/bounding-box/solo" title="Bounding Box Demo"></iframe>
pub fn bounding_box(&self) -> Option<[DVec2; 2]> {
self.iter().map(|bezier| bezier.bounding_box()).reduce(|bbox1, bbox2| [bbox1[0].min(bbox2[0]), bbox1[1].max(bbox2[1])])
}
@@ -138,7 +138,15 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
}
/// Returns the manipulator point that is needed for a miter join if it is possible.
pub(crate) fn miter_line_join(&self, other: &Subpath<ManipulatorGroupId>) -> Option<ManipulatorGroup<ManipulatorGroupId>> {
/// - `miter_limit`: Defines a limit for the ratio between the miter length and the stroke width.
/// Alternatively, this can be interpreted as limiting the angle that the miter can form.
/// When the limit is exceeded, no manipulator group will be returned.
/// This value should be at least 1. If not, the default of 4 will be used.
pub(crate) fn miter_line_join(&self, other: &Subpath<ManipulatorGroupId>, miter_limit: Option<f64>) -> Option<ManipulatorGroup<ManipulatorGroupId>> {
let miter_limit = match miter_limit {
Some(miter_limit) if miter_limit >= 1. => miter_limit,
_ => 4.,
};
let in_segment = self.get_segment(self.len_segments() - 1).unwrap();
let out_segment = other.get_segment(0).unwrap();
let in_tangent = in_segment.tangent(TValue::Parametric(1.));
@@ -151,9 +159,13 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
if !normalized_in_tangent.abs_diff_eq(normalized_out_tangent, MAX_ABSOLUTE_DIFFERENCE) && !normalized_in_tangent.abs_diff_eq(-normalized_out_tangent, MAX_ABSOLUTE_DIFFERENCE) {
let intersection = line_intersection(in_segment.end(), in_tangent, out_segment.start(), out_tangent);
let start_to_intersection = intersection - in_segment.end();
let intersection_to_end = out_segment.start() - intersection;
// Draw the miter join if the intersection occurs in the correct direction with respect to the path
if (intersection - in_segment.end()).normalize().abs_diff_eq(in_tangent, MAX_ABSOLUTE_DIFFERENCE)
&& (out_segment.start() - intersection).normalize().abs_diff_eq(out_tangent, MAX_ABSOLUTE_DIFFERENCE)
if start_to_intersection.normalize().abs_diff_eq(in_tangent, MAX_ABSOLUTE_DIFFERENCE)
&& intersection_to_end.normalize().abs_diff_eq(out_tangent, MAX_ABSOLUTE_DIFFERENCE)
&& miter_limit >= 1. / (start_to_intersection.angle_between(-intersection_to_end).abs() / 2.).sin()
{
return Some(ManipulatorGroup {
anchor: intersection,
@@ -225,7 +237,7 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
/// Returns the curvature, a scalar value for the derivative at the point `t` along the subpath.
/// Curvature is 1 over the radius of a circle with an equivalent derivative.
/// <iframe frameBorder="0" width="100%" height="400px" src="https://graphite.rs/bezier-rs-demos#subpath/curvature/solo" title="Curvature Demo"></iframe>
/// <iframe frameBorder="0" width="100%" height="350px" src="https://graphite.rs/bezier-rs-demos#subpath/curvature/solo" title="Curvature Demo"></iframe>
pub fn curvature(&self, t: SubpathTValue) -> f64 {
let (segment_index, t) = self.t_value_to_parametric(t);
self.get_segment(segment_index).unwrap().curvature(TValue::Parametric(t))