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use std::vec;
use fj_interop::ext::SliceExt;
use fj_math::Point;
use crate::{geometry::curve::Curve, objects::Face};
use super::CurveEdgeIntersection;
/// The intersections between a curve and a [`Face`], in curve coordinates
#[derive(Clone, Debug, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub struct CurveFaceIntersection {
/// The intervals where the curve and face intersect, in curve coordinates
pub intervals: Vec<CurveFaceIntersectionInterval>,
}
impl CurveFaceIntersection {
/// Create a new instance from the intersection intervals
///
/// This method is useful for test code.
pub fn from_intervals(
intervals: impl IntoIterator<
Item = impl Into<CurveFaceIntersectionInterval>,
>,
) -> Self {
let intervals = intervals.into_iter().map(Into::into).collect();
Self { intervals }
}
/// Compute the intersection
pub fn compute(curve: &Curve, face: &Face) -> Self {
let half_edges = face.all_cycles().flat_map(|cycle| cycle.half_edges());
let mut intersections = Vec::new();
for half_edge in half_edges {
let intersection = CurveEdgeIntersection::compute(curve, half_edge);
if let Some(intersection) = intersection {
match intersection {
CurveEdgeIntersection::Point { point_on_curve } => {
intersections.push(point_on_curve);
}
CurveEdgeIntersection::Coincident { points_on_curve } => {
intersections.extend(points_on_curve);
}
}
}
}
assert!(intersections.len() % 2 == 0);
intersections.sort();
let intervals = intersections
.as_slice()
.array_chunks_ext()
.map(|&[start, end]| CurveFaceIntersectionInterval { start, end })
.collect();
Self { intervals }
}
/// Merge this intersection list with another
///
/// The merged list will contain all overlaps of the intervals from the two
/// other lists.
pub fn merge(&self, other: &Self) -> Self {
let mut self_intervals = self.intervals.iter().copied();
let mut other_interval = other.intervals.iter().copied();
let mut next_self = self_intervals.next();
let mut next_other = other_interval.next();
let mut intervals = Vec::new();
while let (Some(self_), Some(other)) = (next_self, next_other) {
// If we're starting another loop iteration, we have another
// interval available from both `self` and `other` each. Only if
// that's the case, is there a chance for an overlap.
// Build the overlap of the two next intervals, by comparing them.
// At this point we don't know yet, if this is a valid interval.
let overlap_start = self_.start.max(other.start);
let overlap_end = self_.end.min(other.end);
if overlap_start < overlap_end {
// This is indeed a valid overlap. Add it to our list of
// results.
intervals.push(CurveFaceIntersectionInterval {
start: overlap_start,
end: overlap_end,
});
}
// Only if the end of the overlap interval has overtaken one of the
// input ones are we done with it. An input interval that hasn't
// been overtaken by the overlap, could still overlap with another
// interval.
if self_.end <= overlap_end {
// Current interval from `self` has been overtaken. Let's grab
// the next one.
next_self = self_intervals.next();
}
if other.end <= overlap_end {
// Current interval from `other` has been overtaken. Let's grab
// the next one.
next_other = other_interval.next();
}
}
Self { intervals }
}
/// Indicate whether the intersection list is empty
pub fn is_empty(&self) -> bool {
self.intervals.is_empty()
}
}
impl IntoIterator for CurveFaceIntersection {
type Item = CurveFaceIntersectionInterval;
type IntoIter = vec::IntoIter<Self::Item>;
fn into_iter(self) -> Self::IntoIter {
self.intervals.into_iter()
}
}
/// An intersection between a curve and a face
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub struct CurveFaceIntersectionInterval {
/// The start of the intersection interval, in curve coordinates
pub start: Point<1>,
/// The end of the intersection interval, in curve coordinates
pub end: Point<1>,
}
impl<P> From<[P; 2]> for CurveFaceIntersectionInterval
where
P: Into<Point<1>>,
{
fn from(interval: [P; 2]) -> Self {
let [start, end] = interval.map(Into::into);
Self { start, end }
}
}
#[cfg(test)]
mod tests {
use crate::{
geometry::curve::Curve,
objects::{Cycle, Face},
operations::{BuildCycle, BuildFace, Insert, UpdateFace},
services::Services,
};
use super::CurveFaceIntersection;
#[test]
fn compute() {
let mut services = Services::new();
let (curve, _) = Curve::line_from_points([[-3., 0.], [-2., 0.]]);
#[rustfmt::skip]
let exterior_points = [
[-2., -2.],
[ 2., -2.],
[ 2., 2.],
[-2., 2.],
];
#[rustfmt::skip]
let interior_points = [
[-1., -1.],
[-1., 1.],
[ 1., 1.],
[ 1., -1.],
];
let face =
Face::unbound(services.objects.surfaces.xy_plane(), &mut services)
.update_exterior(|_| {
Cycle::polygon(exterior_points, &mut services)
.insert(&mut services)
})
.add_interiors([Cycle::polygon(
interior_points,
&mut services,
)
.insert(&mut services)]);
let expected =
CurveFaceIntersection::from_intervals([[[1.], [2.]], [[4.], [5.]]]);
assert_eq!(CurveFaceIntersection::compute(&curve, &face), expected);
services.only_validate(face);
}
#[test]
fn merge() {
let a = CurveFaceIntersection::from_intervals([
[[0.], [1.]], // 1: `a` and `b` are equal
[[2.], [5.]], // 2: `a` contains `b`
[[7.], [8.]], // 3: `b` contains `a`
[[9.], [11.]], // 4: overlap; `a` is left
[[14.], [16.]], // 5: overlap; `a` is right
[[18.], [21.]], // 6: one of `a` partially overlaps two of `b`
[[23.], [25.]], // 7: two of `a` partially overlap one of `b`
[[26.], [28.]], // 7
[[31.], [35.]], // 8: partial/complete: one of `a`, two of `b`;
[[36.], [38.]], // 9: partial/complete: two of `a`, one of `b`
[[39.], [40.]], // 9
[[41.], [45.]], // 10: complete/partial: one of `a`, two of `b`
[[48.], [49.]], // 11: complete/partial: two of `a`, one of `b`
[[50.], [52.]], // 11
[[53.], [58.]], // 12: one of `a` overlaps two of `b` completely
[[60.], [61.]], // 13: one of `b` overlaps two of `a` completely
[[62.], [63.]], // 13
[[65.], [66.]], // 14: one of `a` with no overlap in `b`
]);
let b = CurveFaceIntersection::from_intervals([
[[0.], [1.]], // 1
[[3.], [4.]], // 2
[[6.], [9.]], // 3
[[10.], [12.]], // 4
[[13.], [15.]], // 5
[[17.], [19.]], // 6
[[20.], [22.]], // 6
[[24.], [27.]], // 7
[[30.], [32.]], // 8
[[33.], [34.]], // 8
[[37.], [41.]], // 9
[[42.], [43.]], // 10
[[44.], [46.]], // 10
[[47.], [51.]], // 11
[[54.], [55.]], // 12
[[56.], [57.]], // 12
[[59.], [64.]], // 13
]);
let merged = a.merge(&b);
let expected = CurveFaceIntersection::from_intervals([
[[0.], [1.]], // 1
[[3.], [4.]], // 2
[[7.], [8.]], // 3
[[10.], [11.]], // 4
[[14.], [15.]], // 5
[[18.], [19.]], // 6
[[20.], [21.]], // 6
[[24.], [25.]], // 7
[[26.], [27.]], // 7
[[31.], [32.]], // 8
[[33.], [34.]], // 8
[[37.], [38.]], // 9
[[39.], [40.]], // 9
[[42.], [43.]], // 10
[[44.], [45.]], // 10
[[48.], [49.]], // 11
[[50.], [51.]], // 11
[[54.], [55.]], // 12
[[56.], [57.]], // 12
[[60.], [61.]], // 13
[[62.], [63.]], // 13
]);
assert_eq!(merged, expected);
}
}