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use geo_types::{Coord, Line, Point, Triangle};
use spade::{
ConstrainedDelaunayTriangulation, DelaunayTriangulation, Point2, SpadeNum, Triangulation,
};
use crate::{
line_intersection::line_intersection, CoordsIter, EuclideanDistance, GeoFloat,
LineIntersection, LinesIter,
};
use crate::{Centroid, Contains};
// ======== Config ============
/// Collection of parameters that influence the precision of the algorithm in some sense (see
/// explanations on fields of this struct)
///
/// This implements the `Default` trait and you can just use it most of the time
#[derive(Debug, Clone)]
pub struct SpadeTriangulationConfig<T: SpadeTriangulationFloat> {
/// Coordinates within this radius are snapped to the same position. For any two `Coords` there's
/// no real way to influence the decision when choosing the snapper and the snappee
pub snap_radius: T,
}
impl<T> Default for SpadeTriangulationConfig<T>
where
T: SpadeTriangulationFloat,
{
fn default() -> Self {
Self {
snap_radius: <T as std::convert::From<f32>>::from(0.000_1),
}
}
}
// ====== Error ========
#[derive(Debug)]
pub enum TriangulationError {
SpadeError(spade::InsertionError),
LoopTrap,
ConstraintFailure,
}
impl std::fmt::Display for TriangulationError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{:?}", self)
}
}
impl std::error::Error for TriangulationError {}
pub type TriangulationResult<T> = Result<T, TriangulationError>;
// ======= Float trait ========
pub trait SpadeTriangulationFloat: GeoFloat + SpadeNum {}
impl<T: GeoFloat + SpadeNum> SpadeTriangulationFloat for T {}
// ======= Triangulation trait =========
pub type Triangles<T> = Vec<Triangle<T>>;
// seal the trait that needs to be implemented for TriangulateSpade to be implemented. This is done
// so that we don't leak these weird methods on the public interface.
mod private {
use super::*;
pub(crate) type CoordsIter<'a, T> = Box<dyn Iterator<Item = Coord<T>> + 'a>;
pub trait TriangulationRequirementTrait<'a, T>
where
T: SpadeTriangulationFloat,
{
/// collect all the lines that are relevant for triangulations from the geometric object that
/// should be triangulated.
///
/// intersecting lines are allowed
fn lines(&'a self) -> Vec<Line<T>>;
/// collect all the coords that are relevant for triangulations from the geometric object that
/// should be triangulated
fn coords(&'a self) -> CoordsIter<T>;
/// define a predicate that decides if a point is inside of the object (used for constrained triangulation)
fn contains_point(&'a self, p: Point<T>) -> bool;
// processing of the lines that prepare the lines for triangulation.
//
// `spade` has the general limitation that constraint lines cannot intersect or else it
// will panic. This is why we need to manually split up the lines into smaller parts at the
// intersection point
//
// there's also a preprocessing step which tries to minimize the risk of failure of the algo
// through edge cases (thin/flat triangles are prevented as much as possible & lines are deduped, ...)
fn cleanup_lines(lines: Vec<Line<T>>, snap_radius: T) -> TriangulationResult<Vec<Line<T>>> {
let (known_coords, lines) = preprocess_lines(lines, snap_radius);
prepare_intersection_contraint(lines, known_coords, snap_radius)
}
}
}
/// Triangulate polygons using a [Delaunay
/// Triangulation](https://en.wikipedia.org/wiki/Delaunay_triangulation)
///
/// This trait contains both constrained and unconstrained triangulation methods. To read more
/// about the differences of these methods also consult [this
/// page](https://en.wikipedia.org/wiki/Constrained_Delaunay_triangulation)
pub trait TriangulateSpade<'a, T>: private::TriangulationRequirementTrait<'a, T>
where
T: SpadeTriangulationFloat,
{
/// returns a triangulation that's solely based on the points of the geometric object
///
/// The triangulation is guaranteed to be Delaunay
///
/// Note that the lines of the triangulation don't necessarily follow the lines of the input
/// geometry. If you wish to achieve that take a look at the `constrained_triangulation` and the
/// `constrained_outer_triangulation` functions.
///
/// ```rust
/// use geo::TriangulateSpade;
/// use geo::{Polygon, LineString, Coord};
/// let u_shape = Polygon::new(
/// LineString::new(vec![
/// Coord { x: 0.0, y: 0.0 },
/// Coord { x: 1.0, y: 0.0 },
/// Coord { x: 1.0, y: 1.0 },
/// Coord { x: 2.0, y: 1.0 },
/// Coord { x: 2.0, y: 0.0 },
/// Coord { x: 3.0, y: 0.0 },
/// Coord { x: 3.0, y: 3.0 },
/// Coord { x: 0.0, y: 3.0 },
/// ]),
/// vec![],
/// );
/// let unconstrained_triangulation = u_shape.unconstrained_triangulation().unwrap();
/// let num_triangles = unconstrained_triangulation.len();
/// assert_eq!(num_triangles, 8);
/// ```
///
fn unconstrained_triangulation(&'a self) -> TriangulationResult<Triangles<T>> {
let points = self.coords();
points
.into_iter()
.map(to_spade_point)
.try_fold(DelaunayTriangulation::<Point2<T>>::new(), |mut tris, p| {
tris.insert(p).map_err(TriangulationError::SpadeError)?;
Ok(tris)
})
.map(triangulation_to_triangles)
}
/// returns triangulation that's based on the points of the geometric object and also
/// incorporates the lines of the input geometry
///
/// The triangulation is not guaranteed to be Delaunay because of the constraint lines
///
/// This outer triangulation also contains triangles that are not included in the input
/// geometry if it wasn't convex. Here's an example:
///
/// ```text
/// ┌──────────────────┐
/// │\ __/│
/// │ \ __/ / │
/// │ \ __/ / │
/// │ \ __/ / │
/// │ \/ / │
/// │ ┌──────┐ │
/// │ /│\:::::│\ │
/// │ / │:\::::│ \ │
/// │ / │::\:::│ \ │
/// │ / │:::\::│ \ │
/// │/ │::::\:│ \│
/// └─────┘______└─────┘
/// ```
///
/// ```rust
/// use geo::TriangulateSpade;
/// use geo::{Polygon, LineString, Coord};
/// let u_shape = Polygon::new(
/// LineString::new(vec![
/// Coord { x: 0.0, y: 0.0 },
/// Coord { x: 1.0, y: 0.0 },
/// Coord { x: 1.0, y: 1.0 },
/// Coord { x: 2.0, y: 1.0 },
/// Coord { x: 2.0, y: 0.0 },
/// Coord { x: 3.0, y: 0.0 },
/// Coord { x: 3.0, y: 3.0 },
/// Coord { x: 0.0, y: 3.0 },
/// ]),
/// vec![],
/// );
/// // we use the default [`SpadeTriangulationConfig`] here
/// let constrained_outer_triangulation =
/// u_shape.constrained_outer_triangulation(Default::default()).unwrap();
/// let num_triangles = constrained_outer_triangulation.len();
/// assert_eq!(num_triangles, 8);
/// ```
///
/// The outer triangulation of the top down U-shape contains extra triangles marked
/// with ":". If you want to exclude those, take a look at `constrained_triangulation`
fn constrained_outer_triangulation(
&'a self,
config: SpadeTriangulationConfig<T>,
) -> TriangulationResult<Triangles<T>> {
let lines = self.lines();
let lines = Self::cleanup_lines(lines, config.snap_radius)?;
lines
.into_iter()
.map(to_spade_line)
.try_fold(
ConstrainedDelaunayTriangulation::<Point2<T>>::new(),
|mut cdt, [start, end]| {
let start = cdt.insert(start).map_err(TriangulationError::SpadeError)?;
let end = cdt.insert(end).map_err(TriangulationError::SpadeError)?;
// safety check (to prevent panic) whether we can add the line
if !cdt.can_add_constraint(start, end) {
return Err(TriangulationError::ConstraintFailure);
}
cdt.add_constraint(start, end);
Ok(cdt)
},
)
.map(triangulation_to_triangles)
}
/// returns triangulation that's based on the points of the geometric object and also
/// incorporates the lines of the input geometry
///
/// The triangulation is not guaranteed to be Delaunay because of the constraint lines
///
/// This triangulation only contains triangles that are included in the input geometry.
/// Here's an example:
///
/// ```text
/// ┌──────────────────┐
/// │\ __/│
/// │ \ __/ / │
/// │ \ __/ / │
/// │ \ __/ / │
/// │ \/ / │
/// │ ┌──────┐ │
/// │ /│ │\ │
/// │ / │ │ \ │
/// │ / │ │ \ │
/// │ / │ │ \ │
/// │/ │ │ \│
/// └─────┘ └─────┘
/// ```
///
/// ```rust
/// use geo::TriangulateSpade;
/// use geo::{Polygon, LineString, Coord};
/// let u_shape = Polygon::new(
/// LineString::new(vec![
/// Coord { x: 0.0, y: 0.0 },
/// Coord { x: 1.0, y: 0.0 },
/// Coord { x: 1.0, y: 1.0 },
/// Coord { x: 2.0, y: 1.0 },
/// Coord { x: 2.0, y: 0.0 },
/// Coord { x: 3.0, y: 0.0 },
/// Coord { x: 3.0, y: 3.0 },
/// Coord { x: 0.0, y: 3.0 },
/// ]),
/// vec![],
/// );
/// // we use the default [`SpadeTriangulationConfig`] here
/// let constrained_triangulation = u_shape.constrained_triangulation(Default::default()).unwrap();
/// let num_triangles = constrained_triangulation.len();
/// assert_eq!(num_triangles, 6);
/// ```
///
/// Compared to the `constrained_outer_triangulation` it only includes the triangles
/// inside of the input geometry
fn constrained_triangulation(
&'a self,
config: SpadeTriangulationConfig<T>,
) -> TriangulationResult<Triangles<T>> {
self.constrained_outer_triangulation(config)
.map(|triangles| {
triangles
.into_iter()
.filter(|triangle| {
let center = triangle.centroid();
self.contains_point(center)
})
.collect::<Vec<_>>()
})
}
}
/// conversion from spade triangulation back to geo triangles
fn triangulation_to_triangles<T, F>(triangulation: T) -> Triangles<F>
where
T: Triangulation<Vertex = Point2<F>>,
F: SpadeTriangulationFloat,
{
triangulation
.inner_faces()
.map(|face| face.positions())
.map(|points| points.map(|p| Coord::<F> { x: p.x, y: p.y }))
.map(Triangle::from)
.collect::<Vec<_>>()
}
// ========== Triangulation trait impls ============
// everything that satisfies the requirement methods automatically implements the triangulation
impl<'a, T, G> TriangulateSpade<'a, T> for G
where
T: SpadeTriangulationFloat,
G: private::TriangulationRequirementTrait<'a, T>,
{
}
impl<'a, 'l, T, G> private::TriangulationRequirementTrait<'a, T> for G
where
'a: 'l,
T: SpadeTriangulationFloat,
G: LinesIter<'l, Scalar = T> + CoordsIter<Scalar = T> + Contains<Point<T>>,
{
fn coords(&'a self) -> private::CoordsIter<T> {
Box::new(self.coords_iter())
}
fn lines(&'a self) -> Vec<Line<T>> {
self.lines_iter().collect()
}
fn contains_point(&'a self, p: Point<T>) -> bool {
self.contains(&p)
}
}
// it would be cool to impl the trait for GS: AsRef<[G]> but I wasn't able to get this to compile
// (yet)
impl<'a, T, G> private::TriangulationRequirementTrait<'a, T> for Vec<G>
where
T: SpadeTriangulationFloat + 'a,
G: TriangulateSpade<'a, T>,
{
fn coords(&'a self) -> private::CoordsIter<T> {
Box::new(self.iter().flat_map(|g| g.coords()))
}
fn lines(&'a self) -> Vec<Line<T>> {
self.iter().flat_map(|g| g.lines()).collect::<Vec<_>>()
}
fn contains_point(&'a self, p: Point<T>) -> bool {
self.iter().any(|g| g.contains_point(p))
}
}
impl<'a, T, G> private::TriangulationRequirementTrait<'a, T> for &[G]
where
T: SpadeTriangulationFloat + 'a,
G: TriangulateSpade<'a, T>,
{
fn coords(&'a self) -> private::CoordsIter<T> {
Box::new(self.iter().flat_map(|g| g.coords()))
}
fn lines(&'a self) -> Vec<Line<T>> {
self.iter().flat_map(|g| g.lines()).collect::<Vec<_>>()
}
fn contains_point(&'a self, p: Point<T>) -> bool {
self.iter().any(|g| g.contains_point(p))
}
}
// ========== Triangulation trait impl helpers ============
fn prepare_intersection_contraint<T: SpadeTriangulationFloat>(
mut lines: Vec<Line<T>>,
mut known_points: Vec<Coord<T>>,
snap_radius: T,
) -> Result<Vec<Line<T>>, TriangulationError> {
// Rule 2 of "Power of 10" rules (NASA)
// safety net. We can't prove that the `while let` loop isn't going to run infinitely, so
// we abort after a fixed amount of iterations. In case that the iteration seems to loop
// indefinitely this check will return an Error indicating the infinite loop.
let mut loop_count = 1000;
let mut loop_check = || {
loop_count -= 1;
(loop_count != 0)
.then_some(())
.ok_or(TriangulationError::LoopTrap)
};
while let Some((indices, intersection)) = {
let mut iter = iter_line_pairs(&lines);
iter.find_map(find_intersecting_lines_fn)
} {
loop_check()?;
let [l0, l1] = remove_lines_by_index(indices, &mut lines);
let new_lines = split_lines([l0, l1], intersection);
let new_lines = cleanup_filter_lines(new_lines, &lines, &mut known_points, snap_radius);
lines.extend(new_lines);
}
Ok(lines)
}
/// iterates over all combinations (a,b) of lines in a vector where a != b
fn iter_line_pairs<T: SpadeTriangulationFloat>(
lines: &[Line<T>],
) -> impl Iterator<Item = [(usize, &Line<T>); 2]> {
lines.iter().enumerate().flat_map(|(idx0, line0)| {
lines
.iter()
.enumerate()
.filter(move |(idx1, line1)| *idx1 != idx0 && line0 != *line1)
.map(move |(idx1, line1)| [(idx0, line0), (idx1, line1)])
})
}
/// checks whether two lines are intersecting and if so, checks the intersection to not be ill
/// formed
///
/// returns
/// - [usize;2] : sorted indexes of lines, smaller one comes first
/// - intersection : type of intersection
fn find_intersecting_lines_fn<T: SpadeTriangulationFloat>(
[(idx0, line0), (idx1, line1)]: [(usize, &Line<T>); 2],
) -> Option<([usize; 2], LineIntersection<T>)> {
line_intersection(*line0, *line1)
.filter(|intersection| {
match intersection {
// intersection is not located in both lines
LineIntersection::SinglePoint { is_proper, .. } if !is_proper => false,
// collinear intersection is length zero line
LineIntersection::Collinear { intersection }
if intersection.start == intersection.end =>
{
false
}
_ => true,
}
})
.map(|intersection| ([idx0, idx1], intersection))
}
/// removes two lines by index in a safe way since the second index can be invalidated after
/// the first line was removed (remember `.remove(idx)` returns the element and shifts the tail
/// of the vector in direction of its start to close the gap)
fn remove_lines_by_index<T: SpadeTriangulationFloat>(
mut indices: [usize; 2],
lines: &mut Vec<Line<T>>,
) -> [Line<T>; 2] {
indices.sort();
let [idx0, idx1] = indices;
let l1 = lines.remove(idx1);
let l0 = lines.remove(idx0);
[l0, l1]
}
/// split lines based on intersection kind:
///
/// - intersection point: create 4 new lines from the existing line's endpoints to the intersection
/// point
/// - collinear: create 3 new lines (before overlap, overlap, after overlap)
fn split_lines<T: SpadeTriangulationFloat>(
[l0, l1]: [Line<T>; 2],
intersection: LineIntersection<T>,
) -> Vec<Line<T>> {
match intersection {
LineIntersection::SinglePoint { intersection, .. } => [
(l0.start, intersection),
(l0.end, intersection),
(l1.start, intersection),
(l1.end, intersection),
]
.map(|(a, b)| Line::new(a, b))
.to_vec(),
LineIntersection::Collinear { .. } => {
let mut points = [l0.start, l0.end, l1.start, l1.end];
// sort points by their coordinate values to resolve ambiguities
points.sort_by(|a, b| {
a.x.partial_cmp(&b.x)
.expect("sorting points by coordinate x failed")
.then_with(|| {
a.y.partial_cmp(&b.y)
.expect("sorting points by coordinate y failed")
})
});
// since all points are on one line we can just create new lines from consecutive
// points after sorting
points
.windows(2)
.map(|win| Line::new(win[0], win[1]))
.collect::<Vec<_>>()
}
}
}
/// new lines from the `split_lines` function may contain a variety of ill formed lines, this
/// function cleans all of these cases up
fn cleanup_filter_lines<T: SpadeTriangulationFloat>(
lines_need_check: Vec<Line<T>>,
existing_lines: &[Line<T>],
known_points: &mut Vec<Coord<T>>,
snap_radius: T,
) -> Vec<Line<T>> {
lines_need_check
.into_iter()
.map(|mut line| {
line.start = snap_or_register_point(line.start, known_points, snap_radius);
line.end = snap_or_register_point(line.end, known_points, snap_radius);
line
})
.filter(|l| l.start != l.end)
.filter(|l| !existing_lines.contains(l))
.filter(|l| !existing_lines.contains(&Line::new(l.end, l.start)))
.collect::<Vec<_>>()
}
/// snap point to the nearest existing point if it's close enough
///
/// snap_radius can be configured via the third parameter of this function
fn snap_or_register_point<T: SpadeTriangulationFloat>(
point: Coord<T>,
known_points: &mut Vec<Coord<T>>,
snap_radius: T,
) -> Coord<T> {
known_points
.iter()
// find closest
.min_by(|a, b| {
a.euclidean_distance(&point)
.partial_cmp(&b.euclidean_distance(&point))
.expect("Couldn't compare coordinate distances")
})
// only snap if closest is within epsilone range
.filter(|nearest_point| nearest_point.euclidean_distance(&point) < snap_radius)
.cloned()
// otherwise register and use input point
.unwrap_or_else(|| {
known_points.push(point);
point
})
}
/// preprocesses lines so that we're less likely to hit issues when using the spade triangulation
fn preprocess_lines<T: SpadeTriangulationFloat>(
lines: Vec<Line<T>>,
snap_radius: T,
) -> (Vec<Coord<T>>, Vec<Line<T>>) {
let mut known_coords: Vec<Coord<T>> = vec![];
let capacity = lines.len();
let lines = lines
.into_iter()
.fold(Vec::with_capacity(capacity), |mut lines, mut line| {
// deduplicating:
// 1. snap coords of lines to existing coords
line.start = snap_or_register_point(line.start, &mut known_coords, snap_radius);
line.end = snap_or_register_point(line.end, &mut known_coords, snap_radius);
if
// 2. make sure line isn't degenerate (no length when start == end)
line.start != line.end
// 3. make sure line or flipped line wasn't already added
&& !lines.contains(&line)
&& !lines.contains(&Line::new(line.end, line.start))
{
lines.push(line)
}
lines
});
(known_coords, lines)
}
/// converts Line to something somewhat similar in the spade world
fn to_spade_line<T: SpadeTriangulationFloat>(line: Line<T>) -> [Point2<T>; 2] {
[to_spade_point(line.start), to_spade_point(line.end)]
}
/// converts Coord to something somewhat similar in the spade world
fn to_spade_point<T: SpadeTriangulationFloat>(coord: Coord<T>) -> Point2<T> {
Point2::new(coord.x, coord.y)
}
#[cfg(test)]
mod spade_triangulation {
use super::*;
use geo_types::*;
fn assert_num_triangles<T: SpadeTriangulationFloat>(
triangulation: &TriangulationResult<Triangles<T>>,
num: usize,
) {
assert_eq!(
triangulation
.as_ref()
.map(|tris| tris.len())
.expect("triangulation success"),
num
)
}
#[test]
fn basic_triangle_triangulates() {
let triangulation = Triangle::new(
Coord { x: 0.0, y: 0.0 },
Coord { x: 1.0, y: 0.0 },
Coord { x: 0.0, y: 1.0 },
)
.unconstrained_triangulation();
assert_num_triangles(&triangulation, 1);
}
#[test]
fn basic_rectangle_triangulates() {
let triangulation = Rect::new(Coord { x: 0.0, y: 0.0 }, Coord { x: 1.0, y: 1.0 })
.unconstrained_triangulation();
assert_num_triangles(&triangulation, 2);
}
#[test]
fn basic_polygon_triangulates() {
let triangulation = Polygon::new(
LineString::new(vec![
Coord { x: 0.0, y: 1.0 },
Coord { x: -1.0, y: 0.0 },
Coord { x: -0.5, y: -1.0 },
Coord { x: 0.5, y: -1.0 },
Coord { x: 1.0, y: 0.0 },
]),
vec![],
)
.unconstrained_triangulation();
assert_num_triangles(&triangulation, 3);
}
#[test]
fn overlapping_triangles_triangulate_unconstrained() {
let triangles = vec![
Triangle::new(
Coord { x: 0.0, y: 0.0 },
Coord { x: 2.0, y: 0.0 },
Coord { x: 0.0, y: 2.0 },
),
Triangle::new(
Coord { x: 1.0, y: 1.0 },
Coord { x: -1.0, y: 1.0 },
Coord { x: 1.0, y: -1.0 },
),
];
let unconstrained_triangulation = triangles.unconstrained_triangulation();
assert_num_triangles(&unconstrained_triangulation, 4);
}
#[test]
fn overlapping_triangles_triangulate_constrained_outer() {
let triangles = vec![
Triangle::new(
Coord { x: 0.0, y: 0.0 },
Coord { x: 2.0, y: 0.0 },
Coord { x: 0.0, y: 2.0 },
),
Triangle::new(
Coord { x: 1.0, y: 1.0 },
Coord { x: -1.0, y: 1.0 },
Coord { x: 1.0, y: -1.0 },
),
];
let constrained_outer_triangulation =
triangles.constrained_outer_triangulation(Default::default());
assert_num_triangles(&constrained_outer_triangulation, 8);
}
#[test]
fn overlapping_triangles_triangulate_constrained() {
let triangles = vec![
Triangle::new(
Coord { x: 0.0, y: 0.0 },
Coord { x: 2.0, y: 0.0 },
Coord { x: 0.0, y: 2.0 },
),
Triangle::new(
Coord { x: 1.0, y: 1.0 },
Coord { x: -1.0, y: 1.0 },
Coord { x: 1.0, y: -1.0 },
),
];
let constrained_outer_triangulation =
triangles.constrained_triangulation(Default::default());
assert_num_triangles(&constrained_outer_triangulation, 6);
}
#[test]
fn u_shaped_polygon_triangulates_unconstrained() {
let u_shape = Polygon::new(
LineString::new(vec![
Coord { x: 0.0, y: 0.0 },
Coord { x: 1.0, y: 0.0 },
Coord { x: 1.0, y: 1.0 },
Coord { x: 2.0, y: 1.0 },
Coord { x: 2.0, y: 0.0 },
Coord { x: 3.0, y: 0.0 },
Coord { x: 3.0, y: 3.0 },
Coord { x: 0.0, y: 3.0 },
]),
vec![],
);
let unconstrained_triangulation = u_shape.unconstrained_triangulation();
assert_num_triangles(&unconstrained_triangulation, 8);
}
#[test]
fn u_shaped_polygon_triangulates_constrained_outer() {
let u_shape = Polygon::new(
LineString::new(vec![
Coord { x: 0.0, y: 0.0 },
Coord { x: 1.0, y: 0.0 },
Coord { x: 1.0, y: 1.0 },
Coord { x: 2.0, y: 1.0 },
Coord { x: 2.0, y: 0.0 },
Coord { x: 3.0, y: 0.0 },
Coord { x: 3.0, y: 3.0 },
Coord { x: 0.0, y: 3.0 },
]),
vec![],
);
let constrained_outer_triangulation =
u_shape.constrained_outer_triangulation(Default::default());
assert_num_triangles(&constrained_outer_triangulation, 8);
}
#[test]
fn u_shaped_polygon_triangulates_constrained_inner() {
let u_shape = Polygon::new(
LineString::new(vec![
Coord { x: 0.0, y: 0.0 },
Coord { x: 1.0, y: 0.0 },
Coord { x: 1.0, y: 1.0 },
Coord { x: 2.0, y: 1.0 },
Coord { x: 2.0, y: 0.0 },
Coord { x: 3.0, y: 0.0 },
Coord { x: 3.0, y: 3.0 },
Coord { x: 0.0, y: 3.0 },
]),
vec![],
);
let constrained_triangulation = u_shape.constrained_triangulation(Default::default());
assert_num_triangles(&constrained_triangulation, 6);
}
#[test]
fn various_snap_radius_works() {
let u_shape = Polygon::new(
LineString::new(vec![
Coord { x: 0.0, y: 0.0 },
Coord { x: 1.0, y: 0.0 },
Coord { x: 1.0, y: 1.0 },
Coord { x: 2.0, y: 1.0 },
Coord { x: 2.0, y: 0.0 },
Coord { x: 3.0, y: 0.0 },
Coord { x: 3.0, y: 3.0 },
Coord { x: 0.0, y: 3.0 },
]),
vec![],
);
for snap_with in (1..6).map(|pow| 0.1_f64.powi(pow)) {
let constrained_triangulation =
u_shape.constrained_triangulation(SpadeTriangulationConfig {
snap_radius: snap_with,
});
assert_num_triangles(&constrained_triangulation, 6);
}
}
}