make line intersection changes not breaking

Author: ffreyer

src/lines.jl

@@ -63,11 +63,21 @@ end
     self_intersections(points::AbstractVector{<:Point})
 
 Finds all self intersections of in a continuous line described by `points`.
+Returns a Vector of indices where each pair `v[2i], v[2i+1]` refers two
+intersecting line segments by their first point, and a Vector of intersection
+points.
 
 Note that if two points are the same, they will generate a self intersection
-unless they are the first and last point or part of consecutive segments.
+unless they are consecutive segments. (The first and last point are assumed to
+be shared between the first and last segment.)
 """
 function self_intersections(points::AbstractVector{<:VecTypes{D, T}}) where {D, T}
+    ti, sections = _self_intersections(points)
+    # convert array of tuples to flat array
+    return [x for t in ti for x in t], sections
+end
+
+function _self_intersections(points::AbstractVector{<:VecTypes{D, T}}) where {D, T}
     sections = similar(points, 0)
     intersections = Tuple{Int, Int}[]
 
@@ -98,7 +108,7 @@ Splits polygon `points` into it's self intersecting parts. Only 1 intersection
 is handled right now.
 """
 function split_intersections(points::AbstractVector{<:VecTypes{N, T}}) where {N, T}
-    intersections, sections = self_intersections(points)
+    intersections, sections = _self_intersections(points)
     return if isempty(intersections)
         return [points]
     elseif length(intersections) == 1 && length(sections) == 1

test/runtests.jl

@@ -285,18 +285,24 @@ end
     @test collect(GeometryBasics.consecutive_pairs(ps)) == collect(zip(ps[1:end-1], ps[2:end]))
 
     ps = Point2f[(0,0), (1,0), (0,1), (1,2), (0,2), (1,1), (0,0)]
-    idxs, ips = self_intersections(ps)
+    idxs, ips = _self_intersections(ps)
     @test idxs == [(2, 6), (3, 5)]
     @test ips == [Point2f(0.5), Point2f(0.5, 1.5)]
+    idxs2, ips2 = self_intersections(ps)
+    @test ips2 == ips
+    @test idxs2 == [2, 6, 3, 5]
 
     ps = [Point2f(cos(x), sin(x)) for x in 0:4pi/5:4pi+0.1]
-    idxs, ips = self_intersections(ps)
+    idxs, ips = _self_intersections(ps)
     @test idxs == [(1, 3), (1, 4), (2, 4), (2, 5), (3, 5)]
     @test all(ips .≈ Point2f[(0.30901694, 0.2245140), (-0.118034005, 0.36327127), (-0.38196602, 0), (-0.118033946, -0.3632713), (0.309017, -0.22451389)])
+    idxs2, ips2 = self_intersections(ps)
+    @test ips2 == ips
+    @test idxs2 == [1, 3, 1, 4, 2, 4, 2, 5, 3, 5]
 
     @test_throws ErrorException split_intersections(ps)
     ps = Point2f[(0,0), (1,0), (0,1), (1,1), (0, 0)]
-    idxs, ips = self_intersections(ps)
+    idxs, ips = _self_intersections(ps)
     sps = split_intersections(ps)
     @test sps[1] == [ps[3], ps[4], ips[1]]
     @test sps[2] == [ps[5], ps[1], ps[2], ips[1]]