`Ngon`-`Segment` intersection in 2D

[tomerarnon]

julia> r = Rope(Point(1, 0), Point(1, 1), Point(2, 1));

julia> q = Quadrangle(Point(0,0), Point(0, 1), Point(1, 1), Point(1, 0));

julia> intersection(q, r)
ERROR: StackOverflowError:
Stacktrace:
 [1] intersection(f::Function, g₁::Quadrangle{2, Float64}, g₂::Rope{2, Float64, Vector{Point2}})
   @ Meshes ~/.julia/packages/Meshes/w8yhV/src/intersections.jl:100
 [2] intersection(f::Function, g₁::Rope{2, Float64, Vector{Point2}}, g₂::Quadrangle{2, Float64})
   @ Meshes ~/.julia/packages/Meshes/w8yhV/src/intersections.jl:100

julia> b = Box(Point(0,0), Point(1,1));

julia> intersection(b, r)
ERROR: StackOverflowError:
Stacktrace:
 [1] intersection(f::Function, g₁::Box{2, Float64}, g₂::Rope{2, Float64, Vector{Point2}})
   @ Meshes ~/.julia/packages/Meshes/w8yhV/src/intersections.jl:100
 [2] intersection(f::Function, g₁::Rope{2, Float64, Vector{Point2}}, g₂::Box{2, Float64})
   @ Meshes ~/.julia/packages/Meshes/w8yhV/src/intersections.jl:100

Related to #644. In my application, I would like to use a Rope to represent a "path", and I would like to find intersections between that path and a number of geometries. At the moment, those are segments, ngons (probably only rectangles), and other ropes.

I guess the stackoverlow is a red herring for any missing method: https://github.com/JuliaGeometry/Meshes.jl/issues/246

[tomerarnon]

Intersections of Box/Ngon with Segment is also missing (I wanted to see whether I could process the Rope as a series of segments).

[juliohm]

In the 2D case we need a new clipping algorithm between Segment and Ngon. We can then use this algorithm in the method with a Rope and a Ngon. The Box case should fallback to the Quadrangle case with convert(Quadrangle, box).

I am busy with other projects at the moment, and won't have the time to add these implementations in the following weeks. Feel free to propose algorithms as PRs for review.

[juliohm]

Just to double check @tomerarnon, are you aware of our intersects predicate? It can check whether or not two geometries intersect without actually computing the intersection.

[tomerarnon]

Yes! intersects is great to rule out an intersection in some cases. But when one does exist, I need to get the point/s in some cases.