Possible oversight?

[gregmulvihill]

I was studying your code to better understand Delaunay triangulation, and I found something puzzling.

https://github.com/jonghough/Voronoi-jx/blob/master/Voronoi-jx/VoronoiGenerator.cs#L358

The second half of the if statement, "he.GetTarget().Y() >= he.GetTarget().Y()", looks like it could be a mistake or maybe not needed?

Thank you for any insight you can offer.

[jonghough]

Thanks for pointing this out. You are correct, this is an issue, but rather than being unnecessary, the current if-clause is insufficient.
The whole point of the if-clause was to only use half the half-edges, because otherwise we're duplicating lines in the Delaunay graph, but in some cases the condition

(he.GetTarget().X() >= he.Twin().GetTarget().X() && he.GetTarget().Y() >= he.Twin().GetTarget().Y()

will not add any DelaunayEdges. e.g. Two points on the plane, P1= (98, 100) and P2 = (100, 200)
becaus eneither half-edge matches the above condition.
But then again, the condition

(he.GetTarget().X() >= he.Twin().GetTarget().X()

will not add any DelaunayEdges if P1 and P2 are (100,100), and (200,100).

So, I actually need a better condition to check. I don't think it is a hard problem to solve, but I don't have time today. And worst case, just forget the if condition and draw both half-edges.

Thanks for bringing this up though, I hadn't noticed it.