dpuyda / triclipper Goto Github PK

Hello! Thank you for the fantastic writeup on how the Vatti algorithm works.
I tried using the library, but am getting some weird results.

Here is an attempt at taking the union of two triangles:

clipper.AddTriangle({0, 0}, {0, 50}, {100, 0});
clipper.AddTriangle({0, 0}, {100, 50}, {100, 0});
clipper.Execute<OperationType::kUnion>();

This gives me:

2 polygon(s):

Polygon 0:
(0, 0)
(0, 50)
(50, 25)
(100, 0)

Polygon 1:
(100, 0)
(50, 25)
(100, 50)

when I expected the union to only be a single polygon.

Also, when I tried a more complicated example that was supposed to be the union of two boxes, I get two triangles that make up the bottom bit of the region:

clipper.AddTriangle({0, 0}, {100, 0}, {100, 100});
clipper.AddTriangle({0, 0}, {100, 100}, {0, 100});
clipper.AddTriangle({50, 50}, {150, 50}, {150, 150});
clipper.AddTriangle({50, 50}, {150, 150}, {50, 150});
clipper.Execute<OperationType::kUnion>();

2 polygon(s):

Polygon 0:
(0, 0)
(0, 50)
(50, 25)
(100, 0)

Polygon 1:
(100, 0)
(50, 25)
(100, 50)