Issue with polygon merging

[Etienne Dumur]

Hi,

I am having issue with polygons merging.

If a create a bunch of polygons as:

# Make a bunch of rectangles
tot = []
tot.append(np.array([[  -5., -100.],
                     [   5., -100.],
                     [   5.,  100.],
                     [  -5.,  100.]]))

tot.append(np.array([[  45., -100.],
                     [  55., -100.],
                     [  55.,  100.],
                     [  45.,  100.]]))

tot.append(np.array([[-100.,   -5.],
                     [ 100.,   -5.],
                     [ 100.,    5.],
                     [-100.,    5.]]))

tot.append(np.array([[-100.,   45.],
                     [ 100.,   45.],
                     [ 100.,   55.],
                     [-100.,   55.]]))

I obtain this:

If I "merge" the polygons to have only one left as:

# Execute the  merge
pc = pyclipr.Clipper()
pc.scaleFactor = int(1000)

pc.addPaths(tot, pyclipr.Subject)

tot = pc.execute(pyclipr.Union,
                pyclipr.FillRule.EvenOdd)

I get this:

You can remark the holes at the intersections of the polygons.
I was expected something like this:

Which is something I get by using Klayout and click on: edit -> selection -> merge

If you can help me to get the same result as with Klayout that would be really helpful.