Geometry Boost List: [geometry] Strange behavior at difference algorithm

Subject: [geometry] Strange behavior at difference algorithm
From: Franz Alt (franz.s.alt_at_[hidden])
Date: 2015-03-17 09:17:16

Hi,

I've written a simple test program using the difference algorithm of
geometry. I want to build the difference of two simple rectangle polygons
(see attachment input.png).

Regardless of whether I subtract polygon A from B or I subtract B from A I
got very strange output polygons (see attachments output1.png and
output2.png).

I've tested with Boost 1.56, 1.57 and the beta of 1.58. All versions lead
to the same results.

Does someone know what is wrong here?

Thanks

Franz