Re: [boost] [GGL][Polygon][Union] Union returns hole (inner ring) of the expected result as the output polygon (outer ring)

Subject: Re: [boost] [GGL][Polygon][Union] Union returns hole (inner ring) of the expected result as the output polygon (outer ring)
From: Barend Gehrels (barend_at_[hidden])
Date: 2010-01-27 13:16:53

Hi Helal ,

This was not a known problem, I will investigate this, and answer you 
tomorrow or Friday (I cannot start immediately...).

>
>
> The Union of a rectangle with a hexagonal hole and a triangle 
> intersecting the first polygon
>
> *****************************
> *****************************
> *****************************
> ********            *********
> *******              **X*****
> ******               XXX*****
> *****               XXX******
> ****               XX   *****
> *****                  ******
> ******                *******
> *******              ********
> ********            *********
> *****************************
> *****************************
> *****************************
>
> returns this polygon, instead of the correct result.
>
>         ++++++++++++
>        ++++++++++++++
>       +++++++++++++++
>      +++++++++++++++
>     +++++++++++++++  +++
>      ++++++++++++++++++
>       ++++++++++++++++
>        ++++++++++++++
>         ++++++++++++
>
> You can use the code bellow to generate the case and some PPM images. 
> You may use a WSQ Viewer to see the polygons.
>
> Please let me know any workaround or anything thats I am missing.

The problem is completely clear, thanks for the useful pictures and 
source code.

Regards, Barend