Geometry Boost List: [ggl] Quick question about bg::difference

Subject: [ggl] Quick question about bg::difference
From: Barend Gehrels (barend)
Date: 2011-10-25 20:15:52

Hi,

I believe that the difference problem you reported is fixed now. I'm 
avoiding now the reversal of arguments (both in difference and in 
sym_difference, which calls difference). It initially caused failing of 
one (of many) unit tests, but it appeared that that test was wrong. So 
thanks again for the report.

I added unit tests for your cases.

I just also tested your additional case below and it is now going OK as 
well, fixed by the earlier fix.

I added also a unit test for this case. See the image below.

On 25-10-2011 20:10, V D wrote:
> Hi Barend,
>
> Just a follow-up on this issue.
>
> Let's consider the case where MP and P are not disjoint.
> bg::difference(MP, P) will lose any polygon in MP that is disjoint with P.
>
>
> Example with images:
>
> Say the MP is the 2 squares below and P is the blue-ish rectangle.
>
>
>
>
> The output should be something similar to:
>
>
> But the actual output will be:
>
>
>

Images of P-Q and Q-P (I had this already so used other colors, purple 
is the output)

BTW all these kind of images are created by the SVG extension which we 
think of moving to non-extension.

Regards, Barend

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