Geometry Boost List: [ggl] Re: Problems with the difference between two polygons

Subject: [ggl] Re: Problems with the difference between two polygons
From: Barend Gehrels (barend)
Date: 2011-08-08 01:22:32

>
> I've rearranged the vertices above (see below) since Ggl's are 
> counter-clockwise to the other two, and also removed duplicate 
> vertices and I get the following ...
>
> Gtl:
> 51600,0
> 25800,-44686
> 25799,-44686
> 26449,-45812
> 26450,-45812
> 52900,0
>
> Ggl:
> 51600,0
> 25800,-44686
> 25799.615099925981,-44686
> 26449.711324944485,-45812
> 26450,-45812
> 52900,0
>
> Clipper:
> 51600,0
> 25800,-44686
> 26450,-45812
> 52900,0
>
> You can see that if the vertices returned by Ggl are then rounded 
> they'll produce duplicate vertices. 

Why should you do that? Round them and then consider them as duplicate? 
If they would be duplicate (before rounding), they would not be included 
(since this is solved).

>
> Thanks for all your efforts in doing these tests. The results are very 
> interesting. Would you consider adding one more test that benchmarked 
> self-intersecting polygons too?

In the meantime I've seen why it currently can be slow, within GGL, and 
it will be solved (regardless if the test will be there, or not, of course).

Regards, Barend