Geometry Boost List: Re: [geometry] Change boost polygon / ring orientation

Subject: Re: [geometry] Change boost polygon / ring orientation
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2013-09-13 16:48:26

Hi,

Hunk wrote:
> Hello,
>
> i defined on my program that a polygon is CCW and holes inside the polygon
> are CW. But not i'm using boost for area calculation and clipping
> operatoren.
>
> My problem is that i use boost::geometry::correct everytime i use a boost
> algorithm.
>
> It is possible to tell boost that my polygon is CCW so i don't have to use
> correct?
>
> Or it's the better solution that i change my orientation?

If you're using boost::geometry::model::polygon and 
boost::geometry::model::ring check out the template parameters:

http://www.boost.org/doc/libs/1_54_0/libs/geometry/doc/html/geometry/reference/models/model_polygon.html
http://www.boost.org/doc/libs/1_54_0/libs/geometry/doc/html/geometry/reference/models/model_ring.html

As you can see by default both polygons and rings are expected to be CW 
and closed (the first point should be repeated at the end of the 
container). Use template parameters which suits your needs.

Regards,
Adam