CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

The kernel used does not have exact constructions.
Try again with CGAL::Exact_predicates_exact_constructions_kernel

Sebastien.

On 09/12/2016 12:00 PM, Efi Fogel wrote:
> It would easier if you just send the code and the input polygon.
> This way we can quickly try to reproduce the problem.
>
>     ____  _        ____             _
>    /_____/_) o    /__________  __  //
>   (____ (   (    (    (_/ (_/-(-'_(/
>                           _/
>
>
>
> On Mon, Sep 12, 2016 at 1:03 AM, Christopher Mitchell 
> <
> <mailto:>>
>  wrote:
>
>     Thanks for the quick response. The code is sufficiently trivial (ie,
>     a single if (CGAL::do_intersect(poly1, poly2)) { ... }) that I'm not
>     sure it would help. I'm using a simple loop to convert a set of
>     non-CGAL points into a Polygon_2, making sure to not duplicate the
>     starting point, as you can see from the image attached to the first
>     post. My polygons are CGAL::Polygon_2<CGAL_Kernel>, where
>     CGAL_Kernel is CGAL::Exact_predicates_inexact_constructions_kernel.
>     I hope this helps. Thanks!
>
>     On Sat, Sep 10, 2016 at 6:25 PM, Efi Fogel 
> <
>     
> <mailto:>>
>  wrote:
>
>         What number type are you using?  Better yet, could you share the
>         code?
>
>
>         On Sep 10, 2016 18:31, "Christopher Mitchell" 
> <
>         
> <mailto:>>
>  wrote:
>
>             I'm attempting to determine if two Polygon_2s overlap in
>             anyway, ie, share any portion of their interiors, including
>             one being entirely contained by the other. In most cases
>             this works, but for a few polygon pairs, do_intersect()
>             returns false unexpectedly. I make sure (1) all polygons are
>             simple (2) all polygons are not oriented CGAL::CLOCKWISE (I
>             call .reverse_orientation() on the polys if they are
>             CGAL::CLOCKWISE), and (3) that the starting vertex is not
>             duplicated. I have attached an example of a polygon pair for
>             which do_intersect() returns false. Thanks in advance for
>             any insight; I'd be happy to provide additional information
>             as necessary.