CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 02/04/2014 06:56 PM, 芮泽亚 wrote:
> Hi Sebastien
> What do you mean" intersection predicate "?
> It seems all the intersection tests output intersection even if the two 
> objects touch.
> After the box intersection, I may further do the triangle intersection.
> But if two triangles touch, the intersection function would always say 
> they intersect.
> In my problem, I would say they do not intersect if they touch cause the 
> optimal solution of my problem may occur when the objects touch.

An easy way to do it is to compute the intersection and check if it's an
edge or
a vertex of the triangle.

Sebastien.

> 
> Thanks:)
> Vanessa
> 
> 
> 2014-02-04 Sebastien Loriot (GeometryFactory) 
> <
>  
> <mailto:>>:
> 
>     You can use this package:
>     http://doc.cgal.org/latest/__Box_intersection_d/index.html
>     <http://doc.cgal.org/latest/Box_intersection_d/index.html>
>     and use an intersection predicate matching your need.
> 
>     Sebastien.
> 
> 
> 
>     On 02/04/2014 04:24 PM, 芮泽亚 wrote:
> 
>         Hi
>         I mean the two polyhedrons touch(share a common point, edge, or
>         face).
>         It seems when I use the function, it will output the two polyhedrons
>         intersect in this case.
>         But in my problem, this case requires to be considered no
>         intersection.
>         Can you give me some hints about how to check this case?
> 
>         Thanks for your help.
>         Vanessa
> 
> 
>         2014-02-04 Sebastien Loriot (GeometryFactory)
>         
> <
>  
> <mailto:>
>         
> <mailto:
>  
> <mailto:>>>__:
> 
> 
>              On 02/04/2014 02:27 PM, vanessa wrote:
> 
>                  Hi all
> 
>                  I'm trying to do the intersection test for two 3D
>         polyhedrons
>                  using the
>                 
>         function"CGAL::intersection_____Polyhedron_3_Polyhedron_3(____Poly1,
>                  Poly2,
>                     std::back_inserter(polylines))____;".
> 
> 
>                  It performs well.But when one polyhedron is in contact
>         to the
>                  other, the
>                  output (size of polylines) shows 1 instead of 0. Is
>         there any
>                  method to
>                  check the case that two polyhedrons are in contact?
> 
>              What do you mean by in contact?
>              IIRC, note that this function is will not report
>         intersection points.
> 
>              Sebastien.
> 
> 
> 
>                  Many thanks
>                  Vanessa
> 
> 
> 
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