CGAL users discussion list

[Chris Theis <>]

Hello,

My CItemsEx is the following code below. It's actually based on one of the 
provided examples.  However, I found in one of the demos that there is a 
function to calculate normals for polyhedra. If there is no other way then I 
guess I can use this one and store all my other attributes in a wrapper class 
which will then contain the actual geometry solid as a member.

//////////////////////////////////////////////////////////////////////////////////////////////////

struct CItemsEx : public CGAL::Polyhedron_items_3

// A redefined items class for the Polyhedron_3 with a refined vertex class 
that contains a 
// member for the normal vector and a refined facet with a normal vector 
instead of the 
// plane equation (this is an alternative  solution instead of using 
// Polyhedron_traits_with_normals_3).
//////////////////////////////////////////////////////////////////////////////////////////////////
{
    // wrap vertex
    template <class Refs, class Traits>
    struct Vertex_wrapper
    {
        typedef typename Traits::Point_3  Point;
        typedef typename Traits::Vector_3 Normal;
        typedef CVertexEx<Refs,
                          CGAL::Tag_true,
                          Point,
                          Normal> Vertex;
    };

    // wrap face
    template <class Refs, class Traits>
    struct Face_wrapper
    {
        typedef typename Traits::Point_3  Point;
        typedef typename Traits::Vector_3 Normal;
        typedef CFacetEx<Refs,
                         CGAL::Tag_true,
                         Point,
                         Normal> Face;
    };

    // wrap halfedge
    template <class Refs, class Traits>
    struct Halfedge_wrapper
    {
        typedef typename Traits::Vector_3 Normal;
        typedef CHalfeEdgeEx<Refs,
                            CGAL::Tag_true,
                            CGAL::Tag_true,
                            CGAL::Tag_true,
                            Normal> Halfedge;
    };
};

Thanks a lot
Chris

----------------------------------------------------------------------------------------
Chris Theis
CERN/DGS-RP - European Organization for Nuclear Research
1211 Geneva 23, Switzerland
Phone: +41 22 767 8069                    Office: 892-2A-015
e-mail: 

           www: http://www.cern.ch/theis
-----------------------------------------------------------------------------------------


-----Original Message-----
From: 

 
[mailto:]
 On Behalf Of Sebastien Loriot (GeometryFactory)
Sent: 15 February 2013 07:09
To: 

Subject: Re: [cgal-discuss] Extended polyhedra & nef_polyhedra

On 02/14/2013 05:14 PM, Chris Theis wrote:
> Hi Sebastien,
>
> my problem actually starts when I do the following:
>
> CGAL::Polyhedron_3<Kernel,CItemsEx>  TestPoly;                              
>   // CItemsEx is derived from Polyhedron_items_3 and extends vertices, 
> faces&  halfedges
> CGAL::Nef_polyhedron_3<Kernel>   TestSolid( TestPoly );
>
> as long as I use
>
> CGAL::Polyhedron_3<Kernel, CGAL::Polyhedron_items_3>  TestPoly;
>
> it's ok. I found that the constructor of nef-polyhedra accepts only 
> standard Polyhedron_3 objects without an extended items classifier. I 
> wanted to use the extended items in order to have a convenient way to 
> calculate and store normals for vertices, faces&  halfedges as shown in one 
> of the examples.
>
Could I see what is CItemEx?

> In principle I do not necessarily need nef-polyhedra if there is another 
> convenient way to do intersections, differences and unions of Polyhedron_3 
> objects. By definition all of my polyhedra should be closed. The only other 
> two requirements that I have is that I have to test if a point is included 
> in my polyhedron (and nef-polys provide a nice way to do this) and an 
> intersection query for rays.
>
> So if there is a different way to achieve this without using nef-polys then 
> I'll also be glad to give it a try.

You can use the AABB_tree for those tasks.
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/AABB_tree/Chapter_main.html

Sebastien.

>
> I'm completely new to CGAL so I'm grateful for any information!
>
> Cheers
> Chris
>
>
> -----Original Message-----
> From: 
> 
>  
> [mailto:]
>  On Behalf Of Sebastien Loriot 
> (GeometryFactory)
> Sent: 14 February 2013 17:01
> To: 
> 
> Subject: Re: [cgal-discuss] Extended polyhedra&  nef_polyhedra
>
> Do you have a minimal example showing the issue?
>
> Depending on what you need, you might be interested by the 
> corefinement plugin in the Polyhedron demo that performs boolean 
> operations on Polyhedra directly (select the two polyhedra in the A/B 
> column). The constraint is that the intersection polylines between the 
> polyhedra are closed (including the boundaries)
>
> Sebastien.
>
> On 02/14/2013 03:36 PM, Chris Theis wrote:
>> Hello,
>>
>> I'm currently trying to implement a module which needs to perform 
>> boolean operations on polyhedra.
>> In general I'm using a class which is derived from CGAL::Polyhedron_3 
>> for managing my solids and for the boolean ops I would like to 
>> convert the polyhedra to nef_polyhedra and then back.
>>
>> If I do something like this:
>>
>>     CSGPolyhedron<Kernel, CGAL::Polyhedron_items_3>   TestPoly;
>>     CGAL::Nef_polyhedron_3<Kernel>   TestSolid( TestPoly );
>>
>> then the compiler is happy. However, I have extended my polyhedron 
>> items so my actual conversion would look like:
>>
>>     CSGPolyhedron<Kernel, CItemsEx>   TestPoly;
>>     CGAL::Nef_polyhedron_3<Kernel>   TestSolid( TestPoly );
>>
>> CItemsEx is derived from CGAL::Polyhedron_items_3 and handles the
>> information for vertex&   face normals. However, when I'm using my
>> extended items then the compiler starts complaining:
>>
>> snc_structure.h(174): error C2903: 'Halffacet' : symbol is neither a 
>> class template nor a function template ....and many more error 
>> messages
>>
>> I could trace this problem back to the use of the extended items. In 
>> principle I would not need the extended functionality within the nef 
>> polyhedra. But I don't know how to do the conversion of my extended 
>> polyhedron to the nef_polyhedron. The available constructors do not 
>> seem to work.
>>
>> Is there any other way to do this? I'd greatly appreciate any hint in 
>> this direction because I would really like to keep my extended items 
>> for the polyhedra.
>>
>> Thanks a lot
>> Chris
>>
>>
>>
>>
>> --
>> View this message in context:
>> http://cgal-discuss.949826.n4.nabble.com/Extended-polyhedra-nef-polyh
>> e dra-tp4656726.html Sent from the cgal-discuss mailing list archive 
>> at Nabble.com.
>>
>
>
> --
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