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- From: "Sebastien Loriot (GeometryFactory)" <>
- To:
- Subject: Re: [cgal-discuss] How to get Contour of the intersection plane and polyhedron
- Date: Tue, 17 Jul 2012 08:52:09 +0200
On 07/17/2012 02:50 AM, 马良 wrote:
> Hello Sebastien Loriot,
> Thank you replay.
> Yes, I test the example of AABB tree demo. There is no problem to
> caculate intersections between a plane and polyhedron.
> But, the results of intersections are many Segment object. I debug those
> segments, and find that those intersetion segments is no end to end
I guess because you are using a kernel with inexact constructions.
Try with Exact_predicates_inexact_constructions_kernel for example.
http://www.cgal.org/FAQ.html#inexact_NT
Sebastien.
> Sequentially.
> I want to find loops (segment attach together sequentially).
>
> My question:How to constitute "Loops" using those segments??
>
>
> 2012/7/13 Sebastien Loriot (GeometryFactory)
> <
>
> <mailto:>>
>
> If you run the AABB_tree demo, you can open an off file (simple to
> create from stl), then
> run Algorithms ->cut plane -> intersection.
>
> You can extract the code from the demo (file Scene.cpp function
> cut_segment_plane).
>
> The principal is simple: you create an aabb_tree using the facets of the
> mesh, and you
> create all intersections with you plane.
>
> See:
>
> http://www.cgal.org/Manual/latest/doc_html/cgal_manual/AABB_tree_ref/Class_AABB_tree.html
>
> Sebastien.
>
> On 07/13/2012 03:29 AM, 马良 wrote:
> > Hi
> > I read a STL-file (a kind of file using in RapidPrototyping, a
> triangle
> > in STL is composed of 3-Point and normal). And I create a Polyhedron
> > like a following.
> > Polyhedron P;
> > P.make_triangle(V1,V2,V3);
> > P.make_triangle(V4,V5,V6);
> > ....
> > //Then, I create AABB tree, as follows:
> > Facet_tree tree(P.facets_begin(),P.facets_end());
> > //Next, I create a plane and caculate intersections between plane and
> > polyhedron
> > Vector nor(0,0,1);
> > Point pnt(0,0,0.5);
> > Plane plane(pnt,nor);
> > tree.all_intersections(plane,std::back_inserter(Intersetions));
> > //Here, I get intersetions (Points: (X,Y,Z))
> > for( it = Intersetions.begin();it !=Intersections.end();it++)
> > {
> > if(CGAL::assign(segment,object) m_segment.push_back(segment);
> > }
> > // But, I get a lot of segments. And Here I want get contours (a
> contour
> > is composed of segments in order).
> > My question is How to constitute contours using segments. Whether
> or not
> > I must sort those segments by myself? Here is a algorithm in CGAL?
> > Thanks!
> >
> > --
> > 马良 Mr.MaLiang
> > State Key Laboratory of Solidification Processing
> > Northwestern Polytechnical University
> > Xi'an 710072, Shanxi
> > P. R. China
> > Tel/Fax:+86(29)88460520
> > Mobile:+86(0)15829297776
> > Email:
>
>
> <mailto:>
>
> <mailto:
>
> <mailto:>>
> > QQ number:394646034
> >
>
>
> --
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>
>
>
>
> --
> 马良 Mr.MaLiang
> State Key Laboratory of Solidification Processing
> Northwestern Polytechnical University
> Xi'an 710072, Shanxi
> P. R. China
> Tel/Fax:+86(29)88460520
> Mobile:+86(0)15829297776
> Email:
>
>
> <mailto:>
> QQ number:394646034
>
- [cgal-discuss] How to get Contour of the intersection plane and polyhedron, 马良, 07/13/2012
- Re: [cgal-discuss] How to get Contour of the intersection plane and polyhedron, Sebastien Loriot (GeometryFactory), 07/13/2012
- Re: [cgal-discuss] How to get Contour of the intersection plane and polyhedron, 马良, 07/17/2012
- Re: [cgal-discuss] How to get Contour of the intersection plane and polyhedron, Sebastien Loriot (GeometryFactory), 07/17/2012
- Re: [cgal-discuss] How to get Contour of the intersection plane and polyhedron, 马良, 07/17/2012
- Re: [cgal-discuss] How to get Contour of the intersection plane and polyhedron, Sebastien Loriot (GeometryFactory), 07/13/2012
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