CGAL users discussion list

[Giles Bathgate <>]

On 24 June 2011 20:49, Giles Bathgate 
<>
>What I would like to be able in to do now in addition to my original
>request is to list the halfedge vertexes in clockwize order.
>What is the easiest way to achieve this.

Well, I have managed to get the halfedges out in the correct order:

http://git.rapcad.org/cgit.cgi/rapcad/commit/?id=e39711286195eef79b6feda3bb03fe06c3d1e011
http://git.rapcad.org/cgit.cgi/rapcad/commit/?id=0a5eed8e2b1ae6f56cc8c1144c22edd4151dd415

but sometimes they are oriented clockwize, and other times counterclockwise.

This is okay, if for example I can capture the orientation within a
normal, is there an easy way
to find the normals.

Another thought is prehaps you can see a simpler way to do the whole
thing witch is to linear extrude my original polyhedron.

>Nef_polyhedron_3 consisting of a pair of non coplanar facets.
>The facets share an edge.
>For example if you have the vertices in [x,y,z] notation.

>a=[0,0,0], b=[0,10,0], c= [10,0,0], d=[10,10,2]

>and the triangles [a,b,c] and [b,d,c] they both share the edge from b to c.

and similar nef surfaces.

I did see some code somewhere writtern to achive this using HDS
modifier but I didn't understand how it worked.

Regards

Giles