CGAL users discussion list

[Stephane Tayeb <>]

Ramin H wrote:
> Thank you for responding. It's ok if the boundary is approximated but
> it looks like the algorithm does not finish it's job. I run the Mesh_3
> example with no changes to size and approximation factors.
>
> I am attaching the screen shot of the out.mesh, visualized by medit.
>
> Also, here is the .off file that defines the cube:
> ========= Begin of OFF file ========
> OFF
> 8 6 0
> 1.632993   0.000000   1.154701
> 0.000000   1.632993   1.154701
> -1.632993   0.000000   1.154701
> 0.000000  -1.632993   1.154701
> 1.632993   0.000000  -1.154701
> 0.000000   1.632993  -1.154701
> -1.632993   0.000000  -1.154701
> 0.000000  -1.632993  -1.154701
>   4  0 1 2 3
>   4  7 4 0 3
>   4  4 5 1 0
>   4  5 6 2 1
>   4  3 2 6 7
>   4  6 5 4 7
> ========= End of OFF file ========
>
> Thanks,
> -Ramin
>
> On Fri, Nov 20, 2009 at 3:49 AM, Stephane Tayeb
> <>
>  wrote:
> > Hi,
> >
> > Ramin H wrote:
> > > Hi everyone,
> > >
> > > Before I use the 3D mesh generation functionality of CGAL 3.5 over a
> > > complicated domain, I decided to use a cube as input to Mesh_3
> > > example. The mesh created in out.mesh is missing parts of the surface
> > > boundary of the cube.
> > What do you mean by missing parts please ?
> >
> > > Is it possible to mesh cubes with the 3D mesh generation functionality
> > > or they fall under "domains with sharp edges" category?
> > Yes it is a domain with sharp edges if you want the have the edges in the
> > mesh. The actual implementation is designed for smooth surfaces only.
> >
> > If you try to mesh a cube, you will only have an approximation of the edges
> > (the element size near the edges depends of the surface approximation error
> > criterion).
> >
> > > Any idea how one can possibly overcome this issue?
> > >
> > > Thank you,
> > > -Ramin

Mesh_3 polyhedral domain is designed to handle triangulated surfaces. In 
your case, you use a quadrangular definition of the surface in the off 
file. That's why you have holes in the mesh.

Please try the attached file instead of yours.

Best,
--
Stephane Tayeb
Software engineer - INRIA Sophia Antipolis
Geometrica Project-Team
OFF
8 12 0
1.632993   0.000000   1.154701
0.000000   1.632993   1.154701
-1.632993   0.000000   1.154701
0.000000  -1.632993   1.154701
1.632993   0.000000  -1.154701
0.000000   1.632993  -1.154701
-1.632993   0.000000  -1.154701
0.000000  -1.632993  -1.154701
3 0 1 2
3 0 2 3
3 7 4 0
3 7 0 3
3 4 5 1
3 4 1 0
3 5 6 2
3 5 2 1
3 3 2 6
3 3 6 7
3 6 5 4
3 6 4 7