CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 08/08/2017 01:15 PM, 

 wrote:
> Hi
>
> I am trying to compute the vertex normals for a surface mesh I have imported
> but I receive the compiler error "no matching function for call to sqrt()"
> when calling CGAL::Polygon_mesh_processing::compute_vertex_normals. I tried
> to use the Exact_predicates_exact_constructions_kernel_with_sqrt, but that
> does not seem to enable me to call the sqrt() function, compiling using
> Simple_cartesian<double> has no issues. I chose the exact kernel because
> ultimately I would like to do a number of boolean operations on the mesh and
> an exact kernel is recommended.
>
> What am I misunderstanding that I cannot use the kernel with sqrt to
> calculate vertex normals? Is it possible to convert the mesh from the simple
> cartesian kernel to the exact kernel after computing the normals just to
> perform the boolean operations? Is that terribly inefficient?

Which boolean operations are you talking about? Nef_3 or those through 
corefinement [1]?
For the latter a kernel with exact constructions is only needed if you
are doing consecutive operations.

Also the normal computation is not needed by Nef_3 nor the corefinement
operations.

Which CGAL version are you using? AFAIR the issue with normal
computations and EPECK were fixed a few releases back.

Sebastien.

[1] 
http://doc.cgal.org/latest/Polygon_mesh_processing/index.html#Coref_section



> Thanks,
> Jack
>
>
>
> --
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