CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 07/04/2014 06:12 PM, Oliver Gloth wrote:
> Hello,
>
> I am fairly new to CGAL and managed to use it in order to project a
> point in 3D space onto the closest location on a triangulated surface.
> The background of this is the generation of a computational mesh for CFD
> (open-source tool enGrid, see http://engits.eu/engrid).
>
> Computing the closest point in terms of an (x, y, z) triple works and
> you can find the code here:
> https://github.com/enGits/engrid/blob/new_concept/src/libengrid/cgaltricadinterface.h
> https://github.com/enGits/engrid/blob/new_concept/src/libengrid/cgaltricadinterface.cpp
>
> What I would also like to have is the index of the triangle on which the
> projected point is. With this information we would like to compute
> additional properties like, for example, local curvature or the local
> normal vector of the surface.
>
> Is this possible? If yes, does somebody have a small piece of example
> code which illustrates how to do this?

If you use the function closest_point_and_primitive, you'll be able
to get the iterator of the triangle and convert it to an index.

Sebastien.

> Best regards,
> Oliver
>
> Dr.-Ing. Oliver Gloth (managing partner)
> phone: +49 (0)7671-992-5110, fax: -222-9689, mobile +49 (0)173-317-3698
>
> enGits GmbH, http://engits.eu, Todtnau, AG Freiburg HRB 700491
> Geschaeftsfuehrer/managing partner: Dr. Oliver Gloth