CGAL users discussion list

[Chris Marsh <>]

Hi,

I've never used the Qt functionality of CGAL, but I think you need to use just CGAL::draw(tri), as per

https://doc.cgal.org/latest/Triangulation_2/Triangulation_2_2draw_triangulation_2_8cpp-example.html

If I add

#include <CGAL/draw_triangulation_2.h>

<.. snip ..>

// Painter tool.

CGAL::draw (tri);

It compiles successfully. However, I get:

./src/bin/triangulation
Number of vertices = 3
Number of faces = 2
Impossible to draw because CGAL_USE_BASIC_VIEWER is not defined.

I'm on MacOS and my Qt library through brew causes me nothing but problems, so it might be related to that. Otherwise this might solve it for you (didn't for me)

https://stackoverflow.com/questions/53150670/impossible-to-draw-because-cgal-use-basic-viewer-is-not-defined

Everything I've read over the years suggests the viz in cgal is for quick and dirty visualization.

e.g.,

http://cgal-discuss.949826.n4.nabble.com/Tutorial-for-visualisation-in-CGAL-using-QT-td4656057.html

Depending on what your needs are, you might want to consider writing to a format that is easily visualized in another software. If you're interested in visualizing simulation output, might I suggest writing to a Paraview (paraview.org) format (vtu)? This approach has treated me very well. It's pretty straightforward format to write to (VTK library does the hard part), and Paraview is immensely useful for visualizing simulation outputs  and exploring a mesh. I can send you a paraview file that is an exported CGAL mesh if you're interested.

Cheers

Chris Marsh
PhD Candidate
chrismarsh.ca

On Tue, 13 Nov 2018 at 10:06, Yoann LE BARS <> wrote:

Hello everybody out there!

        Well, I think I have been able to create a “CGAl::Triangulation_2” with
a given existing mesh (see the code attached to this message). Now, I am
still trying to draw it using “TriangulationGraphicsItem”, but I still
obtain a quite long compiling error. Here is the first line of error I get:

main.cpp:70:59: error: no matching function for call to
‘CGAL::Qt::TriangulationGraphicsItem<CGAL::Triangulation_2<CGAL::Epick,
CGAL::Triangulation_data_structure_2<CGAL::Triangulation_vertex_base_2<CGAL::Projection_traits_xy_3<CGAL::Epick>
>,
CGAL::Constrained_triangulation_face_base_2<CGAL::Projection_traits_xy_3<CGAL::Epick>
> > > >::TriangulationGraphicsItem(Triangulation&)’
  CGAL::Qt::TriangulationGraphicsItem<Triangulation> p (tri);
                                                           ^

        The code attached is a minimal complete example, which shows how I try
to draw a mesh. Now, still, I cannot find a way to draw a mesh. Is there
any example available on how to draw a “Triangulation_2” using
“TriangulationGraphicsItem” anywhere? I cannot find any.

        Best regards.

--
Yoann LE BARS
http://le-bars.net/yoann
*Diaspora :

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