CGAL users discussion list

[Qianqian Fang <>]

hi

I was able to compile the mesh-simplification example at
example/Surface_mesh_simplification/edge_collapse_enriched_polyhedron.cpp
with the help from the list this morning.

Here I got another quick question. I am trying to simplify a surface mesh.
This mesh has multiple borders. For example, one of the border is marked
as green dots on this plot:

http://nmr.mgh.harvard.edu/~fangq/temp/oldmesh.png

after the simplification , I found that the border nodes were moved, for 
the above example,
a plot of the new mesh is shown at

http://nmr.mgh.harvard.edu/~fangq/temp/newmesh.png

I found that the number of the border nodes are identical before and
after the simplification, however, their positions were slightly moved,
(the original border nodes are plotted as green dots, the new border
nodes are marked as blue circles)

For my specific application, I want to keep (fix) all border nodes, so 
that before and after
the simplification, these nodes are identical.

I searched the source code in CGAL and found "EdgeIsBorderMap" for the 
simplification units,
I am not entirely sure whether that is related to my purpose. If it is 
not, is there another
flag that I can set in edge_collapse_enriched_polyhedron.cpp so that the 
simplification only
touches the internal edges?

thank you very much

Qianqian