CGAL users discussion list

[Pratyush Pranav <>]

Hi Monique,

I have some further questions on this which I wonder you might be able to 
give me some clues on. I will also mark this for the agal-discuss forum.

So, basically I have pixels on the surface of a sphere (s^2), and there are 
function values given on the pixels.

My idea is to construct a 2D triangulation of these points on the surface, 
which you pointed out is the convex hull of the triangulation of these points 
in 3D. Additionally, it should probably be inherited from “ 
vertex_base_with_info” because there is additional data on each vertex.

Now, assuming this is my simplicial complex, I must output the simplifies 
(vertices, edges and facets in a particular order) : for each vertex (which 
have priori been arranged in ascending  order in a vector according to the 
values specified on the vertex), i must look at the incident edges and 
facets, and output only those edges and facets whose vertices have value less 
than the value of the vertex on which i am currently checking the incidence.

With just a triangulation in 3D it is easy to do this, because there are edge 
and facet circulators/iteratiors defined for the incident edges and facets on 
a vertex. But I cannot do this with the whole triangulation, because i am 
interested in the edges and facets that belong only to the convex hull.

One solution is to check for the edges and facets if they belong to the 
convex hull before outputting them. Is there a function in the triangulation 
that checks whether the given simplifies belong to the convex hull?

Another possibility is that I explicitly construct the convex hull from the 
triangulation, and work only with that. In that case, are there iterators 
defined for vertices, edges and facets of the convex hull, for me to be able 
to make an operation like with the triangulation above?

regards

Pratyush

P.S:  I can add a working code that gives me the desired output for the 
triangulation of these points in 3D, and i would like to do the same for the 
convex hull only of these points.