CGAL users discussion list

[Stefan Schirra <>]

Hi,

Rafael Roberto wrote:

> I have some points from a cube. They are very well distributed so that 
> every face have 100 points. But, when I call CGAL::convex_hull some 
> points are connected to the others. Some faces have only two triangle, 
> others have 5 or 6, but it never generate a convex hull with all the 
> points triangulated (attached we have one of its faces projected).

I guess, you use a incremental CGAL algorithm that processes the points 
one by one. Whenever a point to be processed is outside of the current 
hull, it is a new vertex and hence connected to the vertices of the 
ridges of the visible part of the current hull, in your terminology, "it 
is triangulated"; If the point is inside or on the boundary of the 
current hull, nothing happens.

> Does anybody know if there is any way to use this CGAL function and all 
> points be triangulated?

Well, you need to process the points in such a way that points are 
always outside the present hull, for example, row by row per face. This 
works, unless the CGAL algorithm permutes the points internally in order 
to guarantee good expected worst case behavior. I don't know whether a 
random permutation is applied, I guess not.

best regards

        Stefan