CGAL users discussion list

[Manuel Caroli <>]

Hui DING wrote:
> > If you are computing a Delaunay or regular Triangulation of a 
> > non-degenerate point set, then this is uniquely defined. Therefore the 
> > resulting triangulation is always the same. Even if the point set is 
> > degenerate CGAL gives you always the same triangulation.
> > If you are not computing a Delaunay or regualar triangulation then it 
> > depends on the order in which you insert the points.
> >
> > Note that the indices as written above can change of course.
> - In the example 27.6.1, it uses the Triangulation_3, I never change the 
> order of insertion, why it changes too? (sometime the number of cells is 
> 12, sometime is 11)?
There is some randomization involved in order to accelerate the algorithm.

Be aware that a triangulation of 5 points in IR^3 can consist of either 
2 or 3 tetrahedra.

I cite from the manual:
template < class InputIterator >
int     t.insert ( InputIterator first, InputIterator last)
		Inserts the points in the range [.first, last.). Returns the number of 
inserted points. Note that this function is not garanteed to insert the 
points following the order of InputIterator.
Precondition:   The value_type of first and last is Point.


best

Manuel