CGAL users discussion list

[Monique Teillaud <>]

Hi Daniel

I probably read your messages too quickly, I had thought the flip was 
working but that you were getting an invalid triangulation.
I had not understood it was a precondition that was telling you this, 
otherwise I would have given the answer (I even checked in the code that 
the precondition was actually coded...)
good you finally found the solution!

Daniel Duque Campayo wrote:
> Hello,
>
> For the record, I have found the answer to my question.
>
> >             T.flip(f,indx);
>
> You cannot flip just any pair of adjacent triangles: they have to form a 
> convex object!
>
> This is precisely what the precondition error was telling me (as soon as I 
> realized "orientation" meant position of a point relative to a line, not 
> triangle orientation). This makes sense, since for my terrain such a 
> forbidden flip would create a two-valued (folded) terrain, not quite what one 
> wants.
>
> Best,
>
> Daniel