# [vtkusers] Making True Constrained Delaunay

Amy Squillacote amy.squillacote at kitware.com
Thu Jun 15 08:09:05 EDT 2006

```Hi Janko,

I'm copying this back to the users list so other people can help answer
your question and so that the discussion will be archived (so other
people can see it if they have the same question later).

- Amy

Janko Jerinic wrote:
> Hi Amy,
>
> Well, the hole should exist and be triangulated so that the edges of
> the polyline
> that surround the "hole" (constraint) are preserved. Furthermore,
> supplying a
> single edge or a number of unconnected edges (that do not form a clockwise
> oriented polygon inside the triangulation perimeter) doesn't work, but
> not in
> the way that the triangles do not comply with the constraints, in fact
> no triangles
> are generated :) So that may lead us to conclude that vtkDelaunay2d
> does NOT do
>
> Janko Jerinic
>
>
> 2006/6/14, Amy Squillacote <amy.squillacote at kitware.com
> <mailto:amy.squillacote at kitware.com>>:
>
>     Hi Janko,
>
>     Are you saying that you want the hole to exist after triangulation or
>     that you do not want the hole to exist ( i.e., that it should be
>     triangulated)?
>
>     - Amy
>
>     Janko Jerinic wrote:
>     > Hi,
>     >
>     > Is it possible to make a proper constrained delaunay triangulation
>     > using VTK classes? The essence
>     > of the constraints is that we can specify edges to remain after the
>     > triangulation, all I can do with
>     > vtkDelaunay2d is make a clockwise closed polyline constraint and
>     > segments of the polyline do
>     > remain, but the inside of the polyline is a Hole, its not
>     triangulated
>     > at all. Is there any way of
>     > applying several unconnected line constraints and hope that the
>     > triangulation would use them properly?
>     >
>     > Thx,
>     > Janko Jerinic
>     >
>     ------------------------------------------------------------------------
>
>     >
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