[vtkusers] pb w. Delaunay on multiple polygons

[Will Schroeder]

Hi Melvin-

At 06:45 PM 4/22/2002 +0200, Melvin Hadasht wrote:
>Hi,
>
>I have a vtkCellArray containing two or more polygons that I wish to
>triangulate using vtkDelaunay (for the constrained triangulation
>ability). On a test case of two regular polygons one above the other,
>the triangulations succeeds for both polygons only if the number of the
>sides of the polygon are less than 8. Above this limit, the second
>created polygon is not correctly triangulated:


If I am reading your script properly, you are using vtkDelaunay2D 
incorrectly. The first polygon defines the outer boundary of the polygons; 
subsequent polygons in the input define holes in the polygon. You are 
placing both polygons in the same source polydata, which doesn't make 
sense. Instead, you should put each polygon in a separate polydata (include 
holes as additional polygons) and triangulate with a separate 
vtkDelaunay2D. Or equivalently, set up a pipeline of vtkPolyData and 
vtkDelaunay2D, load the polygon (and any holes in the polygon) in the 
vtkPolyData, execute the pipeline, save the output, and then repeat the 
process. You may have to invoke Modified() on the vtkPolyData every time 
you stuff new data into it.

Will



William J. Schroeder, Ph.D.
Kitware, Inc.
469 Clifton Corporate Parkway
Clifton Park, NY 12065
will.schroeder at kitware.com
1-518-371-3971 x102 (phone)
1-518-371-3971 (fax)