[vtk-developers] vtkDataSetSurfaceFilter and Quadratic Cells

[Mathieu Malaterre]

Hello,

	I am currently working on the quadratic cells in VTK. And there is 
something I would like to remove. vtkDataSetSurfaceFilter currently 
allow user to pass them. The problem is that internally it tessellate 
the quadratic elements into linear primitive using the 
vtkNonLinarCell::Tessellate() function.

	Unfortunately this function does not respect diagonal choice along 
faces. Meaning that the Tessellate can either decide to split -let say- 
an hexahedron along one diagonal and then split along the other diagonal 
on the neighboor hexahedron leading to problems for the 
vtkDataSetSurfaceFilter to recognize those triangles.

	Two options:

1. Support up to 9 points as the internal entry of the hash in the 
vtkDataSetSurfaceFilter

or

2. Remove support of quad cells from vtkDataSetSurfaceFilter. Thus user 
will have to use vtkDataSetTriangleFilter first before using the 
vtkDataSetSurfaceMapper.

I would rather go for option 2 and remove support for quad cells.

Let me know if this is a problem and you would rather like option 1.

Mathieu