[vtkusers] tessellation with maximum edge requirement

[David Thompson]

> I have poly data ( with only triangles) defined surface.
> Such triangles define desired Geometrical approximation of the  
> surface.
> But to display scalars surface require additional tessellation, so the
> maximum edge in any triangle is not higher than user specified
> absolute value.
> ...
> To achieve the goal efficiently I need an algorithm which subdivide
> some edges, but leaves some edges untouched. ...
> I am looking for  faster and easier to implement approach, probably
> based on subdivision only.
> I thought to vtkSimpleCellTessellator , but could not find the way to
> use it to achieve what I want.

Hi Alex,

You might take a look at VTK/Graphics/vtkTessellatorFilter.{h,cxx}. It  
performs recursive, edge-based subdivision based on the nonlinearity  
of some interpolated field or geometry values. If you have some other  
criterion for determining when an edge should be subdivided you can  
write a subclass of vtkDataSetEdgeSubdivisionCriterion and use the  
vtkTessellatorFilter directly by setting Subdivider to an instance  
this subclass. Otherwise you might be able to use the  
vtkStreamingTessellator class in your own filter.

	Hope this helps,
	David