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Chris Myers wrote:
<BLOCKQUOTE TYPE=CITE>I am working with a polyhedral dataset in 3D (from
a Voronoi tesselation).
<BR>Since I cannot explicitly represent the polyhedra in VTK (i.e., there
is
<BR>no ConvexPolyhedron cell type, unless I want to build it myself),
<BR>I am representing the polygonal facets of the polyhedra as vtkPolyData.
<P>If I cut this Polydata (with a vtkCutter, using a simple cutting
<BR>plane), I get a new PolyData instance that lies in the cut plane; this
<BR>new Polydata is essentially a set of polygons. But, because I
have
<BR>represented my polyhedral set by the polygonal facets rather than
<BR>the polyhedral cells, the output of the vtkCutter is a collection of
<BR>lines, rather than a collection of polygons. (The output is still
a
<BR>vtkPolyData instance, but all the data are defined as Lines in the
<BR>PolyData rather than as Polys.)
<P>I would like to be able to convert this vtkPolyData instance, consisting
<BR>a lines connecting vertices, to the equivalent vtkPolyData, consisting
<BR>of polygons connecting the vertices. I could obvously build this
up myself
<BR>by examining all the Lines in the vtkPolyData, but was hoping that
there
<BR>might be some sort of filter in VTK that already would accomplish that.
<P>If anyone knows of a convenient way of reorganizing this PolyData,
<BR>I'd appreciate hearing about it.
<P>(Also, if anyone has developed any better strategies for dealing with
<BR>arbitrary convex polyhedra in VTK, I'd like to hear about those too.)
<P>Thanks,
<P>Chris</BLOCKQUOTE>
Can't you rotate the points so that the normal to the plane they
lie in (which is
<BR> the normal to the cutting plane) is parallel to the z axis and
then use vtkDelaunay2D
<BR> to triangulate the points using just the x,y coordinates of
the points? Then you could rotate
<BR> the triangles/points back to the original orientation.
<P> Dave
<PRE>--
David E Jones
Du Pont Central Research
Experimental Station, Bldg 320
Wilmington, DE 19880-0320</PRE>
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