[vtkusers] vtkDepthSortPolyData: Sorting polygons for transparency...

[Will Schroeder]

The class vtkDepthSortPolyData was checked in recently. It sorts
polygons/primitives along a vector: either a manually defined vector
or the vector defined by the focal point and position of the camera.
It can also take into account a transformation associated with a
vtkProp3D. See contrib/examplesTcl/depthSort.tcl.

It's not the final answer for fixing transparency since it only sorts
within a single dataset, and it sorts based on a single position within
the primitive (first point), i.e., polygon splitting is not performed and
polygons will occasionally be rendered in the wrong order.

Thanks to Scott Hill (a student at RPI) who originally implemented this class.

Will

--------------------------------
Dr. William J. Schroeder
Kitware Visualization Solutions / vtk Commercial Support
469 Clifton Corporate Parkway
Clifton Park, NY 12065
will.schroeder at kitware.com
1-518-371-3971 (Phone & Fax)