[vtkusers] Stencil operations like in OpenGL

[W.Leeson at pilz.ie]

Hi All,
        I am trying to do CSG operations in VTK with 2 areas enclosed with 
polygons. From my experience with OpenGL since we don't actually want the 
geometry is to use the stencil buffer to do this. Is there a way to do 
this kind of stencil operation in VTK?
        If not can VTK perform the clipping. I know it is possible with 
planar surfaces i.e. I can clip a group of polygons by an implicit 
function. However from what I understand I'd have to convert my polygon 
set to an implicit function (possible since it is an enclosed set) and 
then use that against the other polygon set. But this would be very slow 
as I would have to use crossing test or something like it to evaluate the 
implicit function and we need real time performance. Unfortunately the 
enclosed areas are not guaranteed to be convex so I can't use just plane 
clipping.
        Sorry about this query but I am new to VTK and trying to get to 
grips with it.

Regards,
William Leeson
Software Development

PILZ Ireland Industrial Automation,
Business & Technology Park, Model Farm Road, Cork, Ireland.
Telephone +353 (021)  4804-982, Fax +353 (021) 4804-994
E-Mail: mailto:w.leeson at pilz.ie, Internet: http://www.pilz.ie

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