[vtkusers] how to make some of my data invisible

[pratik]

Hi everyone,
I am writing a filter which takes one input and one source (it is a 
modified glyph filter). Some of my glyphs may be invalidated by the 
input, in which case i would like to keep them invisible. Is there a way 
to do this without modifiying the polydata instance in which i am 
storing the source? I have found that vtkPolyDataAppend to be a little 
bit slow, which is why i was hoping to simply make the rogue glyph 
invisible instead.

thanks,
pratik