[vtkusers] Black lines?

Jeff Lee jeff at cdnorthamerica.com
Fri Oct 18 11:34:23 EDT 2002

John Norris wrote:

>I'm using VTK4.0, so if some of these things have been addressed in 4.1,
>please forgive me.
>I'm using vtkTensorGlyph with a vtkAxes as the source (with symmetry turned
>on), and I've run into a few problems.
>First, the output of vtkTensorGlyph eventually is run through
>vtkPolyDataNormals (the glyph is often a sphere or cone, and the output may
>be clipped, capped and triangulated, and I have to use vtkPolyDataNormals to
>avoid some strange lighting effects at sharp corners).  When I'm using vtkAxes
>as the glyph, however, vtkPolyDataNormals panics because there are neither
>polys nor strips in its input.  It would be much more convenient if it would
>just pass the data through in this case (perhaps with a warning), rather than
>give up completely.  I can fix this myself without changing the library by
>deriving a new class from vtkPolyDataNormals, so that's not such a big deal.
>Second, vtkTensorGlyph::SetScaling() and family has no effect.
>Finally, when using vtkAxes as a glyph, I've noticed that sometimes the lines
>are the correct color, and sometimes they're black.  It seems to depend on
>the camera's orientation.  I would like the lines to have the same color
>regardless of what direction I'm looking at them from.  Is there a way to
>do this?  This is the most pressing issue for me.
Could this be a matter of setting Ambient=1.0, Diffuse=0.0 on the actor 
representing the glyph?

>Thanks for any advice,

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