[vtkusers] Actor Lighting and Mapper ScalarVisibility

[Eduardo Kortright]

I am displaying an actor with its mapper set to ScalarVisibilityOn to color
the actor based on its scalar values.

After playing with the actor's diffuse lighting coefficient, I concluded
that lighting has no effect when color mapping is turned on.  The specular
coefficient does have an effect, however.

After playing with the ambient coefficient I found out that the diffuse
coefficient does have an effect, provided the ambient coefficient is
non-zero.  Similarly, the ambient lighting has no effect if the diffuse
coefficient is zero.

Since ambient and diffuse reflection are not linked when scalars are not
used, why are they dependent on one another with scalars are turned on?
Could this be a bug, or is this the intended functionality?

I am using VTK 4.0 on Win XP.

--------------------[ Eduardo Kortright
eduardo at cs.uno.edu ][ Department of Computer Science
Phone 504 280-6626 ][ University of New Orleans
FAX   504 280-7228 ][ New Orleans, LA 70148