[vtkusers] SetScalar() removes my color scalars

[Cory Quammen]

Doug,

This is a long-standing oddness in VTK. If you call SetScalars() on point
data, for example, a side effect is that the current active scalars is
removed from the point data! I have been bitten by this in the past. We
should probably change this behavior to avoid surprising effects like this
despite the backwards compatibility issues (which are hopefully few).

I recommend calling SetActiveScalars(const char* name) instead, which
shouldn't remove your array.

HTH,
Cory


On Thu, Mar 3, 2016 at 8:09 AM, jhirsch <jan.hirsch at st.ovgu.de> wrote:

> Hello Doug,
> your source example just creates two arrays and set their names and
> therefore has little to do with your problem, I guess. Can you copy more
> lines of code that show the problem with the scalar replacement?
>
> In general I would recommend to create a scalar array with 3 components and
> use that for colours. Like this:
>
> (that's from the example  here
> <http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/ColoredPoints>  )
>
>
>
>
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-- 
Cory Quammen
R&D Engineer
Kitware, Inc.
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