[vtkusers] How to put vtkImagePlaneWidget behind actors ?

[Charl P. Botha]

Hi Istvan and Dean,

On 8/8/06, Dean Inglis <dean.inglis at camris.ca> wrote:
> I'm not sure how to address the issue you raise,
> since I never use vtkImagePlaneWidget in this way
> (overlay transparent actors/widgets etc.)  Can you
> provide a short tcl script that uses a vtk test data
> set (like headsq) that illustrates the problem?  I
> could take a look in more detail then...

This is an old issue, to do with the even older issue of rendering
multiple intersecting transparent objects correctly.

The problem is that the vtkImagePlaneWidget, in its default
configuration, is considered to be possible transparent (and it can
easily be made transparent).  To fix this in cases where you are not
going to use a colourmap that'll result in a transparent IPW, do the
following:

IPW->GetColorMap()->SetOutputFormatToRGB();
IPW->GetColorMap()->PassAlphaToOutputOff();

Dean, you added the GetColorMap() method a long time ago at my
request, for just this purpose.  The documentation does mention how to
do this already...  search for "transparent" in
http://www.vtk.org/doc/nightly/html/classvtkImagePlaneWidget.html

See you,
Charl