[vtkusers] show ImageCursor3D Xor'ed over original image

[Florian Schmidt]

Hi.

I use the vtkImageCursor3D class to draw a cursor into the output of a
reslice object (which is used to extract slices from a mri-dataset).
Now, the 3d cursor just overpaints the original image. 

Is there a trivial way of making the cursor color value the xor'ed
picture value beneath it (so that this information doesn't get lost for
the examiner)?

I was thinking about using vtkImageLogic with the cursor as a source and
the reslice as another, but then i thought: "hmm, without the reslice
connected to the cursor's input, it won't know the right data extent and
will cry :). When i connect the input i will have the image in both
sources (the reslice output and the output of the cursor).". Both cases
are different from a (wishful thinking from a users point of view)
trivial approach as:

Cursor3D->SetLogicFunctionToXOR();

:)

So, maybe i use an alltogether wrong approach. Can someone shed some
light?

TIA

FLorian Schmidt

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