[vtkusers] understand projection of mouse coordinates in vtk3DWidget

[Leandros Fernandez]

I'd like to understand how exactly mouse motion is translated into movement in 3D space of the vtk3DWidgets.

For example: /Examples/GUI/Python/ProbeWithPointWidget.py
Apparently I can move the point widget along all three axes for any fixed scene orientation.
I think that the mouse x,y-coordinated must be projected onto some plane in 3D space, which touches the point widget. Correct? But WHICH plane?

Where can I find a more detailed explanation on widget interaction besides that widgets can be moved in 3D by the mouse? In "The Visualization Toolkit (3rd Edition)" they write "The initial direction of motion is used to determine which of the axes the user is moving the endpoint along". But this doesn't explain much.

Leandros



      
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