[vtkusers] vtkFollower as part of a vtkAssembly

Ron Inbar rinbar at netvision.net.il
Sat Sep 8 08:18:03 EDT 2001

Hi all,

In my application I want to place a labeled arrow in a dynamic scene.  The label is a vtkFollower with a vtkVectorText as its source.  The arrow has to be transformed according to some vtkTransform.  My problem is how to correctly place the label without losing vtkFollower functionality.  I tried two approaches; both failed:
1. Uniting the arrow with the label as a vtkAssembly.  This approach disabled the vtkFollower functionality (the label no longer turned to face the camera).
2. Transforming the label separately, using vtkProp::SetUserTransform with the same vtkTransform as for the arrow.  In this case the vtkTranform was concatenated with the transformation that was supposed to make the label face the camera, but they were concatenated in the wrong order, sending the label to some far-off location.
I thought of a third approach, but I don't know how to implement it.  Instead of using vector text, use raster text.  This eliminates the need for a vtkFollower altogether.  I know under OpenGL it's a piece of cake (using glRasterPos), but I don't know how to do it from VTK.

If you know the solution, please tell me ASAP, because I have a very pressing deadline (Sunday evening, GMT, to be precise).

Many thanks in advance,


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