[vtkusers] Ruler / Viewport

[Jean-Hugues Royer]

Hi,

What is the correct actor to display a ruler with a tick every 1 cm and 
which stays on the viewport ?

I tried vtkLegendScaleActor but the tick distance can not be modified to 
1 cm.

I also tried vtkAxisActor2D but if I use the viewport coordinate system 
(to draw it on the viewport) the ticks distances are in viewport 
coordinates and not in world coordinates.

Any idea ?

Thanks.