[vtkusers] vtkActor : SetOrientation(x,y,z)

[Aurélie Larcher]

Hello,
About the vtkProp3D's function SetOrientation(double x, double y, double 
z) the documentation precises this :
"Sets the orientation of the Prop3D. Orientation is specified as X,Y and 
Z rotations in that order, but they are performed as RotateZ, RotateX, 
and finally RotateY."
OK but is anybody knows what are these angles ?
For exemple : (30,40,-50)
First.         Angle -50 ° from Z to Y
Second.    Angle 30° from X to Y
Third.       Angle 40° from Y to ?

It's really important for me to understand this, I hope someone could 
help me !
Aurélie