[vtkusers] How to evaluate angles in 3D

[Ocean Spring]

Dear All,

i have a problem on obtaining angles on a 3D surface. what i want to do is
to randomly pick up 3 points on an isosurface and evaluate
the degree of the angle formed by these three points.

i checked the AngleWidget.tcl but it is a 2D examples.

i tried to use

vtkAngleRepresentation3D
vtkAngleWidget

 the three points do not seem to "stick" on the surface but somewhere else.

can someone enlighten me on how to create an arbitrary angle on an
isosurface.



thank you

regards

O.S
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