GitLab

Today I recognized a strange behaviour of the vtkAngleWidget. (version 9.0 commit 1762d09c) When initializing the widget programmatically with three points (all laying on the YZ-plane) the widget does not compute the angle.

The problematic section of code is in vtkAngleRepresentation3D line 293.

// Compute the angle (only if necessary since we don't want
// fluctuations in angle value as the camera moves, etc.)
if (p1[0] - c[0] == 0.0 || p2[0] - c[0] == 0.0)
{
    return;
}

Here, the BuildRepresentation() method returns if the x-coordinates of the points are the same (why is it that way?). Is that a bug, or an intended behaviour?

In my use case (CT Viewer) I cannot measure 3D angle if the picked world coordinates originate from the sagittal plane (x-coordinates of all three points are the same). For an example image of the imcomplete angle measurement of the vtkAngleWidget see attached image file.