[vtkusers] Possible Bug in vtkOrientationMarkerWidget / vtkProp

[Martin Meiler]

Hello everybody,

I am facing a problem when using a vtkOrientationMarkerWidget in a
python/pyQt
environment.

python 2.7.3
vtk 6.1
pyQt: 4.10.1

I first define the axesActor and axesMarker and later in the code ...

> self.axesActor = vtk.vtkAxesActor()
> self.axesMarker = vtk.vtkOrientationMarkerWidget()
> self.axesMarker.SetDefaultRenderer(self.renderer)
>
> self.axesMarker.SetInteractor(self.interact)
>
> self.axesMarker.SetOrientationMarker(self.axesActor)
>
> self.axesMarker.SetOutlineColor(0.9300, 0.5700, 0.1300)
>
> self.axesMarker.SetViewport(0.8, 0.0, 1.0, 0.2)
>
> self.axesMarker.SetEnabled(0)
>
> self.renderer.AddActor(self.axesActor)
>
> self.axesActor.VisibilityOn()
>
...
change the size of the orientation markers.
> self.axesActor.SetTotalLength(delta, delta, delta)

If the parameter delta is larger equal 5e-3, than everything looks fine.
However if I
use values smaller than 5e-3 the tips of the axesActor suddenly all
point in x-Direction and
the labels are not readable.

Can someone reproduce this behavior? Is this a bug?

Please find attached a python file that allows to reproduce this
behavior (at least on my machine).

Best regards
Martin

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# -*- coding: utf-8 -*-
"""
Created on Fri Jul 08 15:50:36 2016

@author: martin
"""
import sys
import vtk
from PyQt4 import QtGui
from vtk.qt4.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor

class MainWindow(QtGui.QMainWindow):
  def __init__(self, parent = None, radius=0.5):
    super(MainWindow, self).__init__(parent)
    
    self._sphereRad = radius
    
    self._initUI()
    self._initVtk()    

  def _initUI(self):
    """
    This method sets up the pyqt items
    """
    frame = QtGui.QFrame()
    self.vtkWidget = QVTKRenderWindowInteractor(frame)
   
    main_lhbox = QtGui.QHBoxLayout()
    main_lhbox.addWidget(self.vtkWidget)
    
    frame.setLayout(main_lhbox)
    self.setCentralWidget(frame)
    self.show()
    
  def _initVtk(self):
    """
    This method sets up the vtk objects
    """
    self.attrib = vtk.vtkCompositeDataDisplayAttributes()    
    self.mapper = vtk.vtkCompositePolyDataMapper2()
    self.mapper.SetCompositeDataDisplayAttributes(self.attrib)
    
    # Create an actor
    self.actor = vtk.vtkActor()
    self.actor.SetMapper(self.mapper)
    self.actor.GetProperty().SetInterpolationToFlat()
    self.actor.GetProperty().EdgeVisibilityOff()
    self.actor.GetProperty().SetOpacity(0.5)
    
    self.renderer = vtk.vtkRenderer()
    self.renderer.GradientBackgroundOn(); 
    self.renderer.SetBackground(1,1,1);
    self.renderer.SetBackground2(37./255, 127./255, 194./255);    
    self.renderer.AddActor(self.actor)
    
    self.vtkWidget.GetRenderWindow().AddRenderer(self.renderer)
    self.interact = self.vtkWidget.GetRenderWindow().GetInteractor()
    
    self.interact.Initialize()
    
    self.sphere = vtk.vtkSphereSource()
    self.sphere.SetRadius(self._sphereRad)
    self.sphere.Modified()
      
    self.geoF = vtk.vtkDataSetSurfaceFilter()
    
    self.axesActor = vtk.vtkAxesActor()    
    self.axesMarker = vtk.vtkOrientationMarkerWidget()
    self.axesMarker.SetDefaultRenderer(self.renderer)
    self.axesMarker.SetInteractor(self.interact)
    self.axesMarker.SetOrientationMarker(self.axesActor)
    self.axesMarker.SetOutlineColor(0.9300, 0.5700, 0.1300)
    self.axesMarker.SetEnabled(0)
    self.renderer.AddActor(self.axesActor)
    self.axesActor.VisibilityOn()
    
    self.axesActor.SetTotalLength(0.5*self._sphereRad,
                                  0.5*self._sphereRad,
                                  0.5*self._sphereRad)
    
    self.geoF.SetInputConnection(self.sphere.GetOutputPort())
    self.mapper.SetInputConnection(self.geoF.GetOutputPort())
    
    style = vtk.vtkInteractorStyleTrackballCamera()
    self.renderer.GetActiveCamera().ParallelProjectionOff()
    self.interact.SetInteractorStyle(style)
    style.EnabledOn()
    
    self.renderer.ResetCamera(self.mapper.GetBounds())
    
    

if __name__ == "__main__":
 
    app = QtGui.QApplication(sys.argv)
    window = MainWindow(radius=9e-3)
  
    sys.exit(app.exec_())