[vtkusers] vtkArrowSource and vtkGlyph3D

[Ken Martin]

Be aware Glyph3D is a filter and will actually generate all those arrows in
memory. Glyph3DMapper is a mapper and uses OpenGL tricks to render the same
arrow lots of times.

Both classes place a glyph at the location of each input point. The
orientation is controlled by a different array in your point data ala the
comments below:

Thanks
Ken

  //@{
  /**
   * Turn on/off orienting of input geometry.
   * When turned on, the orientation array specified
   * using SetOrientationArray() will be used.
   */
  vtkSetMacro(Orient, bool);
  vtkGetMacro(Orient, bool);
  vtkBooleanMacro(Orient, bool);
  //@}

  //@{
  /**
   * Orientation mode indicates if the OrientationArray provides the
direction
   * vector for the orientation or the rotations around each axes. Default
is
   * DIRECTION
   */
  vtkSetClampMacro(OrientationMode, int, DIRECTION, ROTATION);
  vtkGetMacro(OrientationMode, int);
  void SetOrientationModeToDirection()
    { this->SetOrientationMode(vtkGlyph3DMapper::DIRECTION); }
  void SetOrientationModeToRotation()
    { this->SetOrientationMode(vtkGlyph3DMapper::ROTATION); }
  const char* GetOrientationModeAsString();
  //@}

  enum OrientationModes
  {
    DIRECTION=0,
    ROTATION=1
  };


  /**
   * Tells the mapper to use an orientation array if Orient is true.
   * An orientation array is a vtkDataArray with 3 components. The first
   * component is the angle of rotation along the X axis. The second
   * component is the angle of rotation along the Y axis. The third
   * component is the angle of rotation along the Z axis. Orientation is
   * specified in X,Y,Z order but the rotations are performed in Z,X an Y.
   * This definition is compliant with SetOrientation method on vtkProp3D.
   * By using vector or normal there is a degree of freedom or rotation
   * left (underconstrained). With the orientation array, there is no
degree of
   * freedom left.
   * This is convenience method. The same effect can be achieved by using
   * SetInputArrayToProcess(vtkGlyph3DMapper::ORIENTATION, 0, 0,
   * vtkDataObject::FIELD_ASSOCIATION_POINTS, orientationarrayname);
   */
  void SetOrientationArray(const char* orientationarrayname);


On Fri, Dec 2, 2016 at 10:18 AM, Andrea Gavana <andrea.gavana at gmail.com>
wrote:

> Dear All,
>
>     I am trying to combine a vtkArrowSource and vtkGlyph3D. I have been
> (naively) thinking that by specifying a polydata with two points (start and
> end) and assigning its points to the vtkGlyph3D I would obtain an arrow
> that starts at the start point and end at the end point.
>
> I have created a small, self-contained following Python script to
> demonstrate what I mean - I get 4 arrows, one at each point I define,
> instead of two arrows. What am I missing? Any suggestion is more than
> welcome.
>
> Thank you in advance.
>
> Andrea.
>
>
> import vtk
> import numpy
>
> # First set of points - first arrow
> points1 = numpy.array([[ 11271.915, 7538.686, 6245.661],
>                        [ 11271.915, 7538.686, 5897.034]])
>
> # Second set of points - second arrow
> points2 = numpy.array([[ 10532.274, 9101.572, 6313.167],
>                        [ 10532.274, 9101.572, 5964.539]])
>
> # Create an arrow source with some attributes
> arrow_source = vtk.vtkArrowSource()
> arrow_source.SetTipRadius(0.2)
> arrow_source.SetShaftRadius(0.075)
>
> # Create the vtkGlyph3D
> arrow_glyph = vtk.vtkGlyph3D()
> arrow_glyph.SetScaleModeToDataScalingOff()
>
> # Usual mapper
> arrow_mapper = vtk.vtkPolyDataMapper()
> arrow_mapper.SetInputConnection(arrow_glyph.GetOutputPort())
>
> # Usual actor
> arrow_actor = vtk.vtkActor()
> arrow_actor.SetMapper(arrow_mapper)
>
> append_poly_data = vtk.vtkAppendPolyData()
>
> # Loop through points1 and points2
> for p in [points1, points2]:
>
>     arrow_poly_data = vtk.vtkPolyData()
>     vtk_arrow_lines = vtk.vtkCellArray()
>
>     vtk_arrow_lines.InsertNextCell(2)
>     vtk_arrow_lines.InsertCellPoint(0)
>     vtk_arrow_lines.InsertCellPoint(1)
>
>     vtk_arrow_points = vtk.vtkPoints()
>     # Loop through the head and tail of a single arrow
>     for j in xrange(2):
>         vtk_arrow_points.InsertNextPoint(p[j])
>
>     arrow_poly_data.SetPoints(vtk_arrow_points)
>     arrow_poly_data.SetLines(vtk_arrow_lines)
>     append_poly_data.AddInputData(arrow_poly_data)
>
>
> arrow_glyph.SetInputConnection(append_poly_data.GetOutputPort())
> arrow_glyph.SetSourceConnection(arrow_source.GetOutputPort())
> arrow_glyph.SetScaleFactor(100)
> arrow_actor.GetProperty().SetColor(1, 1, 1)
>
> # ------------------------------------------------------------
> # Create the RenderWindow, Renderer and both Actors
> # ------------------------------------------------------------
> ren = vtk.vtkRenderer()
> renWin = vtk.vtkRenderWindow()
> renWin.AddRenderer(ren)
> iren = vtk.vtkRenderWindowInteractor()
> iren.SetRenderWindow(renWin)
>
> # add actors
> ren.AddActor(arrow_actor)
> ren.ResetCamera()
> iren.Start()
>
>
>
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-- 
Ken Martin PhD
Chairman & CFO
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065
518 371 3971

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