[vtkusers] Using multiple Vectors

[Amy Henderson]

Hi Uwe,

You could do this with a branching pipeline. You'll need two instances of 
vtkAssignAttribute, vtkGlyph3D, vtkMapper, and vtkActor. The code would 
look something like the following.

attribute1 = vtkAssignAttribute()
attribute2 = vtkAssignAttribute()
glyph1 = vtkGlyph3D()
glyph2 = vtkGlyph3D()
mapper1 = vtkPolyDataMapper()
mapper2 = vtkPolyDataMapper()
actor1 = vtkActor()
actor2 = vtkActor()

# glyph using vector 1
attribute1.SetInput(unstructGrid)
attribute1.Assign('FIRST', 'VECTORS', 'POINT_DATA')
glyph1.SetInput(attribute1.GetOutput())
glyph1.SetSource(arrow.GetOutput())
mapper1.SetInput(glyph1.GetOutput())
actor1.SetMapper(mapper1)

# glyph using vector 2
attribute2.SetInput(unstructGrid)
attribute2.Assign('SECOND', 'VECTORS', 'POINT_DATA')
glyph2.SetInput(attribute2.GetOutput())
glyph2.SetSource(arrow.GetOutput())
mapper2.SetInput(glyph2.GetOutput())
actor2.SetMapper(mapper2)

- Amy

At 10:56 AM 2/25/2004, Uwe Rempler wrote:
>hi list,
>
>i'm looking for a way to visualize more than one vectorarrow per point 
>(displacement-vector / another-vector) - for example somehow like this:
>
>#------------------------------------------------------------------------------- 
>
>firstVectorArray = vtkFloatArray()
>firstVectorArray.SetName('FIRST')
>secondVectorArray = vtkFloatArray()
>secondVectorArray.SetName('SECOND')
>unstructGrid = vtkUnstructuredGrid()
>attribute = vtkAssignAttribute()
>arrow = vtkArrowSource()
>glyph = vtkGlyph3D()
>mapper = vtkPolyDataMapper()
>actor = vtkActor()
># just imagine the grid and the vetorarrays are filled with lots of data ;-)
>
>unstructGrid.GetPointData().AddArray(firstVectorArray)
>unstructGrid.GetPointData().AddArray(secondVectorArray)
>
>attribute.SetInput(unstructGrid.GetOutput())
>attribute.Assign('FIRST', 'VECTORS',  'POINT_DATA')      << here's the 
>problem: either 'FIRST' or 'SECOND'
>attribute.Assign('SECOND', 'VECTORS',  'POINT_DATA')      << array but not 
>both at the same time...
>attribute.Update()
>
>glyph.SetInput(attribute.GetOutput())
>glyph.SetSource(arrow.GetOutput())
>
>mapper.SetInput(glyph.GetOutput())
>actor.SetMapper(mapper)
>etc...
>#------------------------------------------------------------------------------- 
>
>
>i know that this isn't working cause there was already a question about 
>how to handle more than one vector simultaneous:
>http://public.kitware.com/pipermail/vtkusers/2002-June/011932.html
>and the answer said that "there can be only one active "attribute" of each 
>type (scalar, vector, normal etc.) at one time" when using AddArray()...
>does anybody know a way of showing two vectors at the same time? or should 
>i just add another actor showing the second vector array arrows...?
>
>greetings
>uwe
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