[vtkusers] individually colored points in Python?

[Lucas]

Yes that and SetScalars make it work.

I changed the example code on
http://www.vtk.org/Wiki/VTK/Examples/Python/SolidColoredTriangle to use
SetScalars (not sure what the 'import hybrid' is there for, I didn't get it
with my python-vtk install so had to delete it to run the example)-

Thanks!

Lucas

On Wed, Feb 2, 2011 at 4:18 PM, David Gobbi <david.gobbi at gmail.com> wrote:

> Hi Lucas,
>
> Changing to SetScalars() was correct.  The SetVectors() method is not for
> colors.
>
> The bug in your code appears to be how you are filling in the array.  You
> need to instantiate the vtkUnsignedCharArray before the loop, not inside of
> the loop:
>
> #setup colors
> Colors = vtk.vtkUnsignedCharArray()
> Colors.SetNumberOfComponents(3)
> Colors.SetName("Colors")
>
> for i in range(255):
>   for j in range(255):
>     id = Points.InsertNextPoint(i, j, 1)
>     Vertices.InsertNextCell(1)
>     Vertices.InsertCellPoint(id)
>     Colors.InsertNextTuple3(255,i,j)
>
> They way you had written the code, you were creating 255 different arrays
> and setting only the first tuple of each one.
>
>   - David
>
>
> On Wed, Feb 2, 2011 at 2:27 PM, Lucas <wsacul at gmail.com> wrote:
>
>> I'd like to render a point cloud with points individually colored, so I
>> combined the example
>> http://www.vtk.org/Wiki/VTK/Examples/Python/TriangleColoredPoints with
>> others that sets up the interactive render window.  But the points are all
>> white, unless I call SetColor which gives them all the same color.  What am
>> I missing?
>>
>> import vtk
>>
>> # create a rendering window and renderer
>> ren = vtk.vtkRenderer()
>> renWin = vtk.vtkRenderWindow()
>> renWin.AddRenderer(ren)
>> renWin.SetSize(400,400)
>>
>> # create a renderwindowinteractor
>> iren = vtk.vtkRenderWindowInteractor()
>> iren.SetRenderWindow(renWin)
>>
>> #setup points and vertices
>> Points = vtk.vtkPoints()
>> Vertices = vtk.vtkCellArray()
>>
>> for i in range(255):
>>   for j in range(255):
>>     id = Points.InsertNextPoint(i, j, 1)
>>     Vertices.InsertNextCell(1)
>>     Vertices.InsertCellPoint(id)
>>
>>     #setup colors
>>     Colors = vtk.vtkUnsignedCharArray()
>>     Colors.SetNumberOfComponents(3)
>>     Colors.SetName("Colors")
>>     Colors.InsertNextTuple3(255,i,j)
>>
>> polydata = vtk.vtkPolyData()
>> polydata.SetPoints(Points)
>> polydata.SetVerts(Vertices)
>> polydata.GetPointData().SetVectors(Colors)
>> polydata.Modified()
>> polydata.Update()
>>
>> ######
>> mapper = vtk.vtkPolyDataMapper()
>> mapper.SetInput(polydata)
>>
>> actor = vtk.vtkActor()
>> actor.SetMapper(mapper)
>> ren.AddActor(actor)
>>
>> # enable user interface interactor
>> renWin.Render()
>> iren.Initialize()
>> iren.Start()
>>
>>
>> Replacing SetVectors() with SetScalars produces some point coloring, but
>> the colors seem random.
>>
>> I'm using vtk 5.4.2 and Python 2.6.6 on Ubuntu.
>>
>> Thanks,
>>
>> Lucas
>>
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