[vtkusers] Interactively updating the edge colors of a graph

[Steffen Oeltze]

Thanks Jeff for the quick and helpful reply. I will update my VTK 
installation as soon as possible.

Steffen

On 10.02.2011 20:53, Jeff Baumes wrote:
> Steffen,
>
> Thanks for your detailed report. The issue was that the filter that 
> updated colors (vtkApplyColors) did not update when the underlying 
> lookup table is modified. I just pushed a change to VTK master that 
> fixes this. The following python script shows how to change the lookup 
> table and re-render the view:
>
> from vtk import *
> import time
>
> s = vtkRandomGraphSource()
> view = vtkGraphLayoutView()
> rep = view.SetRepresentationFromInputConnection(s.GetOutputPort())
> rep.ColorVerticesByArrayOn()
> lut = vtkLookupTable()
> lut.Build()
> theme = vtkViewTheme()
> theme.SetPointLookupTable(lut)
> view.ApplyViewTheme(theme)
> view.ResetCamera()
> view.Render()
> time.sleep(2)
>
> # Modify the lookup table
> lut.SetHueRange(0.0, 0.0)
> lut.Build()
> view.Render()
> time.sleep(2)
>
> Jeff
>
> On Tue, Feb 8, 2011 at 11:18 AM, Steffen Oeltze 
> <stoeltze at isg.cs.uni-magdeburg.de 
> <mailto:stoeltze at isg.cs.uni-magdeburg.de>> wrote:
>
>     Dear VTK-users
>
>     I have written an application that displays a graph with colored
>     edges. The application is interactive and I would like to change
>     the edge coloring depending on some user interaction. The coloring
>     is accomplished via a vtkLookupTable and a vtkViewTheme. I tried
>     two different strategies so far. Unfortunately, only the second
>     one works which I guess is slower and less effective than the
>     first one. The first one only works if I manually enforce a new
>     rendering of the graph by selecting, e.g., an edge. In my source
>     code, I tried several update mechanisms, e.g., calling Modified()
>     on the vtkViewTheme after reassigning the modified vtkLookupTable,
>     but none of them worked. Any help on how I can imitate the
>     update-mechanism which is initiated after edge selection is deeply
>     appreciated.
>
>     1.) (works only after manual update)
>     - generate the vtkLookupTable, a vtkViewTheme, and a
>     vtkGraphLayoutView
>     - assign the vtkLookupTable to the vtkViewTheme
>     - assign the vtkViewTheme to the vtkGraphLayoutView
>     - render the graph
>     ...user interaction...
>     - update the vtkLookupTable
>     - render the graph again
>
>     2.) (works)
>     - generate the vtkLookupTable, a vtkViewTheme, and a
>     vtkGraphLayoutView
>     - assign the vtkLookupTable to the vtkViewTheme
>     - assign the vtkViewTheme to the vtkGraphLayoutView
>     - delete the vtkViewTheme
>     - render the graph
>     ...user interaction...
>     update the vtkLookupTable
>     - generate a new vtkViewTheme
>     - assign the modified vtkLookupTable to the new vtkViewTheme
>     - assign the new vtkViewTheme to the vtkGraphLayoutView
>     - delete the new vtkViewTheme
>     - render the graph again
>
>     Steffen
>
>     -- 
>     Dr.-Ing. Steffen Oeltze
>     Department of Simulation and Graphics, School of Computer Science
>     Otto-von-Guericke-University Magdeburg
>
>     Universitätsplatz 2, 39106 Magdeburg
>     GERMANY
>
>     Phone:  (+49-391) 67-1 25 27
>     Fax:    (+49 391) 67-1 11 64
>     Email: stoeltze at isg.cs.uni-magdeburg.de
>     <mailto:stoeltze at isg.cs.uni-magdeburg.de>
>     Web: http://www.vismd.de/
>
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>
>
>
> -- 
> Jeff Baumes, Ph.D.
> Technical Lead, Kitware Inc.
> (518) 881-4932


-- 
Dr.-Ing. Steffen Oeltze
Department of Simulation and Graphics, School of Computer Science
Otto-von-Guericke-University Magdeburg

Universitätsplatz 2, 39106 Magdeburg
GERMANY

Phone:  (+49-391) 67-1 25 27
Fax:    (+49 391) 67-1 11 64
Email:  stoeltze at isg.cs.uni-magdeburg.de
Web:    http://www.vismd.de/

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