[vtkusers] Interactively updating the edge colors of a graph

[Steffen Oeltze]

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
Web:    http://www.vismd.de/