[vtkusers] VTK, Python, MacOS X, Cocoa, Offscreen rendering?

[Bridgman, William T.]

Hello,

I've found some posts from June 2004 ("Mac offscreen drawing")  
suggesting that VTK should be able to do offscreen rendering through  
the Cocoa interface, but that this was not yet implemented.  Has this  
changed?

I looked at vtkXOpenGLOffScreenRenderWindow but this seems to require  
that I get *everything* else running under X: Tcl/Tk and python, a  
process that has not gone well.

I'm trying to batch export RIB files on an XGrid cluster (Hundreds of  
files that take 5-15 minutes to process).

I've got vtkPython running with Cocoa but haven't found the sequence  
of commands that completely disables the window generation.  My  
simple-minded first guesses of

             renWin=vtk.vtkCocoaRenderWindow()
             renWin.OffScreenRenderingOn()

before installing actors, die with:

kCGErrorRangeCheck : Window Server communications from outside of  
session allowed for root and console user only
INIT_Processeses(), could not establish the default connection to the  
WindowServer.Abort

when run on the headless machines.  It runs fine without off-screen  
rendering on a console, though I believe some window briefly  
appears.  I suspect I'm missing something in the initialization  
sequence but am not that familiar with Cocoa.

Platform: MacOS X 10.4.11, G5 PPC.  VTK 5.1+ (from CVS)

Suggestions?

Thanks,
Tom

**** Please Update my e-mail address to my *NEW* OneNASA address  
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Dr. William T."Tom" Bridgman               Scientific Visualization  
Studio
Global Science & Technology, Inc.          NASA/Goddard Space Flight  
Center
Email: William.T.Bridgman at nasa.gov         Code 610.3
Phone: 301-286-1346                        Greenbelt, MD 20771
FAX:   301-286-1634                        http://svs.gsfc.nasa.gov/