[vox-tech] VTK 3D image capturing

[Jonathan Stickel]

What's a "double buffer"?  Really, until 2 days ago I've never even 
thought about how X is programmed.  Is there a good web reference?

Thanks Mark!
Jonathan


Mark K. Kim wrote:
> Can you double buffer the output and save the buffered image?
> 
> -Mark
> 
> 
> On Mon, 4 Oct 2004, Jonathan Stickel wrote:
> 
> 
>>Jeff Newmiller wrote:
>>
>>>I detest programs designed to behave this way... from "helpful" cpu status
>>>displays to "Did you really want to quit this program?" dialog boxes to
>>>"Your Windows resources are running low" to "We are backing up your
>>>data... please wait" dialog boxes... they all suffer from either hubris or
>>>programmers who couldn't handle multitasking. Please stop trying to take
>>>control away from the users ... there has to be a way to avoid this
>>>unfriendly behavior in your software ... be creative and find it.
>>>
>>
>><snip>
>>
>>I appreciate your comments.  Let me explain a little bit more about my
>>problem.  I am helping with a 3D visualization add-on (octaviz, built on
>>VTK) for a numerical math package (octave).  Octave typically runs as a
>>command-line interpreter in a shell window.  Graphing commands (and now
>>visualization commands) generate new windows that contain
>>graphs/graphics.  2D plots can be exported in some vectorized format, of
>>course.  The 3D visualizations, however, are complex, opengl rendered
>>objects with mouse interaction to rotate, zoom, etc.  Image "snapshots"
>>of the windows are often the only way to get a desired export of the
>>visualization.  There are functions in VTK to do just this, but the
>>rendered window MUST be on top to work; otherwise, it exports whatever
>>screen image is over the top of the VTK window.  And yes, I do consider
>>this to be a feature problem in VTK, but I do not have the technical
>>expertise nor time to make changes to VTK.
>>
>>So... a quick and easy fix for me is to force the window on top before
>>my export command saves the window as an image.  I did spend all weekend
>>looking through Xlib programming docs to see if I could get around this
>>some way, for example by keeping the window data in memory when it is
>>covered up.  Another option is off-screen rendering, but that path isn't
>>short either.
>>
>>If anyone has further suggestions, I would be happy to hear them.  For
>>now I /try/ to bring the window to the top and have a warning in the
>>user docs about this.
>>
>>Thanks,
>>Jonathan
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> 
>