[vtkusers] Problem with vtkTkRenderWidget and CrystalEyes stereo

[Michael Scarpa]

On Mon, Jul 10, 2006 at 05:33:25PM +0100, Jens Thomas wrote:
> Michael Scarpa wrote:
> >Jens Thomas wrote:
> >>I'm trying to get vtk to use CrystalEyes stereo with a
> >>vtkTkRenderWidget, but am hitting a problem in that the render window I
> >>create is not stereo capapble, and I therefore get the error message:
> >>
> >>vtkXOpenGLRenderWindow (0x8351740): Adjusting stereo mode on a window
> >>that does not support stereo type CrystalEyes is not possible.
> >>
> >>I call vtkTkRenderWidget with the "stereo=1" flag to generate a widget
> >>with a renderwindow that is stereo capable, and then call the
> >>GetRenderWindow method on the widget to get the RenderWindow. However,
> >>the RenderWindow I get back is not stereo capable, as illustrated by the
> >>error message above. This is despite the fact that the window that is
> >>initially created within vtkTkRenderWidget is stereo capable.
> >>
> >>I checked this with a print statement in the file:
> >>
> >>VTK/Wrapping/Python/vtk/tk/vtkTkRenderWidget.py
> >>
> >>at line 89, where it checks the keyword dictionary as shown below:
> >>
> >>try:  # was a stereo rendering context requested?
> >>            if kw['stereo']:
> >>               print "Setting stereo"
> >>               renderWindow.StereoCapableWindowOn()
> >>               print renderWindow
> >>               del kw['stereo']
> >>        except KeyError:
> >>            pass
> >>
> >>At the point of the print statement, the window is stereo capapble.
> >>
> >>It therefore seems that the window returned by the GetRenderWindow is
> >>not the same one as was first created.
> >>
> >>If I create the render window directly, and avoid the vtkTkRenderWidget
> >>side of things, it appears to work o.k.
> >>
> >>I've pasted in an example below that demonstrates the problem - setting
> >>the tk variable to 0 or 1 turns off the Tk code and shows that it
> >>appears to work if you don't use the  vtkTkRenderWidget code.
> >>
> >>Any suggestions/help would be greatly appreciated.
> >>
> >>from Tkinter import *
> >>from vtk import *
> >>from vtk.tk.vtkTkRenderWidget import *
> >>
> >># Set the tk variable to 0 to eschew the Tk code
> >>tk=1
> >>if tk:
> >>    # Make a root window
> >>    root = Tk()
> >>    # Add a vtkTkRenderWidget
> >>    renderWidget = vtkTkRenderWidget(root,stereo=1)
> >>    renderWidget.pack()
> >>    # Get the render window from the widget
> >>    renWin = renderWidget.GetRenderWindow()
> >>    print "renWin is"
> >>    print renWin
> >>else:
> >>    renWin = vtk.vtkRenderWindow()
> >>    renWin.StereoCapableWindowOn()
> >>    print "renWin is"
> >>    print renWin
> >>    iren = vtk.vtkRenderWindowInteractor()
> >>    iren.SetRenderWindow(renWin)
> >>
> >>renWin.SetStereoTypeToCrystalEyes()
> >>#renWin.SetStereoTypeToRedBlue()
> >>renWin.StereoRenderOn()
> >>
> >># Next, do the VTK stuff
> >>ren = vtkRenderer()
> >>renWin.AddRenderer(ren)
> >>cone = vtkConeSource()
> >>cone.SetResolution(16)
> >>coneMapper = vtkPolyDataMapper()
> >>coneMapper.SetInput(cone.GetOutput())
> >>coneActor = vtkActor()
> >>coneActor.SetMapper(coneMapper)
> >>ren.AddActor(coneActor)
> >>
> >>
> >># start up the event loop
> >>if tk:
> >>    root.mainloop()
> >>else:
> >>    iren.Initialize()
> >>    renWin.Render()
> >>    iren.Start()
> >>    
> >
> >Have you tried the same things with vtkTkRenderWindowInteractor instead
> >of vtkTkRenderWidget? With the former, you can create your own
> >vtkRenderWindow instance and provide it to the widget for use.  It
> >would be interesting to see if you encounter the same problem in this
> >case, since you can create your own render window and set its
> >capabilities yourself before handing it over to Tk.
> >
> I've been playing around with this a bit more and have got a little 
> further, although I'm still stuck.
> 
> You can actually create your own window with the vtkTkRenderWidget and 
> pass it in too, so I tried this and still had the same problem. I've 
> therefore tried to remove Python from the equation by writing a Tcl 
> script that does exactly the same thing (well, I think it does - I've 
> never used Tcl before) . It seems that the vtkTkRenderWidget doesn't 
> accept a -stereo argument, so I have to create the render window myself 
> and then pass it in.
>
> However, even doing this, the code demonstrates exactly the same 
> problems as calling the routine from Python, so it seems that the 
> problem resides in the Tcl/Tk side of things. I've pasted the code into 
> the tail of this email in case anyone wants to try it.
> 
> I've tried this with the VTK 5.0 on Windows, Mac OSX and Linux, and 
> things seem to work fine on Windows and Mac OSX, but not under Linux - 
> and unfortunately, it's Linux that I need this to work on.

Just a crazy thought, but ... are you sure the graphics card of the
Linux machine you are using is able to produce active stereo images?
Because if not, vtk won't produce any error messages (at least in my
experience) and simply not render in active stereo.

> I've tried this on Linux running Suse 9.3 on a Pentium with tcl 8.4.9-7 
> and tk 8.4.9-9, as well as a RHEL 3 on a Intel Xeon with tcl 8.3.5-92.4 
> and tk 8.3.5-92.4, so it doesn't appear to be specific to a brand of 
> Linux/version of Tk/Tcl.
> 
> If anyone can suggest where I go from here, I'd be most grateful to hear 
> from you!
> 
> package require vtk
> package require vtkinteraction
> 
> # Create the render window to pass to the vtkTkRenderWidget
> vtkRenderWindow renWin1
> renWin1 StereoCapableWindowOn
> # At this point the window is stereo capable
> puts stdout [renWin1 Print]
> 
> set renderWidget [vtkTkRenderWidget .ren -width 400 -height 400 -r renWin1]
> ::vtk::bind_tk_render_widget $renderWidget
> wm protocol . WM_DELETE_WINDOW ::vtk::cb_exit
> pack $renderWidget
> 
> # Return the render window from the vtkTkRenderWidget
> set renWin [$renderWidget GetRenderWindow]
> 
> # This should be the same window as was created before, but it is not 
> stereo capapble
> puts stdout [$renWin Print]
> 
> $renWin SetStereoTypeToCrystalEyes
> $renWin StereoRenderOn
> 
> vtkRenderer ren
> $renWin AddRenderer ren
> vtkConeSource cone
> cone SetResolution 16
> vtkPolyDataMapper coneMapper
> coneMapper SetInput [cone GetOutput]
> vtkActor coneActor
> coneActor SetMapper coneMapper
> ren AddActor coneActor
> 
> $renderWidget Render
> tkwait window .

I have tried your code on a Linux machine here.  The script works fine
and I get an active stereo image.

Furthermore, you say in your Tcl/Tk code that $renWin should be the same
window as $renWin1, but that it is not.  How did you conclude that?  In
the output the script generated for me, the address of the two objects
was the same, but some parameters did indeed change.  Nevertheless, it
would seem to me that the two variables point to the same object in
memory, even though it gets modified by the initialization.

I hope this helps.

Kind regards,

Michael