[vtkusers] A bug in vtkXOpenGLTextMapper

[Brad Arthur]

Hello,

I think I have tracked down a bug within vtkXOpenGLTextMapper.  I am running
Linux and VTK 3.1.2 (the official release, not the nightly update).

I have been receiving Segmentation faults since I added text annotations to
my vtkImageViewer.  (The Win98 version of my code works correctly)

To make sure that it was not just a problem with my code, I ran the TCL
script vtk31/graphics/examplesTcl/annotatePick.tcl.  It also gave me a
Segmentation fault.  After I commented out the line "ren1 AddActor2D
textActor", the mace appeared and I could interact with it.


I debugged through the code and found the problem in
vtkXOpenGLTextMapper.cxx.

When I came to this line (in the function RenderOpaqueGeometry()),

    glListBase(vtkXOpenGLTextMapper::GetListBaseForFont(this,viewport,
                                                        this->CurrentFont));

the value of this->CurrentFont was equal to 52428976.  However,
GetListBaseForFont() reveived the value as 135641512!!

The Seg fault occurs on this line (within GetListBaseForFont()),

    glXUseXFont(CurrentFont, 0, 255, cache[numCached]->ListBase);

which makes sense, since CurrentFont is the wrong value!


Has anyone out there had this problem??

Thanks,
Brad Arthur