[vtkusers] Re: VTK & Offscreen "MangledMesa" capabilities

[Brad King]

Randall Hand wrote:

> Ahh, just answered my question with "vtkMesaFreetypeTextMapper".
> 
> alot of the vtkMesa* objects state (in the documentation) that they
> shouldn't be used as their parent objects will automatically determine
> whether to use the Mesa or OpenGL version.  But it seems that I have
> to explicitly specify creation of the Mesa widgets to get this to
> work.  Am I doing something wrong, or is this by-design?

See these methods:

   // Description:
   // This option enables the creation of Mesa classes
   // instead of the OpenGL classes when using mangled Mesa.
   static void SetUseMesaClasses(int use);
   static int  GetUseMesaClasses();

on vtkGraphicsFactory and vtkImagingFactory.  Basically the parent 
classes don't know how to choose between Mangled Mesa and the normal 
OpenGL functions because they can both be present at the same time.  The 
comment about choosing between Mesa and OpenGL is for non-mangled mesa 
because only one of the two can be present in a single executable.

-Brad