[vtkusers] Bug in vtkOpenGLFreeTypeTextMapper::RenderOverlay(): prop picking leads to incorrect hidden surface removal

[Patric Weis]

Dear all,

there seems to be a bug in vtkOpenGLFreeTypeTextMapper::RenderOverlay().

Problem description
-------------------
After picking in a scene with 3D and 2D actors the depth buffering
for hidden surface removal does not work anymore.

The problem occurs under following circumstances:
- The render scene contains a mix of vtkProp3D and vtkActor2D objects.
- Picking with vtkPropPicker.

The attached file (DepthFuncBugDemo.zip) contains a tcl script that
demonstrates the problem. Start the script, rotate the cube and pick
somewhere in the render area by pressing the key 'p'. Now you can see
that the hidden parts of the cube have not been removed.

Solution
--------
In file vtkOpenGLFreeTypeTextMapper.cxx (Revision: 1.35,
2003/11/10 21:05:22) insert the following statement after
line 351:

     glDepthFunc(GL_LEQUAL);


Hope I'm right! ;)

Patric Weis
MYCRONA

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