[PyOpenGL-Devel] [ pyopengl-Bugs-1744414 ] ctypes.ArgumentError in glReadPixels

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Bugs item #1744414, was opened at 2007-06-27 15:04
Message generated for change (Comment added) made by mcfletch
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Category: GL
Group: v3.0.0
>Status: Closed
>Resolution: Out of Date
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
>Assigned to: Mike C. Fletcher (mcfletch)
Summary: ctypes.ArgumentError in glReadPixels

Initial Comment:

We're running problems with glReadPixels throwing an exception. Here's the backtrace:

Traceback (most recent call last):
  File "/store/home/mukaissi/MetNetVis/MetNetVis/UI/graphdrawwidget.py", line 155, in mousePressEvent
    index=GL.glReadPixels(event.x,event.y,1,1,GL.GL_RGB,GL.GL_UNSIGNED_BYTE)
  File "/store/home/mukaissi/software/PyOpenGL-3.0.0a6/OpenGL/GL/images.py", line 279, in glReadPixels
    ctypes.c_void_p( arrayType.dataPointer(array))
ctypes.ArgumentError: argument 1: <type 'exceptions.TypeError'>: wrong type

Adding a few prints to see the types of the involved variables they seem to be ok:

array: [[[0 0 0]]] <type 'numpy.ndarray'>
arrayType: <class 'OpenGL.arrays.arraydatatype.GLubyteArray'> <type '_ctypes.PointerType'>
dataPointer: 20509152 <type 'long'>

This is using 3.0.0a6 on an x86_64 (RHEL) system.

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>Comment By: Mike C. Fletcher (mcfletch)
Date: 2008-01-19 12:06

Message:
Logged In: YES 
user_id=34901
Originator: NO

With current CVS on AMD64 Gentoo the function appears to be working
correctly (as tested with the OpenGLContext/tests/saveimage.py script).

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