[PyOpenGL-Devel] [ pyopengl-Bugs-1850600 ] glMultMatrix does not work correctly with transposed arrays

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Bugs item #1850600, was opened at 2007-12-14 03:46
Message generated for change (Comment added) made by mcfletch
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Category: GL
Group: v3.0.0
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Toon Verstraelen (tovrstra)
Assigned to: Nobody/Anonymous (nobody)
Summary: glMultMatrix does not work correctly with transposed arrays

Initial Comment:
Hello,

In the example attached, it shown that the function glMultMatrixf does not work correctly with transposed arrays. Apparently, the strides of a numpy.array object are ignored. This problem is present in version 3.0.0a6. It was not present in the 2.x versions.

In the program bug.py, the relevant part is marked by comments 'BEGIN INTERESTING PART' and 'END INTERESTING PART'. When transf.transpose() is given as argument, glGetFloatv(GL_MODELVIEW_MATRIX) clearly shows the problem. When transf.transpose().copy() is given as argument, the problem is 'fixed', but not in a very satisfying way.

cheers,

Toon

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>Comment By: Mike C. Fletcher (mcfletch)
Date: 2008-01-07 10:35

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I'll take a look at the test case. PyOpenGL 2.x was doing a copy *all* the
time, so it was always using the unsatisfying solution.  PyOpenGL 3.x
*tries* not to do a copy, but it *should* do a copy (in the same manor)
under the covers... it doesn't try to figure out your array strides or the
like.  In this case it's apparently failing to do the copy when it should.

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