[pypy-dev] (no subject)

[renaud blanch]

hi,

i'm trying to make some pyopengl [0] -based code [1] run on top of pypy.
this is partially successful, but i need some advice to progress further.
pyopengl 3.x makes use of ctypes to provide the opengl binding, and it
works out of the box for simple functions (those that do not takes
c-pointer to buffers of data as arguments).
for the rest, the first issue is that pyopengl use two functions from
the ctypes.pythonapi lib, namely PyString_AsString and
PyBuffer_FromMemory.
any advice on how to replace those functions to make them compatible with pypy?

Mike Fletcher (pyopengl author) gave me some hints about that point:
> For the first issue, those are going to require some reworking, in
> essence those are "C" implemented code that happens to use Python/ctypes
> as the implementation language and makes assumptions about the
> data-storage for the objects (e.g. that a string is internally a
> contiguous series of bytes, which is *not necessarily* true in PyPy).
> We'd need to find a mechanism in PyPy that would give us that direct
> memory-pointer access to be able to use it.  Note: a compacting garbage
> collector (or anything else that can move memory locations) will cause
> problems there, so we may need to find a way to signal PyPy not to move
> a given object, and to use contiguous data-arrays for their storage.

thanks a lot for any advice,

renaud

0. PyOpenGL 3.x / The Python OpenGL® Binding
<http://pyopengl.sourceforge.net/>

1. opengl-programmable / a short step by step tutorial to OpenGL
programmable pipeline
<http://bitbucket.org/rndblnch/opengl-programmable/>