[PyOpenGL-Users] Calling pyopengl developers.. PBO problems.
Brought to you by:
mcfletch
From: qzm <stu...@gm...> - 2005-09-27 23:02:58
|
Well, its been over 6 MONTHS since I pointed out this rather major problem in glreadpixels, and so far no reaction? Does anyone else find this a problem? without it we cannot use PBO (pixel buffer objects), which is a major addition to the opengl spec, and gives access to a whole range of important new functionality. It really would be nice to stop having to use custom C python extensions that need maintennce just to allow this one call.. >From: qzm <stuartaw@gm...> > glReadPixels spec problem. >2005-02-28 16:42 > Hello fellow pyOpengl Users. > > Perhaps I am missing something, but Ithink there is a serious issue > with glReadPixels. > > When using glReadPixels in combinations with pixel buffer objects > (PBOs) the last (C) argument is no longer the address of memory to > move the data to, but an offset from the currently defined buffer > object base. > > As a trivial example it is connon to use: > glReadPixels(0,0,640,480,GL_BGRA,GL_UNSIGNED_BYTE,0) > Which causes the data to be copied to the base (0 offset) of the > currently defined PBO. > > Of course, in pyOpengl this does not seem doable, as the buffers are > handled internally, and the last argument is not exposed. > Is it possible that we could have new versions of the affected calls > exposed that do take the last argument? > Perhaps a glReadPixelsB (for buffer) or something like that? > (glWritePixels has the same limitation). > > PBOs are a very important feature for using openGL in image > processing, so this would be a very useful addition. > > It would also allow glReadPixels to be used from python in situations > where the overhead of the double data copy currently required for the > (much easier to use) current implementation is too much whem moving > through bounce buffers. |