https://bugs.freedesktop.org/show_bug.cgi?id=29850
--- Comment #5 from Marek Olšák maraeo@gmail.com 2010-09-11 09:19:09 PDT --- The problem is:
Mesa: User error: GL_INVALID_OPERATION in glDrawBuffer(buffer=0x405)
That's why nothing is drawn to the main framebuffer. We should get alienarena people to fix this in their code.