Evan on Engineering Software

It's not being unfair to recognize that companies tend to act in their best interest.  Microsoft naturally wants software developers to focus on supporting Direct3D, rather than OpenGL.  So, would it be surprising to find that they'd built limitations into Vista that would "encourage" this?

In a new white paper from the Khronos OpenGL ARB Working Group, there is quite a bit of solid documentation addressing this question.

Here's a diagram, from the paper, showing how OpenGL is supported under Vista:

You'll probably notice that there are no differences in how OpenGL and Direct3D are supported.  The assumption that's implicit here is that an independent hardware vendor (nVidia, Intel, ATI, or otherwise) supplies the driver software shown in the bright blue boxes, and that it takes advantage of the OpenGL capabilities inherent in the graphics board.  Without this driver software, Vista will fall back to software emulation of OpenGL -- which is not a pretty thing.

Here are current benchmarks, showing relative OpenGL performance between Vista and XP:

Vista is not generally as fast, but it's in the same neighborhood.   It should get better, as the graphics card manufacturers fine-tune their drivers further.

So, does this all lead to the conclusion that Microsoft is going to play totally fair with OpenGL?

In short... no.   This is sort of a "so far, so good" situation, with no long-term guarantees.  It's still in Microsoft's best interest to push Direct3D.  It is only pressure from major application developers that has motivated Microsoft to continue providing good OpenGL support.