Originally published at ScummBlog. You can comment here or there.
So I have hit a snag with Windows Vista. Not a huge one, but a snag nonetheless.
Windows Vista does not properly support OpenGL. I had been using the -opengl switch with World Of Warcraft to get better frame rates out of Windows XP, and assumed the same would happen under Windows Vista. This is not the case.
A little back story about Microsoft and OpenGL.
All previous versions of Windows that “support” OpenGL have basically an old, crippled version by default running independently of DirectX. OpenGL 1.4 without extensions is what MS packages with Windows. The good part is that ATI and Nvidia add an OpenGL driver with their installs, so games and programs can use the current OpenGL 2.0 with extensions.
With Windows Vista, MS is having OpenGL run on top of DirectX 10. This is reducing the performance of OpenGL by as much as 50% (by some estimates.) Microsoft hasn’t shared any information to ATI and Nvidia on how to override this default OpenGL so they can have a separate OpenGL 2.0 driver for programs to use.
By removing the -opengl option from World Of Warcraft, I increased the frame rate by quite a bit.
It’s a bit of an underhanded move, forcing any 3D program under Vista to use DirectX for the best performance. Hopefully MS will allow a 3rd party OpenGL 2.0 driver to be installed.
I found the following in the abstract for the current Nvidia ForceWare Drivers for Windows Vista x86:
* These drivers are tested for use only with Microsoft Windows Vista Beta2 only. Click here to download Windows Vista Beta 2.
* Includes OpenGL driver for compatibility testing.
So hopefully they get the OpenGL drivers in better shape for better performance!