Well, as most people probably already know by now, Steam for Mac went live yesterday. The cool thing about Macs is that via Bootcamp, you can run Windows on the same hardware, so these Steam games allow for direct performance and image quality comparisions between OS X/OpenGL and Windows/Direct3D.
Anandtech did a nice article on this. In my previous blogs I already wrote how I struggled to get the performance of my OpenGL code up to Direct3D standards… and in a way it’s good to see that Valve has the same problem. This gives my earlier claims more credibility, and at the same time, I am more confident that the performance problems weren’t just caused by problems in my own code.
What I did not quite expect though, is that the Mac version of the games also looks considerably different. It looks like HDR rendering is just missing altogether, as various bright areas in the Windows screenshots have a rather bland appearance in the Mac version. And they used a GeForce 285, which should have excellent OpenGL support, so that can’t be it. nVidia is the best choice for OpenGL. So I wonder why the lighting is so different. It should be possible in OpenGL just fine.
But there you have it… there still is quite a big gap, both in performance and image quality, between Windows/D3D and OS X/OpenGL. Having actual OpenGL ports of games makes it harder for the OpenGL/non-Windows crowd to sustain that there is no advantage to Windows/D3D as a gaming platform, and other solutions are as good or better.