I just got news that Velvet Assassin has been ported over to the Mac and is available on the App Store! However, I was not at all involved in the Mac port and I don’t know the developers who did—it came as a surprise to me as to anyone else in the former team. Here is a direct iTunes link: (EDIT, no longer available as of 2021, unfortunately)
Shader Bug on ATI graphic cards
Unfortunately there is a shader bug with ATI graphics chips. It happened to me while trying it out on a 2011 iMac with an ATI Radeon HD 5670. I got reports from friends that this is not a problem of the Mac port itself but it happens on PC too. The problem is related to ATI chips with drivers that are newer than 2010 or so. Here is a screenshot:
It is good to see how physically based shading is finally gaining momentum in real time graphics and games. This is something I have been advocating for a long time. Developers are spreading the word. I was especially surprised to learn about Call of Duty: Black Ops joining the club . Even a slick 60Hz-shooter with no cycles to spare can afford to do PBS today!
This leads me to the topic of this post, the normalization of the Blinn-Phong specular highlight. Why am I writing about it? It came to my mind recently with the current batch of publications from people adopting physically based shading models. This got me checking the maths again and I compiled a list with normalization factors for different shading models, given here in this post. I would also like to elaborate a little on the model that I wrote about in ShaderX7 . Be aware this post is a large brain dump.