DirectX 10 not backwards compatible?

[Catweazle]

The next version of Microsoft's graphics API DirectX will definitely be different to its predecessors. To be included in the upcoming Windows Vista, DirectX 10 will be the programming interface previously called Windows Graphics Foundation by its developers.

Those people who follow developments in PC graphics hardware will quickly realise that DirectX 10 is designed for the future. Accomodation for graphics 'features' such as Shader Model 4 and higher shows clearly that the programming interface will cater to graphics hardware not even produced yet. But according to news site The Inquirer, at the Games Developers Conference in Europe Microsoft has informed developers that DirectX 10 will 'cut' backwards compatibility with titles written for DirectX 9 and earlier! Those titles will still be able to be run on the system, but will need to run via an additional software 'layer'. It is a fair assumption that titles running via software will operate more slowly.

If this proves to be correct, of course, it will make Windows Vista less appealing than previously to those people who wish to run their existing library of 3D titles on exisiting machines.

[jwenting]

It's not really any different from running DX7 games on a DX9 installation.
The calls are different so there's another entry into the HAL that's used.
I doubt another software layer needs to be added, and if it is I doubt you'd notice the difference unless your system is already marginal at playing the game in question as the added calls would be CPU calls rather than GPU calls and most games nowadays are far heavier on the GPU than they are on the CPU.
As an example: I noticed no performance improvement on most of my games when switching from a 1.6 to a 2.4 GHz CPU while keeping the same videocard, only when upgrading that as well did I see a marginal improvement and that mainly in display quality rather than speed.

The whole thing sounds to me like a prelude to another round of Microsoft bashing, preparing for the claim that "Microsoft is trying to drive game manufacturers out of business by preventing their games from running on Vista".

[benna]

I'm honestly not much of a gamer, but this doesn't seem all bad to me. Microsoft has a bad habbit of maintaining backwards compatiblity when it shouldn't. They claim to innovate but usually their hands are tied by backwards compatiblity.

I have heard that Vista might only support OpenGL through emulation with DirectX 10. That would be stupid. I know microsoft loves to do everything it can to maintain its monopoly, but I think this would only serve to piss people off, and decrease performence unnecessarily.

One area I wish microsoft wouldn't maintain backwards compatiblity is with their "features" that break web standards. They implement "standards" before they become standards, and then they don't become standards, and it fucks up compatiblity for all the other browsers. They need to stop doing that.