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This is sort of old news, but I couldn't find anything posted about it (and I found out about it today) so...

Slashdot, The Inquirer and others point to the discussion at the OpenGL boards, here.
Also: Wikipedia

Basically, MS has decided to not let OpenGL have direct access to the hardware, but instead layer it through their DirectX 10 (through which also earlier versions of DX will be layered. Apparently, DX will also no longer be backwards compatible). In other words, OpenGL will be emulated through DX10, which is bound to affect performance badly. Some guy from 3Dlabs writes:

Barthold wrote:This information came from the OpenGL BOF held at Siggraph 2005 in LA this last Wednesday evening. This was confirmed at the BOF by NVIDIA, ATI and us (3Dlabs).

As soon as an ICD is loaded the composited desktop is turned off on Windows Vista. If you want the composited desktop Aeroglass experience, you will need to make your application go through Microsoft's OpenGL implementation, which is layered on top of DirectX. As pointed out earlier, this layering can have performance implications. Their implementation supports OpenGL version 1.4 only, without extension support.

We believe it possible to provide an ICD with full composited desktop support while adhering to the stability and security requirements in Windows Vista. But we need Microsoft's help in doing so.

For some more information, you can browse these Microsoft Winhec slides:

"Windows Graphics Overview [WinHEC 2005; 171 KB]"

"Advances in Display and Composition Architecture for Windows [WinHEC 2005; 422 KB]"

Regards,
Barthold
3Dlabs

It later in the thread at OGL forums turns out that it would probably be possible to use OpenGL with full hardware support, but only by disabling some features of their new OS, or possibly running in fullscreen mode. DirectX would have no such limitations.

As Mr. Barthold writes, it would be possible to have full OpenGL hardware support, with extensions and everything, and also all of the Vista effects. But only if MS would let the developers have the information they need to write the appropriate drivers. It seems that MS show no sign of wanting to do that (surprise, surprise).


Now, it should be mentioned that Microsoft support for OpenGL hasn't been updated since Windows95 and OpenGL 1.1, but it has been possible to circumvent this through the use of extensions. If MS decide to use the DX layer thing, this would no longer be possible, as any extensions not included in the OpenGL 1.4 standard (which would then no longer be extensions, but anyway) would not exist in the DX-OGL framework.

So the question is, why is MS doing this? What possible good could come out of not letting the most used standard in 3D graphics be fully supported in their new OS? It is not exactly going to make engineers (whose CAD programs and similar almost exclusively uses OGL), 3D modelers and animators (Maya and most other such tools also use OGL) and many others drool over the new Windows. It makes just as much sense as their decision on Java support in MSIE way back when (ie, none at all). It seems like they can't stand cross-platform standards. They really have to control everything.

I wonder if Sony's announcement that PS3 would have some support for OGL could have something to with it...

Yeah, saw it a while ago. The articles I saw said it would reduce performance by "as much as 50%".



Why?

Macs use OpenGL- Linux uses OpenGL- PS3 uses OpenGL- and I'd assume Nintendo uses OpenGL because I really doubt they use DirectX and I don't know of any others.

XBox 360 uses DirectX.

By making it a disadvantage to develop for OpenGL, Microsoft forces developers to use DirectX. By forcing developers to use DirectX, that makes it hard for them to port games to Mac/Linux/PS3/Revolution and easy to port games to XBox 360. It also means the Mac/Linux ports will have bad performance as always. Right now the primary reason most people don't switch to Mac OS X and Linux is that Windows has all the games after all; MS wants to keep it that way.

At least, that's my guess.

Essentially, in order to use Avalon's 3D-accelerated mode and OpenGL at the same time, you'd have to ensure that your GPU can process D3D and OGL code simultaneously. That's not exactly an easy task, though 3DLabs seems to think they can do it.

The "emulation" layer is probably a sensible way to do this - and how many windowed applications (outside the professional world) use OpenGL anyways? If you do need it that much, you probably don't care about if Avalon's advanced features are turned off. Certainly, most games are run fullscreen.

OpenGL wrappers which redirect to DirectX which exist today dont really give that much of a preformance hit.

Also one of the reasons OpenGL is being neglected by Microsoft is the entire screen composing layer can not work when OpenGL is being used. Which makes Windows look "bad" which reflects on Microsoft not the shitty app doing it.

And Mac OS can get away with OpenGL because the entire system is based on it for the rendering system. Windows has a different approach

Isn't openGL handled entirely by the graphics driver currently?

Currently on Windows the Graphics card vender needs to write a driver for DirectX+GDI(aka rest of windows), and a driver for OpenGL.

It isnt a very desirable situation.

Why do I have this nagging feeling that this will backfire?

I guess this is one way for Ati's opengl support to improve

Davis 51 wrote:Why do I have this nagging feeling that this will backfire?

About actually trying to elaberate how it would backfire? "The SKY IS FALLING" claim really works much better when you can show it.

As Praxis said, it does seem to be made to drive away third party support from the PS3/Revolution/Mac/Linux. If the X-Box 360 is the ONLY console of the three to use DirectX, and Windows is the ONLY Operating System to shun OpenGL, then, I believe that this will drive support away from Microsoft. It's 2 against 1 on the consoles and 2 against 1 on the PC.

Davis 51 wrote:...and 2 against 1 on the PC.

Yeah, a lot of developers will shun Windows in favor of developing for the millions of OS X/Linux gamers.

The problem is that it's 2 with 5% marketshare vs 1 with 90% marketshare.

Praxis wrote:The problem is that it's 2 with 5% marketshare vs 1 with 90% marketshare.

Well, not so much of that with the PC platform as with the Console platoform.
I doubt that they hold 90% of the Console Market.
If they do succede, then that will suck bigtime.

I hope graphics art and design companies that rely a lot on OpenGL will come out and have a say about this. Hopefully the likes of Autodesk, Avid, and Adobe may have the balls to stand up to Microsoft, assuming the continued reliability of OpenGL is in their interests.

Davis 51 wrote:

Praxis wrote:The problem is that it's 2 with 5% marketshare vs 1 with 90% marketshare.

Well, not so much of that with the PC platform as with the Console platoform.
I doubt that they hold 90% of the Console Market.
If they do succede, then that will suck bigtime.

Hehe! There are far bigger problems than the graphics API when it comes to porting between consoles. The PS3, Xbox 360 and Revolution all will have different SDKs, have different graphics chips and different CPUs (even if they share some elements between them, code built for one CPU is not going to automatically run on the other).

Shinova wrote:I hope graphics art and design companies that rely a lot on OpenGL will come out and have a say about this. Hopefully the likes of Autodesk, Avid, and Adobe may have the balls to stand up to Microsoft, assuming the continued reliability of OpenGL is in their interests.

Why? MS isn't dropping OpenGL, and for their purposes, the emulation through DirectX when using the 3D desktop should be more than enough.

IIRC, this is actually MORE support for OpenGL than what MS has done in the past. They used to just let the graphics vendor deal with it.

skyman8081 wrote:IIRC, this is actually MORE support for OpenGL than what MS has done in the past. They used to just let the graphics vendor deal with it.

Not quite true. They do have an OpenGL 1.1 implementation in all versions of windows since 95 but considering how out of date that is you're almost totally right. You have to use extensions for pretty much every vaguely modern part of the API on windows. It's a little irritating but in the end isn't all that big a deal really. Just an inconvenience.

Anyway I'm going to hold judgement on this till we have a final copy of Vista in our hands. There's always too much bullshit flying about when people talk about new versions of windows to make a good judgement, IMO. Remember all the crap about how XP was going to be some sort of evil DRM monster or something because of the activation?