My PC is running Vista Premium, and a few weeks back, I installed the GeForece 8600 GT, but I only have DirectX 9.0c. I thought 10 came with Vista?

Yes Vista contains Direct3D 10 and your new card is Direct3D 10 compatible.

How have you tested what Direct3D version you have available?

 

if you have a card that supports DX10, it will work with games that ask for DX10.  the DX9 and DX10 drivers are separate, and Windows Vista only uses DX9. 

David "LetsKillDave" Weller:

if you have a card that supports DX10, it will work with games that ask for DX10.  the DX9 and DX10 drivers are separate, and Windows Vista only uses DX9. 

Question, why isn't DirectX9 installed by default?
I know DirectX9Ex and DirectX10 is, but that doesn't allow support for legacy applications.

There's a lot of aspects about Vista that confuse me. It's like some things have been done deliberately decided to prevent back-compatibility. Good example is jscript.dll and vbscript.dll used by almost every .msi installer aren't registered by default.
The adverage user doesn't understand that these even exist or this could be an issue. To me seems silly.

Was Vista actually ready for the public?

Raven:

Question, why isn't DirectX9 installed by default?

I know DirectX9Ex and DirectX10 is, but that doesn't allow support for legacy applications.

Vista supports all previous DirectX versions. There may be some compatibility issues in cases of extreme API usage but general “legacy” DirectX applications runs fine. Most times I see a game failing on Vista the copy protection from the game was the reason.

Demirug:

Raven:

Question, why isn't DirectX9 installed by default?

I know DirectX9Ex and DirectX10 is, but that doesn't allow support for legacy applications.

Vista supports all previous DirectX versions. There may be some compatibility issues in cases of extreme API usage but general “legacy” DirectX applications runs fine. Most times I see a game failing on Vista the copy protection from the game was the reason.

This is true for DirectX9 applications, post installing of the DX9 RTM. There are only a handful that don't run, although I've found from time to time intense usage of the system prior to using DirectX will cause it to fail loading up properly. Applications will have a habit of initialising then immediately dropping to desktop, and remaining there. This is an issue with a large number of games where *everything* that happens outside of the game will cause it to drop back to desktop.

I fear that they didn't really test DirectX9 fully, as when I'm using or developing something in fullscreen I don't want it to drop back to desktop until the application closes or the user hits Alt-Tab (even then I prefer to override this feature).

Although I do wish I could say this same compatibility is true going futher back. DirectX8 applications are a gamble, and DirectX6/7 will often just refuse to run outright. Some I've learnt copying D3DRM.dll to their root directory solves this (if it's put in System32 it seems to want to call incompatible libraries), but that's only a handful of games this works for.
Dark Forces 2 - Jedi Knight is a good example of while the api will run the app there are serious issues as the entire screen will remain black no matter what you do.

I've actually dishearteningly found that Linux using Cedega actually runs DirectX8 and below with far better results than Vista. This just shouldn't be happen, either they should drop support for these applications out-right or fix the issues.

I'm also extremely disappointed under Vista the performance of DirectX. I would've hoped and had heard rumours during Vistas' development that DirectX would be able to run similar resources for fullscreen applications that you would expect from Xbox 360 Dashboard, but unfortunately that just isn't true. As for DirectX10 performance goes, I'm still not sure what to make of it. Annoyingly given it's only the next generation cards that won't be common until next year it makes it fairly pointless to develop for past personal interest or along side a DirectX9 engine. More to the point DX10 is realistically only Direct3D 10, DirectSound, DirectPlay, etc. are all still previous versions of deprecated.

Replacements and/or updates for these systems, really needs to be developed to maintain the completely rounded solution that DirectX has provided in the past. Only XNA itself seems set on providing this, but there is no native equivilant nor is the solution complete yet.

Something that I'm very interested to know is why have Microsoft dropped support in DirectX10 for non-DX10 Compliant cards? Previous DirectX incarnations were capable of being compatible, and using the features in that API that they support.
Although given there is no longer a fixed function pipeline, sure it wouldn't break DirectX10 by opening it up for Shader 1.1-3.0 compatible cards? Shader 2.0-3.0 in particular are the most common cards currently used and probably will be for the next few years given compatibility with the Xbox 360 which uses a Shader 3.0 GPU. To me it'd make sense for support for these cards so that everyone could take advantage of this performance increase in DX10.

Maybe I was just expecting too much from Vista.

Something that I'm very interested to know is why have Microsoft dropped support in DirectX10 for non-DX10 Compliant cards? Previous DirectX incarnations were capable of being compatible, and using the features in that API that they support.
Although given there is no longer a fixed function pipeline, sure it wouldn't break DirectX10 by opening it up for Shader 1.1-3.0 compatible cards? Shader 2.0-3.0 in particular are the most common cards currently used and probably will be for the next few years given compatibility with the Xbox 360 which uses a Shader 3.0 GPU. To me it'd make sense for support for these cards so that everyone could take advantage of this performance increase in DX10.

It was never dropped - it was never even an option. There are so many new hardware requirement for DX10 that backwards compatbiliy was probably impossible. Its not as simple as just handling old shaders.

MS, the card vendors and the major game producers felt that it was time for a clean start, free or the millions of CAPS issues and to standardize on card with a fixed function set. MS took the opportunity to revamp the API and remove some of the stuff that has been hanging on for many years.

It is interesting to be able to run a certain subset of D3D10 functionality on D3D9 cards in order to simplify development and leverage the new API. You likely won't see a performance increase though, since it's still running on the same DDI. Any perf increases would simply illustrate somewhere the programmer was inefficiently driving the D3D9 API. In any case this would strictly be a convenience for developers, and as such didn't take priority over the development of D3D10 itself. There has to be a tangible benefit to Microsoft for us to justify spending resources on this, and that was not the case in Vista because everyone who had a dependency on D3D10 already knew how to drive the D3D9 API as well or in most cases already had a D3D9 path implemented.

I agree with you John that add support for older DDI to the D3D10 runtime would not buy you any speed improvements. To make the developers happy supporting the WDDM interface for D3D9 wouldn’t be enough anyway.  You had to add the Windows XP DDI too and therefore make the runtime Windows XP compatible. I can understand that there was no budget for something like this in the Windows XP support pool.

Bu if we talk about a convenience for developers I believe we should talk about Direct3DX too. DXUT already contains some unification for D3D 9 and 10. Why not take this to the next level and build a D3DX API that support everything from SM 2 to 4 with a common Direct3D 10 based interface? I have played around with a prototype for this and it simplifies the development of mixed Direct3D9/10 applications.