   DirectX 9 in vista?
  Hi,I was just wondering is it possible to program in a direct x 9 sdk under vista while keeping directx 10 install or will I have to roll back to directx 9?If I have to roll back can I do so under vista? and if you know exactly what to do that'd great.Thanks   
  As I know you can not roll back directx in windows and you can’t install dx 9 sdk under vista. I wrote a dx application in dx 10 and it doesn’t work under xp, even I didn’t change any code and just compile it in dx 9 in xp and then another compile in dx 10 in vista. It didn’t work in xp anymore. It needs dx 10 installed and this version can not be installed in xp;  Yes^.There are 2 versions of Direct3D9 on Vista. One is Vista only, and one is the usual D3D9 from before. There is no difference programming DX9 on Vista than there was before, just get the latest DX SDK, and use the DX9 interfaces. Doesn't matter that you have DX10 installed, you have DX9 too.   ;  So much confusion...1) There is no DirectX9 SDK. The DirectX SDK currently includes both D3D10 AND DirectX9. You can use either with the same install of the SDK.2) Any version of DirectX, since forever, has had backwards compatibility. Just like you can run DirectX3 software on your Windows XP with DirectX9c installed, you can run DirectX3 software on Vista with DirectX10 installed. You don't need to uninstall anything.3) Vista adds a new API called Direct3D9Ex. This adds some Vista only features to DirectX9, by allowing you to query for support from your application. I think DirectX9Ex is also currently included with the DirectX SDK, so if you want to use that, you don't even need to download anything.Hope this helps.   ;  well the thing is i'll be switching between two computers one with vista and one with xp doing direct x programming on both.. will there be problems in doing so.. or is it simply a matter of not calling certain functions that relate to direct x 10 to ensure the code works on both?   ;  Just keep using the Direct3D9 interface and you'll be fine.   