Flachmatuch said:
@dLMN8R: My point is that the reason it doesn't work is to make you buy a new OS, not because it'd have been so difficult or costly to do, but whatever.
You're only half-correct.
DirectX 10 and Shader Model 4.0 are actually distinct things. You can use geometry shaders and whatnot in XP using OpenGL. Not exposing SM 4.0 features to DX9 (an hypothetical DX9.0d) could be considered a move in locking features to Vista to "incentive" users to move on.
However, DirectX10 brings much more than merely SM 4.0. Most significantly, the way it handle resources changed a lot and is relies entirely on the new driver architecture.
Example:
In XP the video memory was something completely off-limits to the OS and was handled entirely by the GPU drivers. The drivers were responsible (and not obliged) to implement support for handling multiple 3D applications running simultaneously, or paging resources from VRAM to RAM when running out of the former.
In Vista/7, VRAM is an OS-managed resource. Most of the VRAM management is made by the OS, not by the drivers, which are only required to expose a much more sane interface.
Due to this, games can do things like loading a texture straight from disk to VRAM without having to a copy in RAM in case the GPU goes out of VRAM or when the 3D context needs to be re-created (aka: changing resolution, alt-tabbing, etc). The OS will automatically move the texture from VRAM to RAM, or even to disk, and back, if necessary. This simplifies code by a huge lot, allows faster load times and is a god-send for games that do streaming in real-time (Just Cause).
When porting a game from 360 to PC, it is much easier to use DX10 than DX9, because the 360 DirectX works much more like the former, despise it having a DX9-class GPU. There are even some 360 features that have no correspondent in DX9, but do in DX10.
But I agree that MS makes buying a new OS a bigger pain than it should be. Windows is expensive and their upgrade paths are absurdly limited. They have zero regard for those who build their own PCs.
. Anyone feel like testing this on the demo? I'm wondering that if dxdiag thinks you have Dx10 would it work on games no one made a patch for like Stormrise?
