I seem to recall rumors that Starcraft 2 looked better when using DirectX 10 over DirectX 9. Is this true, and if so, can you give examples (preferably in screenshot form)?
As far as I know, StarCraft II quality is not increased by using DirectX 10 as opposed to DirectX 9. I think XP users can crank up all settings to ultra as well.
Maybe the reason for that rumor is a Blizzard FAQ from 2007 (emphasis mine):
Will StarCraft II take advantage of DirectX 10? What other graphical goodies are included?
The game will be compatible with DirectX 10, and we're still considering whether there will be exclusive DirectX 10 graphic effects, but the graphics engine will also be very scalable to ensure that a wide range of different systems will be capable of running StarCraft II. The new engine is also capable of rendering very large units, as well as large numbers of units on screen together. Havok physics have been integrated into the engine for added realism as well.
The official recommended system requirements, by the way, implicitly say DX10 is needed:
PC Recommended Specifications:
- Windows Vista®/Windows® 7 <-- these OSes come with dx 10
- Dual Core 2.4Ghz Processor
- 2 GB RAM
- 512 MB NVIDIA® GeForce® 8800 GTX or ATI Radeon® HD 3870 or better <-- these cards support dx 10
So I think that this seems to be an appropriate discussion to the site until you actually know the answer. The answer itself actually has nothing to do with gaming and is more appropriate for Game-Dev or SO than here. Unfortunately, I don't think I can convince you that this question is inappropriate without first giving the answer.
DirectX 10 has a demonstrably noticeable effect on Starcraft 2, unfortunately, it's not the sort of thing I can show you in a screenshot.
Starcraft 2 is one of the few games to have Pixel Shader 2.0 as a minimum requirement. For those of you unaware of what a Pixel Shader is, it is a programmable piece of the graphics pipeline that allows developer code to run on the GPU. These Pixel Shaders are usually used for such buzzwords as: Phong Shading, Bump Mapping, Volumetric Shadows... but they're actually a lot more basic than that as they're actually your fragment rasterizers (OpenGL even calls these Fragment Shaders).
Now you may be thinking: Wait a sec, Pixel Shader 2.0 debuted on DirectX 9, not 10. So why are we talking about it?
Since Starcraft 2 requires Pixel Shader 2.0, more advanced effects provided in Pixel Shader 3.0 and 4.0 (DirectX 9c and 10, respectively) have to be reconstructed in Pixel Shader 2.0 and, as a result, have a much poorer performance time (i.e., are slower) and will set back your frame rate. By comparison, these artifacts provided in Pixel Shader 4.0 will run smoother. However, if you provide Pixel Shader 2.0 code to run on Pixel Shader 4.0, you will actually see a decrease in performance as compared to native code.
So what does this mean for me as a Gamer?
Nothing. If you were a game developer or a graphics programmer, this is a really interesting conversation about trade-offs in performance as compared to the user base and how trying to satisfy everyone can end up with a poorer overall product, but you don't care about any of that because this is a gaming website. Much like a programmer doesn't care about trade-offs in monitors, he only cares about which one he's running on.