Carl Edlund is a Software Development Manager at ACES Studio, the internal Microsoft Games studio producing the big tenth major installment of Flight Simulator. Vista was originally scheduled to ship late this year, around the same time as Flight Simulator X so the title was always planned to be somewhat of a showcase for the new operating system's focus on games, and that includes DirectX 10.
ExtremeTech: What is DX10 allowing you to do in Flight Simulator X that you couldn't do simply with a more powerful DX9 card?
Edlund: DirectX10 not only allows you to get even more of the advanced graphics features, at an even better performance, but as part of the Unified Driver Model, the Memory Manager and Scheduler on Windows Vista create a far superior user experience. Games will be able to provide multiple 3D view windows at the same performance of a single DirectX 9 window. By shifting more of the graphics processing tasks to the graphics hardware, the CPU is freed up to focus on other gameplay related tasks like better AI, more in-scene entities and deeper physics, thus enabling entirely new gameplay experiences.
ExtremeTech: It seems like nobody has actual DX10 hardware yet. Are you doing most of your work in the DX10 reference rasterizer? Simply making more complex shaders along a DX9 code path? "Render to spec" work in a program like 3ds Max or Maya? Exactly what methods are you using to do DX10 development at this point?
Edlund: At this point, we are ensuring that the abstraction layer between the game and the graphics calls are clean and that we can swap in the DirectX 10 pipeline with minimal impact to the game engine itself. We have worked extensively with the DirectX 10 SDK, the DirectX 10 team and the hardware manufacturers to create a detailed plan of what features we will be taking advantage of and how we will integrate the code and art assets into the product pipeline.
ExtremeTech: Last we heard from you, Flight Simulator X would ship with merely DX9 support, and then a DX10 patch would be offered later. How soon after the January launch of Vista do you hope to release this patch?
Edlund: Yes, this is our plan. We are currently polishing and tuning our DirectX 9 pipeline to provide as detailed and smooth an experience as possible. When DirectX 10 hardware becomes available, we will create a parallel effort to port onto DirectX 10 and implement the feature extensions. We still plan on having this available at the time of Windows Vista launch.
ExtremeTech: DX10 is coming really late in the project for your game, so there's only so much you can do with it. Could you discuss some of your plans to possibly further exploit DX10 in future expansions or the next version of Flight Simulator X?
Edlund: Integrating DirectX 10 into our application will allow a much richer and more detailed world to be rendered at equivalent frame rates. Over the next releases, we will be continuing to increase the level of realism, detail in the world and world objects, dynamic lighting and subtleties, weather effects, and extending the capabilities of user interaction, exploration, and camera control in our world-spanning rendering environment.
ExtremeTech: In your own words, why should gamers care about DX10 and fork over the money for a hot new DX10 card when they come out?
Edlund: The performance and increased visual detail alone should be enough to make you run screaming to get the new cards. DirectX 10 will allow developers to take advantage of more of the DirectX 9 functionality, in addition to the new DirectX 10 features, to create more realistic scenes, not just showcased objects, then ever before possible. Supporting this is a more stable and coherent driver architecture that will end the days of driver crashes interrupting your game experience. By freeing the CPU up to do more game-related processing, you will see a quantum leap in the depth of AI, physics, character interaction and realism that becomes inherent in the next generation of games.
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Just for comparison:
What 'Glacier Park' looks like in Flight Simulator 2004
What that same scene will look like FSX under DirectX 9...
And what the same scene could look like FSX under DirectX 10... (it's just a render but
) 
Just for comparison... a photo of the scene (aka the Windows Vista desktop)
