Microsoft details DirectX 11: shader model 5, hardware tessellation, multithreaded computing
DirectX 11 – the one sure thing you’ll want as soon as Windows Seven ships to shelves a few years from now. Revealed back in Gamefest 2008, DirectX 11 turned heads with its venture into multithreaded computing territory and support for using shader processors as additional processing power. Today, however, Microsoft‘s Kevin Gee detailed what the software engineers at Redmond had planned for the API, and we’ve compiled a summary at the full story.
Taking a step forward, Microsoft planned to not only improve in hardware rendering with the recently announced DirectX 11 API, but also expand the way software engineers could get their programs to work efficiently on modern computer hardware.
Upon reflection of the special feature by Kevin Gee of Microsoft (by way of Gamasutra’s XNA portal), Microsoft plans to dive into the mechanics of multiple core and multithreaded computing by way of lower level hardware support.
Communicating with the computer hardware at the “down-level,” DirectX 11 is expected to serve as the Windows Display Driver Model (WDDM) of the next Windows, just as DirectX 10 was to Windows Vista.
But unlike DX10, DX11 introduces a “no break” in-between the current generation API, in the same manner that DirectX10 introduced a discontinuity from DirectX 9. As announced before, DirectX 11 will be backward compatible with DirectX 10 hardware and supporting operating systems.
This would mean that Windows Vista and DirectX 10.1 hardware will be able to handle DirectX 11, though Gee confirms that the next generation application programming interface will release by the time the next Windows operating system ships to shelves as well.
In DX11, programmers will be able to streamline engineering of software for multi-core and multi-CPU computers. This is because Microsoft plans to not only implement rendering contexts (processing scheduling) and deferred contexts, but also asynchronous API calls.
This asynchronous system extends to communications and transactions between a multi-core CPU and a GPU, or a multi-core CPU and a multiple-GPU card, which either option would heed the instructions as listed by the primary immediate context and the added deferred contexts.
In addition to that, DX11 takes the idea of general purpose GPU processing and mixes in cross-hardware support. Regardless of graphics chip manufacturer, all modern GPUs with shader processors can be used for helping in processing applications.
But for graphics powerusers and game developers, perhaps the most interesting feature that DirectX 11 has planned for implementation is the inclusion of hardware tessellation. Microsoft’s engineers introduced three hardware stages for the rendering pipeline that will allow high power GPUs to perform tessellation over hardware: the hull shader, the tessellator, and domain shader.
With DX11 also comes new texture compression methods BC6 and BC7. Microsoft boasts that these two compression formats are the best they can offer for the ratio of high-quality over performance.
Block compression 6 (BC6) compresses high dynamic ranging (HDR) data at a ratio of 6:1, given hardware support for decompression. BC7 offers 3:1 compression ratios for 8-bit low dynamic range (LDR) data.
DirectX 11 also introduces Shader Model 5 for High Level Shader Language (HLSL), providing a better way graphics programmers will be able to implement shader programs. It also adds double-precision support, which allows programmers to tackle shader specialization with polymorphism, objects, and interfaces.
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Via Gamasutra