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PRT

Jun 9, 2014 at 7:56 PM
Another scenario supported by the original D3DX9 library is Precomputed Radiance Transfer (PRT) and the associated simulator. These were not carried forward to newer D3DX editions and continue to only be available the legacy DirectX SDK's D3DX9 library. The shader-side use of PRT is reasonably easly to port to DirectX 11, but the offline building of the Spherical Harmonics (SH) data is not.

The SH math and the cubemap projection functions are available on my blog, but this is only a small part of the PRT story.

For anyone interested in the details of the algorithms embodied in the legacy D3DX9 library, here are the original papers

Peter-Pike Sloan et al, "Local, Deformable Precomputed Radiance Transfer", ACM SIGGRAPH 2005 Proceedings

http://research.microsoft.com/en-us/um/people/johnsny/papers/ldprt.pdf

Peter-Pike Sloan et al., "Precomputed Radiance Transfer for Real-Time Rendering in Dynamic, Low-Frequency Lighting Environments" ACM SIGGRAPH 2002

http://research.microsoft.com/en-us/um/people/johnsny/papers/prt.pdf