一个DirectX的Sample引发的学习（1）

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[align=left]这个例子描述了怎么使用D3DX的SHPRTSimulation，一个per vertex precomputed radiance transfer (PRT)的simulator。使用了low-order spherical harmonics (SH)并把结果记录到文件中。然后描述了怎么使用 clustered principal component analysis (CPCA)来压缩数据并在实时的arbitrary lighting的环境下使用vs_1_1 vertex shader来显示结果.[/align]
[align=left]虽然整个Sample的代码相对比较简单，但是背后的原理，却稍显复杂，至少对我来说，比较复杂，于是乎，查找了相关的论文，论文正在学习加翻译中，感觉受益匪浅。[/align]
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[align=left]参考的论文如下：[/align]

Sloan, Peter-Pike, Jan Kautz, and John Snyder. "Precomputed Radiance Transfer for Real-Time Rendering in Dynamic, Low-Frequency Lighting Environments". ACM Transactions on Graphics (TOG), Proceedings of the 29th Annual Conference on Computer Graphics and Interactive Techniques (SIGGRAPH), pp. 527-536. New York, NY: ACM Press, 2002.

Sloan, Peter-Pike, Jesse Hall, John Hart, and John Snyder. "Clustered Principal Components for Precomputed Radiance Transfer". ACM Transactions on Graphics (TOG), Vol. 22, Issue 3 (SIGGRAPH), pp. 382-391. New York, NY: ACM Press, July 2003.

Green, Robin. "Spherical Harmonic Lighting: The Gritty Details". Game Developers' Conference, San Jose, CA, March 2003.