Shadow Mapping
http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/
Cascaded Shadow Maps
http://msdn.microsoft.com/en-us/library/windows/desktop/ee416307(v=vs.85).aspx
http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html
Perspective Aliasing
http://www.cg.tuwien.ac.at/research/vr/lispsm/wimmer-egsr04-lispsm.pdf
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英文
http://en.wikipedia.org/wiki/Shadow_volume
http://developer.nvidia.com/object/doc_shadows.html
http://www.devmaster.net/articles/shadow_techniques/ （推荐！）
http://joshbeam.com/articles/stenciled_shadow_volumes_in_opengl/
http://mynameismjp.wordpress.com/samples-tutorials-tools/deferred-shadow-maps-sample/
http://home.comcast.net/~tom_forsyth/papers/papers.html
Fast, Practical and Robust Shadows.pdf
Improving Shadows and Reflections via the Stencil Buffer.pdf （推荐！）
中文
http://www.zwqxin.com/archives/opengl/shadow-volume-1.html
http://www.gamedev.net/topic/624209-should-i-use-slope-based-depth-bias/
http://msdn.microsoft.com/en-us/library/bb975671(v=xnagamestudio.31).aspx
http://developer.download.nvidia.com/SDK/10/direct3d/Source/VarianceShadowMapping/Doc/VarianceShadowMapping.pdf
http://http.developer.nvidia.com/GPUGems3/gpugems3_ch08.html
http://http.developer.nvidia.com/GPUGems/gpugems_ch11.html
http://msdn.microsoft.com/en-us/library/windows/desktop/ee416307(v=vs.85).aspx
Aliasing
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http://developer.amd.com/wordpress/media/2012/10/Isidoro-ShadowMapping.pdf
http://www.lighthouse3d.com/tutorials/glsl-core-tutorial/fragment-shader/