Added Cook-Torrance shader model
Added a scene to create Beckmann texture procedurally
Added SpecularDistribution texture and roughness parameter to CookTorrance shader
Changed the wrapmode of the Beckmann texture
Fixed the Beckmann conversion bug
Include lightColor to calculate the specular term in CookTorrance
Fixed the bug in creating the Beckmann texture and added its fast version
Fixed the bug in calculating the geometric attenuation factor of Cook-Torrance model.
Make the Cook-Torrance shader obey energy conservation
Renamed CookTorrance to TorranceSparrow
Merge pull request #16 from sindharta/cook-torrance

Torrance Sparrow