Referencesdocumentation
http://mathproofs.blogspot.com/2005/07/mapping-cube-to-sphere.html
http://mathproofs.blogspot.com/2005/07/mapping-square-to-circle.html
http://paulbourke.net/geometry/transformationprojection
https://github.com/rlk/envtools/blob/master/envremap.c
http://csc.lsu.edu/~kooima/articles/genperspective/index.html
http://mathproofs.blogspot.com/2005/07/mapping-cube-to-sphere.html
http://paulbourke.net/geometry/transformationprojection
http://en.wikipedia.org/wiki/Spherical_coordinate_system
http://math.stackexchange.com/questions/131735/surface-element-in-spherical-coordinates
http://en.wikipedia.org/wiki/Surface_integral
https://en.wikipedia.org/wiki/Field_of_view_in_video_games#Field_of_view_calculations
http://www.math.unl.edu/~scohn1/EngRevf08/surfaceint.pdf
https://kahrbjy.files.wordpress.com/2012/08/ee207notes3.pdf
http://mathworld.wolfram.com/SolidAngle.html
http://en.wikipedia.org/wiki/Solid_angle
Sampling-Efficient Mapping of Spherical Images http://mentallandscape.com/Papers_01spheremap.pdf
http://blog.xyzw.us/2015/01/the-trouble-with-wide-fov-rendering.html
https://twitter.com/casseveritt/status/549785345777074176
http://tutorial.math.lamar.edu/Classes/CalcII/ParaTangent.aspx
http://www.ltcconline.net/greenl/courses/107/PolarParam/tanlin.htm
http://www.nvidia.com/object/cube_map_ogl_tutorial.html
http://antongerdelan.net/opengl/cubemaps.html
http://www.learnopengl.com/#!Advanced-OpenGL/Cubemaps
http://www.euclideanspace.com/maths/geometry/elements/plane/lineOnPlane
http://www.cs.princeton.edu/courses/archive/fall2000/cs426/lectures/raycast/sld017.htm
https://www.opengl.org/discussion_boards/showthread.php/168009-How-to-get-the-horizontal-fov
https://en.wikipedia.org/wiki/Field_of_view_in_video_games#Field_of_view_calculations
https://wiki.unrealengine.com/Dynamic_Textures
https://forums.unrealengine.com/showthread.php?50349-Setting-Up-a-Dynamic-Texture
http://www.gamerendering.com/2008/10/05/bilinear-interpolation