Postprocess renderer

[Witek902]

Post process renderer should be elastic, so adding a new effect is easy and does not require copy-pasting tones of code. There should be something like "Pass", which would hold:

• input and output textures
• shader
• post process parameters (bounded with the shader)

TODO:

• [ ] customizable posprocess effects order
• [ ] effect parameters and order should be easy to modify from application's level
• [ ] effects:
  • [ ] color correction and tone mapping
  • [ ] AA-filter
  • [ ] bloom
  • [ ] blur
  • [ ] depth of field (http://ivizlab.sfu.ca/papers/cgf2012.pdf)
  • [ ] resampling
  • [ ] camera effects: distortion, chromatic abberation
  • [ ] lens flares
• [ ] calculation of average scene luminance from previous frame
• [ ] applying effect only to a region of a texture