There was an issue caused by Antialiasing being done after DoF. Move TAA
after DOF and Motion Blur.
Also certain pixel with lower CoC would be spread all over the background
because the neighbooring pixel have higher CoC. So we need to apply some
bilateral filtering when downsampling. Currently we limit the influence of
neighbor pixels with a CoC inside the range [MaxCoC-2, MaxCoC].
This means only one texture to draw to and only one sprite per pixel.
The texture is twice as large and near and far planes are side by side.
The sprite choose the biggest coc to expand to and is redirected to the
area (layer) it belongs to.
The fragment shader discard every pixel that does not belong to the correct
layer.
Due to the scatter operation being done at half resolution, undersampling
is visible at bokeh shape edges (because of the hard cut).
This commit adds a smoothing function to minimize the problem.
Also optimize the bokeh shape parametrization by precomputing a lot of
constants.
This new blending allows background to fill the gaps left by forground
objects. However this has a drawback, background objects that should be
partially occluded in this case can be seen through the blurred objects.
This does not fix the problem of blurred foreground over sharp background.
Also cleanup code to be simpler and remove unused geometry shader.
This was cause by some post process not always sampling the highest mipmap.
But if there is no need for mipmapping (i.e. no SSR) these levels will be undefined.
So forcing all Post FX shader to sample level 0 fix this.
