- Add noise to remove undersampling artifact
- Create 2 mipmaps to the scene color buffer in order to have bigger blurs
- Replace blur2 with a 3x3 median filter that doesn't dilate the highlights
- Use temporal accumulation to remove noise
For some reason all of this exacerbate some bleeding issues happening on
far foreground elements from near foreground elements. The actual problem
was already happening before but was not really noticeable. It needs some
more work to be fixed.
- Compute samples positions on CPU.
- Use 3x3 Box blur instead of 2x2.
- Implement bokeh parameters.
With this commit, dof performance is almost negligeable.
The quality is a bit lower than before but can be improve. Also now big
Circle of confusion are supported (up to 200px).
Cost is ~1.25ms on AMD Vega with a 2560p viewport than full HD and
pretty shallow depth of field.
Coc downsampling and dilation is not used anymore for now (commented).
The algorithm used is borrowed from :
http://tuxedolabs.blogspot.com/2018/05/bokeh-depth-of-field-in-single-pass.html
This makes it possible to have a decent blur for foreground over defocused
background in one pass only.
The algorithm is using a gather approach that is much faster
than the scatter approach used in Eevee. This makes it possible to have
custom bokeh shapes (not implemented yet) which would be impossible with
a separable gaussian technique.
The blur is done in 2 steps. The first one define the shape of the bokeh
and the second that fill the undersampling.
A downsample max-CoC tile texture speed up the gathering process.
