[Bf-funboard] Proper soft shadows in composer

[toontje at telbonet.an]

I would like to see the shadow pass Z-valued. Every pixel in the shadow
area should have the information what the relative distance is from the
lightsource(s) to the object(s) that is causing the shadow. That way, I
think, you can feed this information into the defocus node. The result
should be the same as raytraced soft shadows (sharp near object and blurry
far from the object). The other aspect is that the blurrier the shadow
gets, the less intense it is. But that is not a problem because you can
stack alpha on the very same z-values.

I wonder why this was never coded into Blender, since I think this is the
cheapest way (render time and coding) to achieve this.