2D soft shadows

Hi!

I’m in the process of creating the light engine for my LibGdx project. I’m using box2d’s raycasting to build a light mesh (it is show on the picture).

http://s12.postimg.org/c63r2b7m5/help.jpg

With this method though I can only create hard shadows and I don’t have any idea how I could make the shadow edges smooth or “realistic” looking.
I was hoping that s’one will be able to shed some light on my issue.