You need the position of the light source. The current shader uses the sun position and calculates an occlusion mask, to see what is blocking the sun from the player perspectiv.
To achieve this effect you would need the position of every light source that is visible to the player, and create the occlusion mask for it. Then you could do radial filter on every vector (light - player), add the mask to the current buffer. And you should have the effect.