Lighting "refraction" and "beams" (fluid light)

I used those terms in quotations to bring attention that they are merely client side/visual aesthetics concepts that should hopefully not cause too much lag.
The idea is that a small room and a large space, when lit with congruent sources, should display different results; Obstructions should offset the emission center for the source, and negate or redirection the surrounding light levels (pic. 1). Think for example of water physics: Nearby drops change the flow direction, a fall extends the consequent stream, and in a flat surface it spreads everywhere (light and water can both be waves, heh).
A natural consequence of this 'fluid light' is beams (pic. 2) that project the emission source towards the opening, grating the same total volume of coverage while focusing itself towards the aperture.
These could either be changes to the core light engine or mere graphical effects for 'smooth lighting', which can be turned off, like an ingame vanilla-appropriate shader.