Parti-volume shader

[Dave Buckley]

Trying to get a volumetric effect coming through some gaps in a wall from an external sun source - (daylight system - mrsun mrsky), however i seem to be getting the effect across the entire scene rather than just on the beams coming through the gaps, does any one know how to limit the effect just to the light coming directly through the gaps. I am guessing that i have the effect across the entire scene, as it is a volume shader and that the light source it is linked to is bouncing light around the entire scene.

 

Ok i'l shorten it, i want the effect on the direct illumination of the daylight system only, i need to exclude the indirect illumination from the effect, a render will follow when it is finished . . .zzz . . .zzz . . .zzz