Shadow Pass With Fluids?

[timothyfolk]

Hi

I have a thick plume of smoke that casts a shadow onto the ground. As i'm integrating the smoke into a moving shot, i need the ground to be a use background shader to catch the shadow cast by the thick fluid to composite with. However the use background shader isnt picking up the shadow cast from the fluid.

What do I do here? I need that shadow to composite with, but the usual way I do this for other non-fluid projects is to use that background shader to get the shadow pass.

image from a frame of the shot:

Many thanks

[gmask]

try setting a new scene with basic objects to test the workflow for setting it up

[timothyfolk]

Yeah I did that, and thats how i found out fluid shadows cant be caught on a use background shader, whereas other solid objects can. Cheers though.

Any other ideas?