I'm using the Houdini 13 Sky Rig to render clouds, and they look great!
However, The camera is traveling under rain clouds, and I wand the clouds to transition to less dense clouds.
The less dense clouds will be created by hand using the cloud and cloud rig type objects.
I want to feather the sky rig box volume into the hand placed less dense cloud rig objects.
Can someone show me how to add a density ramp to the sky rig SOP/shotnet/sky VEX network? It would be based on bounding box coordinates.

The reason I want to do it at the shader level is the sky rig shader is much faster than geometry-based cloud rendering.

For the expanse of sky I need, using actual VDB volumes are too expensive.

Any suggestions would be much appreciated.

Thanks

Jeroen

I should clarify: the sky rig uses a bounding box, and the procedural clouds are clipped at the box boundaries. I need an efficient/shader level way to have the clouds taper off in density towards the boundaries.