Hide objects but render shadows they would throw?

Hi,

I am trying to find an easy way to create an effect for a theater-show where the shadow of an actor changes without changing the physical light situation but “projecting rendered shadow”.

So in TouchDesigner I used a simple 3d body obj together with a moving light, which gives me a moving shadow.

Now I’m looking for a solution to only render the shadow, hiding the body obj.
Any ideas how to solve that?

Best, Robert

OK, partially found the solution, maybe it’s useful for s.o. else as well:

In der Render TOP, replace geometry:* to the geometry objects that the shadows will be thrown onto, leaving out the shadow producing geometries.

Now, of course also the computed light situation changes. But I want to create this surreal effect that shadow changes without the lights changing.
How would I now separate the shadow from the background and put it into a constant light environment?