Baking shadows with Alpha

Corona Corona for 3ds Max Help Required
1

Hi Everyone
Wondering if there is a way to do this

We are trying to bake a shows plane with the shadow of furniture when we bake map furniture
The shadow would be baked into a texture with alpha channel.
Is this possible to do in Corona using render to texture?
is there another method to capture corona soft shadows with alpha channel for use in a game engine?
Thanks ahead of time
Mike K

2

I bake AO pass, then invert it and use as opacity mask. If you want more refined shadow, then you assign white material to the floor, bake its beauty pass, desaturate, invert, adjust levels in photoshop and use it as alpha.