Ouch, sounds complicated 
I was hoping to add the code from above to a custom node, plug it into material node, apply material to a low poly sphere attached to each leg of the character (and hidden in-game) O.o
It’s really just to ground characters in the scene when they are near player. It doesn’t have to be be accurate at all, nor resemble character’s shape. It should be similar to Showdown VR blob shadows, but demo doesn’t have any characters in it, except the robot and its blob shadow materials looks like a bowl of Pad Thai - I couldn’t figure out why it’s done that way and why couldn’t it be simpler
Translucency is a no-go on mobile VR. Maybe image with white background and black spot would work, using modulate blending ?