How to add 3D shadows on a 2D sprite that looks directly into the camera?

Question

So I have a 3D sprite with a 2D character like this

My intend is to add 3D Shadows on the character but a problem occurred. Because I enable the y-billboard mode on my 3D sprite, which means the sprite will always look at the camera, so whenever I changed my camera angles the shadow's direction just gets completely messed up.

As you can see, the shadow also overlaps the player.

I once had a debate about this issue with my very friend, and soon we realized that the solution is pretty much complex. I had run out of ideas and would really appreciate it if anyone could help me to approach the problem, or at least give me some hint about what I might misunderstanding.

(my Godot engine version is 3.05.1 btw, and also sorry for my bad English.)

Answer 1

fixed it, just create another sprite and set it as shadow-only