How to add additional collision shape to RigidBody2D that not interacts in physics and just reports about collisions?

Question

I need additional collision shape that doen't take a part in physics but reports about collisions of bullets with it. Bullets should not to collide to other player collision shapes (except colliding with that collision shape) but when it stops to collide with that shape it should became regular object that collides with other player collision shapes (and doesn't collide with that shape anymore).
And bullets should to collide with enemies collision shapes even if it still collides that special collision shape of player (if we talk about enemies, the enemy will be player and player will be enemy. I can put weapon to any object)

How to correctly implement this in Godot 3.2?

Answer 1

I believe you're looking for Area node:
https://docs.godotengine.org/en/stable/tutorials/physics/using_area_2d.html

https://docs.godotengine.org/en/stable/classes/class_area.html

Area monitors for collisions, but objects go through it instead of colliding.

Answer 2

Check out this question. There is a good explanation about layers and mask, it is a good tool what sure can solve your problem, it is matter of administration. You can use a layer for you player and a different one for your extra collision, that way they can do specific actions and don't interrupt each other. I hope this solves your problem.