Changing radius of RigidBody2D's shape ignores Area2D gravity

[bram-dingelstad]

Godot version:
v3.2.beta1.official

OS/device including version:
Ubuntu 18.04.3 LTS

Issue description:
When changing the radius of a RigidBody2D's CircleShape2D, an Area2D's gravity is ignored.

(Apologies for low frame rate recording)

The yellow circle is the Area2D in the minimal reproduction project, the red circle is the RigidBody2D. Issue might be related to #33369 and #19271 as I also ran into those while running into this issue.

Also doesn't work when trying to use with non-gravity point Area2D.
Also doesn't work when using non CircleShape2D shapes for the Area2D.

Steps to reproduce:

1. Create a RigidBody2D node with a CircleShape2D for a shape that dynamically grows
2. Create an Area2D node with Gravity Point enabled and Space Override set to Replace
3. Let RigidBody2D grow inside of Area2D to observe effect

Minimal reproduction project:
minimal-reproduction-project.zip

[bram-dingelstad]

Let me know if there's anything I can do to help!

[tom-jk]

Testing on linux mint 18.3.
Can reproduce in 3.2.beta1, 3.2.3.rc3.

If you connect the Area2D's body_entered and body_exited signals to functions that print "entered"/"exited", you'll see that a resize causes the player to exit, and resizes on successive frames keep it from re-entry.

First, you should really only interact with physics in a _physics_process function, not a _process function (but that doesn't make a practical difference here).

If you replace

$CollisionShape2D.shape.radius = size

with

$CollisionShape2D.shape.set_deferred("radius", size)

the problem is resolved.