Small Rectangle Shape Behavior

[eldidou]

Godot version:
v3.2.1.stable.official

OS/device including version:
Ubuntu 19.04

Issue description:
When using rectangleShape with a small scale (when the RectangleShape extents multiplied by the collision shape scale is equal to 0.5 or less), if the shapes are subject to forces (like gravity) they overlap (among themselves, and with other PhysicBodies).
This is does not happen when the shape is just slightly bigger (0.6 for example), or when using another collision shape (CircleShape for example)

Steps to reproduce:

• Create several (~5) RigidBody2D
  with a RectangleShape with an extents of 0.5
  with same transform.y value
  slightly spaced on the x axis
• Reduce the default gravity to 5
• Add a StaticBody below the rigid bodies

Minimal reproduction project:
rectangleShapeOverlap.zip

[pwab]

I was able to reproduce this with your sample on my Windows 10 machine. I was able to stop the bodies from sinking by manipulating the physics_fps parameter in ProjectSettings to a value way beyond 120 (try 1000 if you want).

By the way this problem is known for quite a while:
https://www.reddit.com/r/godot/comments/7w5i47/physics_low_accuracy/

So this seems to be a duplicate of #16505 and #2092.

[Calinou]

Duplicate of #16505 and #2092.