Motivation for this project was to integrate rapier2d physics into godot while keeping the scene tree editor's compositional semantics.
Unfortunately i realized too late that Godot 3.5 does not allow NativeScript's to be extended. Therefore this entire project is of little use.
Anyway it might serve as example code for bridging godot to rapier physics.
See the addons/rapier-2d-simple/examples/ folder for a working proof of concept.
I'll probably try bridging rapier2d physics again once Godot 4 and rust gdnative's GDExtensions are stable...
PS: I never got the collision signal reporting to work. Rapier supports a u128 user-data-type which i thought to abuse for raw pointers to Node2D nodes.
PPS: The codebase is really dirty and unsafe, full of RefCell's and raw pointer coercion. Rust's memory model is really disrespected here.