GDNative Ropesim

A 2D verlet integration based rope simulation for Godot 4.2.

The computation-heavy simulation part is written in C++ using GDExtension, the rest in GDScript. This allows for fast processing and easy extendability, while keeping the code readable.

The last Godot 3.x version can be found on the 3.x branch, however, this branch will no longer receive updates.

Setup

1. Get the addon
   • Download from the asset store, or
   • Download the latest release from the release page, or
   • Download it from the latest GitHub Actions run, or
   • Compile it yourself.
2. Copy or symlink addons/ropesim to your project's addons/ directory
3. Enable the addon in the project settings
4. Restart Godot

Building

First, clone or download the repository and run git submodule update --init --recursive.

See here on how to create and compile GDExtension libraries.

To compile for Linux, run the following commands. Compiling for other platforms works analogously.

$ scons target=template_release platform=linux arch=x86_64 -j8
$ scons target=template_debug platform=linux arch=x86_64 -j8

Output files are saved to demo/addons/ropesim/bin/.

Documentation

Following nodes exist:

• Rope: The basic rope node. Optionally renders the rope using draw_polyline().
• RopeAnchor: Always snaps to the specified position on the target rope. Optionally, also adapts to the rope's curvature. Can be used to attach objects to a rope.
• RopeHandle: A handle that can be used to control, animate, or fixate parts of the rope.
• RopeRendererLine2D: Renders a target rope using Line2D.
• RopeCollisionShapeGenerator: Can be used e.g. in an Area2D to detect collisions with the target rope.

See inline comments for further information and documentation of node properties.

The included demo project and the showcase video below provide some usage examples.

When one of these nodes is selected, a "Ropesim" menu appears in the editor toolbar that can be used to toggle live preview in the editor on and off.

All rope related tools, automatically pause themselves when their target rope is paused to save performance.

Showcase

A quick overview of how to use each node.

https://user-images.githubusercontent.com/7116001/216790870-4e57fce0-7981-44f5-9963-daa1d9751abf.mp4

Jellyfish with rope simulated tentacles.

https://user-images.githubusercontent.com/7116001/216791913-35321ddb-ee35-44e2-85ba-0632a1123fda.mp4