godot-jolt

Godot Jolt is a native extension for the Godot game engine that allows you to use the Jolt physics engine to power Godot's 3D physics.

It functions as a drop-in replacement for Godot Physics, by implementing the same nodes that you would use normally, like RigidBody3D or CharacterBody3D.

Important

As of Godot 4.4, this integration of Jolt Physics is built into Godot itself, in the form of an engine module. As such, this extension will be considered to be in maintenance mode going forward, where only bug fixes will be considered for merging.

At the time of writing, the Godot engine module does not have full feature parity with this extension, and is lacking things like the joint interface changes (JoltHingeJoint3D, etc.) that this extension exposes. However, once the engine module does reach feature parity in some way, and a new stable release of Godot is out with said feature parity, this extension will be considered fully deprecated and this repository will likely be archived entirely.

Table of Contents

• What features are there?
• What about determinism?
• What's not supported?
• What else is different?
• What versions of Godot are supported?
• What platforms are supported?
• How do I get started?
• What settings are there?
• How do I build from source?
• What's the license?

What features are there?

Better performance, mainly, but also generally having a more stable simulation compared to Godot Physics.

There are also (completely optional) substitute nodes available for all the joints, which line up better with the interface that Jolt offers than what the default joints do. This allows for things like breakable joints, soft limits and the ability to override solver iterations per-joint.

What about determinism?

While Jolt itself offers deterministic simulations, Godot Jolt is not able to make such guarantees. Simulations in Godot Jolt may look deterministic, and may even happen to be deterministic, but this should not be relied upon if determinism is a hard requirement.

What's not supported?

• The physics server is not thread-safe
• Memory usage is not reflected in Godot's performance monitors
• SoftBody3D does not support any interactions with Area3D

What else is different?

• Scale is actually used for all bodies, shapes and shape queries, except for SoftBody3D
• Joints only support soft limits through their substitutes (JoltHingeJoint3D, etc.)
• Springs and linear motors are actually implemented in Generic6DOFJoint3D
• Single-body joints will make node_a be the "world node" rather than node_b
• Ray-casts returning face_index is opt-in, at a potentially heavy memory cost
• Shape-casts should be more accurate, but their cost also scale with the cast distance
• Shape margins are used, but are treated as an upper bound and scale with the shape's extents
• Manipulating a body's shape(s) after it has entered a scene tree can be costly
• Contact impulses are estimations and won't be accurate when colliding with multiple bodies
• Contact reporting for kinematic bodies is partially opt-in, at a potentially heavy performance/memory cost
• ConvexPolygonShape3D uses a more accurate center-of-mass and inertia

Also consider this note from Jolt's documentation:

In order for the simulation to be accurate, dynamic objects should be in the order of 0.1 to 10 m long, have speeds in the order of 0 to 500 m/s and have gravity in the order of 0 to 10 m/s^2. Static object should be in the order of 0.1 to 2000 m long.

What versions of Godot are supported?

Currently the only supported versions of Godot are between 4.3 and 4.6.

What platforms are supported?

• Windows (x86-64, x86)
• Linux (x86-64, x86)
• macOS (x86-64 + Apple Silicon)
• iOS
• Android (ARM64, ARM32, x86-64, x86)

Note that Linux support is limited to glibc 2.35 or newer, which for Ubuntu means 22.04 (Jammy Jellyfish) or newer.

How do I get started?

1. Download it here
2. Extract the files to your project directory
3. Start (or restart) Godot
4. Open your project settings
5. Make sure "Advanced Settings" is enabled
6. Go to "Physics" and then "3D"
7. Change "Physics Engine" to "Jolt Physics (Extension)"
8. Restart Godot

What settings are there?

See docs/settings.md for information about the project settings available in Godot Jolt.

How do I build from source?

See docs/building.md for information about how to build Godot Jolt from source.

What's the license?

Godot Jolt is distributed under the MIT license. See LICENSE.txt for more details and THIRDPARTY.txt for third-party licenses.