https://github.com/Kimbatt/unity-deterministic-physics

Cross-platform deterministic physics simulation in Unity, using DOTS physics and soft floats
https://github.com/Kimbatt/unity-deterministic-physics

deterministic physics physics-engine physics-simulation unity unity3d

Last synced: 3 months ago
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Cross-platform deterministic physics simulation in Unity, using DOTS physics and soft floats

• Host: GitHub
• URL: https://github.com/Kimbatt/unity-deterministic-physics
• Owner: Kimbatt
• Created: 2021-02-16T17:56:07.000Z (almost 4 years ago)
• Default Branch: master
• Last Pushed: 2024-02-14T00:32:54.000Z (12 months ago)
• Last Synced: 2024-08-02T05:13:12.619Z (6 months ago)
• Topics: deterministic, physics, physics-engine, physics-simulation, unity, unity3d
• Language: C#
• Homepage:
• Size: 12.5 MB
• Stars: 470
• Watchers: 12
• Forks: 60
• Open Issues: 13
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-unity3d - unity-deterministic-physics - Cross-platform deterministic physics simulation in Unity, using DOTS physics and soft floats (Open Source Repositories / DOTS)

README

        
# Unity deterministic physics

This is a modified version of [Unity DOTS Physics version 0.6.0-preview.3](https://docs.unity3d.com/Packages/[email protected]/manual/index.html), which supports cross-platform deterministic physics simulation by using [soft floats](https://github.com/Kimbatt/soft-float-starter-pack).

## Usage

The following packages must be installed:

- Burst

- Collections

- Entities

- Jobs

You'll need to use the `UnityS.Physics` and the `UnityS.Mathematics` namespaces instead of the usual `Unity.Physics` and `Unity.Mathematics`.

See [Unity Physics manual](https://docs.unity3d.com/Packages/[email protected]/manual/index.html) for documentation.

## Notes on determinism

For a deterministic physics simulation:

- All bodies must be created in the same order every time you create the simulation

- Bodies must only be modified in a system that is updated in FixedStepSimulationSystemGroup

- You must not use the result of floating point operations as input for the physics engine

- Be careful when using hashmaps / hashsets, because iterating over them may be non-deterministic (it depends on the implementation).

- Check how to use soft floats [here](https://github.com/Kimbatt/soft-float-starter-pack#how-to-use).

- Make sure that your code is also deterministic.

## Example

See the ExampleScene scene for an example. After running it, your simulation should look exactly like this:

![](deterministic.gif)

## License

`Unity.Physics`, `Unity.Mathematics`, and `Unity.Transforms` are licensed under the [Unity Companion License](https://unity3d.com/legal/licenses/Unity_Companion_License).

`Soft floats` is licensed under the MIT License. See [https://github.com/Kimbatt/soft-float-starter-pack](https://github.com/Kimbatt/soft-float-starter-pack) for more information.