nilpunch / unity-prediction-rollback

Deterministic prediction-rollback netcode library for Unity.

unity-prediction-rollback

Important

There is a much simpler and more reliable solution for prediction-rollback - Masssive ECS

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It was an interesting experiment, but there are many problems with it. So, DO NOT USE IN PRODUCTION!.

Deterministic prediction-rollback netcode library for fast-paced games.
Library does not reference Unity Engine, so it could be used in a regular C# project.
P.S. currently, only samples references Unity Engine.

Goals

1. Responsive controls with no delay
2. Unlimited session length with late-joins
3. Easy client-side coding with Unity (no ECS)
4. Clean and simple OOP architecture
5. Cross-platform determinism

Overview

This is a library, not a framework. Thus, the user controls everything that happens.

Implemented features:

1. Prediction-rollback with zero GC allocations
2. Live command timeline - make changes in the past and see immediate effect upon the future
3. Distributed simulation - killer feature, allowing for many great things
4. Algorithmic command prediction
   • Input replication
   • Input decay (fading out)
5. Snapshots memory recycling on demand
6. Replays with command history

TODO:

1. Commands serialization
2. State serialization for late-joins
3. Actual networking

Recent progress

Here is some simple shooter with prediction-rollback features.

Input prediction sample. When there is no input from the player, the movement is fading out, and the shooting repeates in the last direction.

movie_017.mp4

Live simulation replay sample.

movie_013.mp4