# Jolt Physics — High-Performance Rigid Body Physics Engine

> A multi-core friendly C++ physics and collision detection library used in Horizon Forbidden West and other AAA games, designed for speed and determinism.

## Install

Save as a script file and run:

# Jolt Physics — High-Performance Rigid Body Physics Engine

## Quick Use
```bash
git clone https://github.com/jrouwe/JoltPhysics.git
cd JoltPhysics/Build
cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)
# Run the samples
./build/Samples/Samples
```

## Introduction
Jolt Physics is a C++ rigid body physics library that prioritizes multi-core performance, determinism, and simulation stability. It was developed to meet the demands of AAA game production and has been battle-tested in titles like Horizon Forbidden West and Death Stranding 2.

## What Jolt Physics Does
- Simulates rigid body dynamics with continuous collision detection
- Supports convex and concave shapes, height fields, and compound colliders
- Provides constraints including hinges, sliders, cones, and ragdolls
- Parallelizes the simulation pipeline across multiple CPU cores
- Delivers deterministic results for the same input across platforms

## Architecture Overview
Jolt splits the simulation into broad-phase (spatial partitioning via a layered bounding volume hierarchy), narrow-phase (GJK/EPA for collision detection), and constraint solving (an iterative velocity solver). Work is distributed across threads using a job system with fine-grained tasks, enabling near-linear scaling on multi-core CPUs.

## Self-Hosting & Configuration
- Build with CMake on Windows, macOS, Linux, Android, iOS, and WebAssembly
- Add as a submodule or use CMake FetchContent in your project
- Configure simulation layers and collision filters via the object layer system
- Tune solver iterations, gravity, and time step in PhysicsSystem settings
- Optional debug renderer draws wireframe shapes for visual debugging

## Key Features
- Multi-core job system scales simulation across all available CPU cores
- Deterministic simulation produces identical results given identical input
- Continuous collision detection prevents fast objects from tunneling through geometry
- Soft body support for cloth and deformable object simulation
- Compact memory layout designed for cache efficiency

## Comparison with Similar Tools
- **Bullet** — Mature and widely used; Jolt is newer with better multi-core scaling
- **PhysX** — NVIDIA proprietary; Jolt is MIT-licensed and vendor-independent
- **Havok** — Commercial middleware; Jolt is free and open source
- **Box2D** — 2D only; Jolt is a full 3D rigid body engine
- **Rapier** — Rust-based physics; Jolt targets C++ with proven AAA production use

## FAQ
**Q: Is Jolt Physics production-ready?**
A: Yes. It ships in AAA games including Horizon Forbidden West and Death Stranding 2 by Guerrilla Games and Kojima Productions.

**Q: Does Jolt support soft bodies?**
A: Yes. Jolt includes soft body simulation for cloth, pressure-based volumes, and deformable meshes.

**Q: Can I use Jolt with engines other than custom ones?**
A: Community integrations exist for Godot, Bevy, and other engines. The library is engine-agnostic and designed for easy embedding.

**Q: How does determinism work across platforms?**
A: Jolt avoids platform-dependent floating point behavior and guarantees bitwise identical results when given the same input and configuration, regardless of operating system.

## Sources
- https://github.com/jrouwe/JoltPhysics
- https://jrouwe.github.io/JoltPhysics/


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Source: https://tokrepo.com/en/workflows/asset-7b9ec73b
Author: Script Depot