# Multithreading Bullet Physics in jme3

## Introduction

Since bullet is not (yet) multithreaded or GPU accelerated the jME3 implementation allows to run each physics space on a separate thread that is executed in parallel to rendering.

## How is it handled in jme3 and bullet?

A SimpleApplication with a BulletAppState allows setting the threading type via

    setThreadingType(ThreadingType type);

where ThreadingType can be either SEQUENTIAL or PARALLEL.

In the simpleInitApp() method:

    bulletAppState = new BulletAppState();
    bulletAppState.setThreadingType(BulletAppState.ThreadingType.PARALLEL);
    stateManager.attach(bulletAppState);

The physics update happens in parallel to rendering, after the users changes have been made in the update() call. This way the loop logic is still maintained: the user can set and change values in physics and scenegraph objects before render() and physicsUpdate() are called in parallel.

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