
# Support for Physics Engines

Physics engines are third party external programs that can be plugged into Babylon.js. They, depending on their features, emulate "real-life" interactions between objects, which can be meshes, solid particles from the solid particle system or some cameras. One feature of a Physics Engine is the addition of gravity to a scene.

There are 2 physics architecture in Babylon.js.

- a Version 2 (V2 for short) with support for modern Physics Engines.

  > [🚀 You can find the V2 API documented here.](/features/featuresDeepDive/physics/usingPhysicsEngine)  

- Version 1 (V1 for short), which is a pre-6.0 Legacy API.

  > [⚠️ The documentation for V1 has been moved to the Legacy section.](/legacy/physics)

#### We strongly recommend using V2 over V1. [A migration guide is here](/features/featuresDeepDive/physics/migrate).

## Physics V2

There are plugins for 1 physics engine:

1. Havok - a powerful engine used in AAA games.

All need to be enabled before use.

This architecture allows finer grain control on your physics scene by making the difference between collision shapes and physical body.
A typical use case is to have only one collision shape used by numerous bodies.
This allows a lower memory footprint and more efficient memory addressing.
A special effort has been put into better performance for a huge number of bodies. This is also the case for the collision callback mechanism.

A broad overview of the Physics V2 advancements is available on this [Medium article](https://medium.com/@babylonjs/physics-v2-overview-ed36039ce1e7).

## Physics V1

There are plugins for 3 physics engines:

1. Cannon.js - a wonderful physics engine written entirely in JavaScript.
2. Oimo.js - a JS port of the lightweight Oimo physics engine.
3. Ammo.js - a JS port of the bullet physics engine.

All need to be enabled before use.

Interactions between objects are achieved by imposters, simple objects that are attached to any complex objects with a scene. The imposter can be assigned physical attributes such as mass, friction, a coefficient of restitution, impulse, and linear and angular.

Two imposters can be connected using joints such as a hinge or ball and socket.

Ammo also allows the creation of soft bodies.



## Legacy Features

Keeping back-compatibility is one of the main tenets of Babylon.js. However, with changes in technology, we sometimes have to make the decision to move older features to "Legacy" status, so that we can develop more modern and efficient approaches to problems. When a legacy feature has a more modern approach, it is advised to move to the modern approach when possible. This section lists all of our legacy features.



Good performance is critical to the success of many games. The graphical parts of your game can primarily impact on two systems of the computer: the GPU and the CPU.

**Common Bottlenecks:**

- The **GPU** has too many vertices to process. The number of vertices that is acceptable to ensure good performance depends on the GPU and the complexity of vertex shaders. Generally speaking, aim for no more than 100,000 vertices on mobile. A PC manages well even with several million vertices, but it is still good practice to keep this number as low as possible through optimization.

- The **CPU** has too many vertices to process. This could be in skinned meshes, cloth simulation, particles, or other game objects and meshes. As above, it is generally good practice to keep this number as low as possible without compromising game quality. See the section on CPU optimization below for guidance on how to do this.
  If rendering is not a problem on the GPU or the CPU, there may be an issue elsewhere - for example, in your script or physics. Use the Unity Profiler to locate the problem.

The art tools provided by the toolkit allow you to optimize your game assets for maximum performance using the **WebGL** platform.

# Maya Arts Tools

**Maya Scripts** plattform folder locations:

- **Windows** - C:\Users\USERNAME\Documents\maya\*VERSION\*\scripts

- **Macintosh** - ~/Library/Preferences/Autodesk/maya/_VERSION_/scripts

Check out the [Maya Arts Tools Tutorial](http://www.babylontoolkit.com/videos/MayaArtTools.mp4) to get started optimizing your geometry for web based game development.

# Babylon Reskin Tool

Reskin and combine selected meshes with new max influencers. Download and install the [Babylon Reskin Tool](https://github.com/BabylonJS/Exporters/blob/master/Maya/Tools/babylonReskinTool.mel) file in your **Maya Scripts** folder.

Open the Script Editor and go to the Mel tab, copy and paste command below:

    babylonReskinTool();

Highlight it and click on "Save Script to Shelf...", specify a name ('Reskin') and click "OK".

# Babylon Namespace Tool

Removes unwanted namespace text from selected object. Download and install the [Babylon Namespace Tool](https://github.com/BabylonJS/Exporters/blob/master/Maya/Tools/babylonReskinTool.mel) file in your **Maya Scripts** folder.

Open the Script Editor and go to the Mel tab, copy and paste command below:

    babylonNameTool();

Highlight it and click on "Save Script to Shelf...", specify a name ('Names') and click "OK".

# Unity Art Tools

# Geometry Tools

The geometry tools help improve overall scene performance by optimizing game art for **WebGL** rendering. The toolkit supports combining meshes, seperating meshes, generating blocking volumes for collision and baking a texture atlas for **Static Mesh Filter** game objects.

![Geometry Tools](/img/exporters/unity/combinemeshes.jpg)

# Height Mapping

The height mapping tool enables **16-Bit RAW Greyscale** image manipulations. This is very useful to convert to and from **RAW** and **PNG** image formats and to scale height maps to the desired mesh detail resolution.

![Height Mapping](/img/exporters/unity/heightmapping.jpg)

# Cubemap Baking

The cubemap baking tool can pre bake environment **Skybox** and **Radiance** texture images. The toolkit supports **Low Dynamic Range**, **High Dynamic Range**, and **Direct Draw Surface** image file formats. An internal [Cubemap Filtering Tool](https://github.com/dariomanesku/cmft) plugin is used to process cubemap textures. It reaches very fast processing speeds by utilizing both multi-core CPU and OpenCL GPU at the same time.

![Cubemap Baking](/img/exporters/unity/cubemapbaking.jpg)

# Texture Atlas Skin

The texture atlas skin tool allows you to bake a texture atlas for **Skinned Mesh Renderer** game objects. It will parse all the sub meshes (materials) and combine all the textures into a group of texture atlas images. The toolkit will encode new uv sets and bake new geometry assets using the combined texture atlas material assets.

![Texture Atlas Skin](/img/exporters/unity/textureatlasskin.jpg)


Legacy

Legacy Features

Coming next

Physics

Learn all about the powerful physics capabilities of Babylon.js.