## Introduction
The Editor allows to setup and edit physics impostors for meshes in the scene using the inspector. All physics engines are supported:
* `CannonJS`
* `OimoJS`
* `AmmoJS`

By default, physics is enabled in the project and is using `CannonJS`.

## Setting up physics
By selecting a mesh or mesh instance (basically any object extending `AbstractMesh`) in the scene, the inspector will be updated to show the object's properties. For meshes and meshes instances, some properties are focusing on physics located in the folder named `Physics`. By default, all unconfigured meshes have no impostor (`NoImpostor`).

At the moment, the available impostors are:
* `BoxImpostor`
* `SphereImpostor`
* `CylinderImpostor`

By selecting a new impostor, the tool will be updated to show the common properties which are:
* `Mass`
* `Restitution`
* `Friction`

A documentation for all these options is [available here](/features/featuresDeepDive/physics/usingPhysicsEngine#options).

Once these properties are configured, the physics is not preview-able in the Editor. To preview the result, just run the project to see the physics effect and adjust the properties if needed by clicking on the button `Play` in the tools toolbar.

In the following example, the box and ground already have an impostor set to `BoxImpostor` where the box has a mass of 1 and the ground has a mass of 0 (to stay static).

![SettingPhysics](/img/extensions/Editor/UsingPhysics/setting_physics.gif)

## Changing gravity
When selecting the scene in the scene graph, there are 2 editable gravity properties:
* Collisions gravity
* Physics gravity

According to the wanted effect, both gravity values can be distinct. In the `Physics` folder of the scene inspector the gravity applied by the physics engine can be customized:

![SettingGravity](/img/extensions/Editor/UsingPhysics/setting_gravity.gif)

## Choosing physics engine
Using the inspector, the scene's properties allow to change the physics engine that should be used by the project. By default, `CannonJS` is used and can be replaced by OimoJS and AmmoJS. Changing the physics engine can be done without having to reset or redefine the impostors already existing.

![SettingEngine](/img/extensions/Editor/UsingPhysics/setting_engine.gif)

Once desired physics engine is selected, the project must be updated as well. In fact, by default the project templates are using `CannonJS` where the library is imported in the `index.html` file. In case of using `OimoJS` for example, this import must be replaced by the one that imports `OimoJS`. The default template looks like:

```html
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">

    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>Babylon.js Generated Template</title>

        
        <script src="./dist/bundle.js" type="text/javascript"></script>

        
        <script src="./node_modules/cannon/build/cannon.js" type="text/javascript"></script>

        ...
    </head>

    <body>
        ...
    </body>

</html>
```

In other words, for this example, the `CannonJS` import should be replaced to load the file `Oimo.js` from CDN or any other corresponding file in `node_modules`:

```html
<script src="https://cdn.babylonjs.com/Oimo.js" type="text/javascript"></script>
```

Or using `AmmoJS`:

```html
<script src="https://cdn.babylonjs.com/ammo.js" type="text/javascript"></script>
```

Which gives, for example with `AmmoJS`:

```html
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">

    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>Babylon.js Generated Template</title>

        
        <script src="./dist/bundle.js" type="text/javascript"></script>

        
        <script src="https://cdn.babylonjs.com/ammo.js" type="text/javascript"></script>

        ...
    </head>

    <body>
        ...
    </body>

</html>
```


Descriptions of how to create, edit and attach scripts on nodes in scene using the Babylon.js Editor.



## Introduction

The Editor api provides some tools, as decorators, to help listening events globally and on nodes. In other words, for
example on pointer events, the api can listen for events and pick the selected mesh in order to notify the decorated
method(s).

For example, listening for pointer event `pointer tap` on the current mesh having this script attached:

```typescript
import { Mesh } from "@babylonjs/core/Meshes/mesh";
import { Vector3 } from "@babylonjs/core/Maths/math.vector";
import { PointerEventTypes, PointerInfo } from "@babylonjs/core/Events/pointerEvents";

import { onPointerEvent } from "../decorators";

export default class MyMeshComponent extends Mesh {
    private _physicsEnabled: boolean = true;

    ...

    @onPointerEvent(PointerEventTypes.POINTERTAP, true)
    protected _tapped(info: PointerInfo): void {
        if (!this._physicsEnabled) {
            return;
        }

        const force = this.getDirection(new Vector3(0, 0, 1));
        this.applyImpulse(force, this.getAbsolutePosition());
    }

    ...
}
```

## Available Decorators

### On Pointer Event

To listen pointer events, the decorator `@onPointerEvent` can be used to decorate methods to call.
This decorator takes 2 arguments:
- the pointer event type (`PointerEventTypes` from `@babylonjs/core/Events/pointerEvents`).
- a boolean to indicate whether or not the method should be called only when, in case of a mesh, the mesh is picked.

The second boolean parameter is set to `true` by default. That means it must be set to `false` in order to listen
the pointer event globally.

```typescript
@onPointerEvent(PointerEventTypes.POINTERTAP, false)
protected _tapped(info: PointerInfo): void {
    // Called on the user clicks anywhere on the canvas.
}

@onPointerEvent(PointerEventTypes.POINTERTAP, true)
protected _tapped(info: PointerInfo): void {
    // Called on the user clicks on the mesh.
}
```

The method signature can define the `PointerInfo` reference which contains all the pointer event info such as we get
using `scene.onPointerObservable.add((info) => { ... })`.

**Note: the method will be called only and only if the scene containing the mesh is instantiated in the game/application**

### On Keyboard Event

As for `@onPointerEvent` decorator, the `@onKeyboardEvent` decorator can be used to decorate methods in a script.
This decorator takes 2 arguments:
- the key of keys to listen (as numbers or strings).
- the type of keyboard event to listen (key up or key down).

**Note: keyboard events are always listened globally**

Example listening for the `z` key being up:

```typescript
@onKeyboardEvent("z", KeyboardEventTypes.KEYUP)
protected _keyup(info: KeyboardInfo): void {
    console.log(info.event.key);
}
```

Multiple keys can be listened at the same time where the decorated method will be called when any of the specified
keys is triggered:

```typescript
@onKeyboardEvent(["z", "q", "s", "d"], KeyboardEventTypes.KEYUP)
protected _keyup(info: KeyboardInfo): void {
    console.log(info.event.key);
}
```

Using key codes instead of key values is deprecated but is still supported.

```typescript
@onKeyboardEvent(32 /* or [32, 53] for multiple keys */, KeyboardEventTypes.KEYUP)
protected _keyup(info: KeyboardInfo): void {
    console.log(info.event.keyCode);
}
```


Attaching scripts in Babylon.JS Editor

Coming next

Using Physics

Understanding how to create and edit physics in a Babylon.JS Editor project