
The toolkit's **Animation System** includes features like retargetable animations, full control of animation weights at runtime, event calling from within the animation playback, sophisticated state machine hierarchies and transitions, blend shapes for facial animations, and much more. Please refer to the [Unity Animation](https://docs.unity3d.com/Manual/AnimationSection.html) documentation for details.

## Animation State Machines

It is common for a character or other animated Game Object to have several different animations that correspond to different actions it can perform in the game. For example, a character may breathe or sway slightly while idle, walk when commanded to and raise its arms in panic as it falls from a platform. A door may have animations for opening, closing, getting jammed, and being broken open. Mecanim uses a visual layout system similar to a flow-chart, to represent a state machine to enable you to control and sequence the animation clips that you want to use on your character or object.

Please refer to the [Unity Animation Controller](https://docs.unity3d.com/Manual/AnimatorControllers.html) documentation for details.

## Managed Runtime Support

Example **Animation State** script component:

```javascript
    module PROJECT {
        export class TestPlayerController extends BABYLON.MeshComponent {
            private animator:BABYLON.AnimationState = null;
            protected start() :void {
                this.animator = this.getComponent("BABYLON.AnimationState");
            }
            protected update() :void {
                var vertical:number = this.manager.getUserInput(BABYLON.UserInputAxis.Vertical, BABYLON.PlayerNumber.One);
                var horizontal:number = this.manager.getUserInput(BABYLON.UserInputAxis.Horizontal, BABYLON.PlayerNumber.One);
                // ..
                if (this.animator != null) {
                    this.animator.setFloat("Forward", vertical);
                    this.animator.setFloat("Strafe", horizontal);
                }
            }
        }
    }
```

## Still Under Development

The following **Animation System** features are still under development:

- 2D Blend Trees

- Animation Curves

- Animation Events

- Animation Behaviours



It is convenient to build a game object in the scene by adding components and setting their properties to the appropriate values. This can create problems, however, when you have an object like an NPC, prop or piece of scenery that is reused in the scene several times. Simply copying the object will certainly produce duplicates but they will all be independently editable. Generally, you want all instances of a particular object to have the same properties, so when you edit one object in the scene, you would prefer not to have to make the same edit repeatedly to all the copies.

Fortunately, Unity has a Prefab asset type that allows you to store a game object complete with components and properties. The prefab acts as a template from which you can create new object instances in the scene. Any edits made to a prefab asset are immediately reflected in all instances produced from it but you can also override components and settings for each instance individually.

**Note:** When you drag an asset file (eg, a Mesh) into the scene, it will create a new object instance and all such instances will change when the original asset is changed. However, although its behaviour is superficially similar, the asset is not a prefab, so you won’t be able to add components to it or make use of the other prefab features described below.

Check out the [Unity Prefab Concept Video](https://unity3d.com/learn/tutorials/topics/interface-essentials/prefabs-concept-usage) for details on the prefab usage.

## Unity Prefab System

## Using Runtime Prefabs

You can create a prefab by selecting **Asset > Create Prefab** and then dragging an object from the scene onto the “empty” prefab asset that appears. If you then drag a different game object onto the prefab you will be asked if you want to replace your current game object with the new one. Simply dragging the prefab asset from the project view to the scene view will then create instances of the prefab. Objects created as prefab instances will be shown in the hierarchy view in blue text. (Normal objects are shown in black text.)

As mentioned above changes to the prefab asset itself will be reflected in all instances but you can also modify individual instances separately. This is useful, say, when you want to create several similar NPCs but introduce variations to make them more realistic. To make it clear when a property has been overridden, it is shown in the inspector with its name label in boldface. (When a completely new component is added to a prefab instance, all of its properties will be shown in boldface.)

![Prefab Override](https://docs.unity3d.com/uploads/Main/PrefabsAddedObjectIndicator1.png)

You can also create instances of prefabs at runtime from your scripts. See the **Managed Runtime Support** section for further details.

## Editing Runtime Prefabs

The inspector for a prefab instance has three buttons not present for a normal object: **Select**, **Revert** and **Apply**.

The **Select** button selects the prefab asset from which the instance was generated. This allows you to edit the main prefab and thereby change all its instances. However, you can also save overridden values from an instance back to the originating prefab using the **Apply** button (modified transform position values are excluded for obvious reasons). This effectively lets you edit all instances (except those which override the value changed) via any single instance and is a very quick and convenient way to make global changes.

If you experiment with overriding properties but then decide you preferred the default values, you can use the **Revert** button to realign the instance with its prefab.

## Babylon Prefab Layer

![Prefab Layer](/img/exporters/unity/prefablayer.jpg)

The prefab layer can prepare your objects to take advantage of the toolkit's deep cloning to instantiate game object prefabs at runtime. This step is required to use _ **Unity Style Prefabs** _ in a web browser environment. Web games cannot directly instaniate a prefab from disk, so game objects intended to be used as runtime prefabs must be present but disabled in the scene.

By setting game objects to the **Babylon Prefab** layer you will create disabled source meshes used for deep cloning when you call the scene manager instantiate prefab function.

## Managed Runtime Support

The toolkit scene manager provides easy to use helper functions for client side prefab instantiation:

```javascript
    declare module BABYLON {
        class SceneManager {

            /** Checks the scene has the specified prefab mesh. */
            hasPrefabMesh(prefabName: string): boolean;

            /** Gets ths the raw prefab mesh from scene. */
            getPrefabMesh(prefabName: string): BABYLON.Mesh;

            /** Instantiates the specfied prefab object into scene. */
            instantiatePrefab(prefabName: string, cloneName: string, newPosition?: BABYLON.Vector3, newRotation?: BABYLON.Vector3, newScaling?: BABYLON.Vector3, newParent?: Node): BABYLON.Mesh;
        }
    }
```

Example **Runtime Prefab** script component:

```javascript
    module PROJECT {
        export class TestMeshComponent extends BABYLON.MeshComponent {
            public constructor(owner: BABYLON.AbstractMesh, scene: BABYLON.Scene, tick: boolean = true, propertyBag: any = {}) {
                super(owner, scene, tick, propertyBag);
            }
            protected start() :void {

                // Spawn player game object
                var player:BABYLON.Mesh = this.manager.instantiatePrefab("Player", "NewPlayer", BABYLON.Vector3.Zero());
                console.log("Echo Player: " + player.name);
            }
        }
    }

```



The toolkit's **Terrain Builder** system allows you to add vast landscapes to your games. At runtime, terrain rendering is highly optimized for rendering efficiency while in the editor, a selection of tools is available to make terrains easy and quick to create. Please refer to the [Unity Terrain](https://docs.unity3d.com/Manual/script-Terrain.html) documentation for details.

## Creating And Editing Terrains

To add a Terrain game object to your Scene, select **GameObject > 3D Object > Terrain** from the menu. This also adds a corresponding **Terrain Asset** to the Project view. When you do this, the landscape is initially a large, flat plane. The Terrain’s Inspector window provides a number of tools you can use to create detailed landscape features.

![Terrain Editing](https://docs.unity3d.com/uploads/Main/1.1-TerrainInspector.png)

With the exception of the tree placement tool and the settings panel, all the tools on the toolbar provide a set of “brushes” and settings for brush size and opacity. It is no coincidence that these resemble the painting tools from an image editor because detail in the terrain is created precisely that way, by “painting” detail onto the landscape. If you select the leftmost tool on the bar (Raise/Lower Terrain) and move the mouse over the terrain in the scene view, you will see a cursor resembling a spotlight on the surface. When you click the mouse, you can paint gradual changes in height onto the landscape at the mouse’s position. By selecting different options from the Brushes toolbar, you can paint with different shapes. The Brush Size and Opacity options vary the area of the brush and the strength of its effect respectively.

The details of all of the tools will be given in subsequent sections. However, all of them are based around the concept of painting detail and with the exception of the tree placement tool, all have the same options for brushes, brush size and opacity. The tools can be used to set the height of the terrain and also to add coloration, plants and other objects.

## Terrain Keyboard Shortcuts

You can use the following keyboard shortcuts in the terrain inspector:

- Press the keys from F1 to F6 to select the corresponding terrain tool (for example, F1 selects the Raise/Lower tool).

- The comma (,) and period (.) keys cycle through the available brushes.

- Shift-comma (&lt;) and Shift-dot (>) cycle through the available objects for trees, Textures and details.

Additionally, the standard F keystroke works slightly differently for terrains. Normally, it frames the selection around the whole object when the mouse is over the scene view. However, since terrains are typically very large, pressing F will focus the scene view on the area of terrain where the mouse/brush is currently hovering. This provides a very quick and intuitive way to jump to the area of terrain you want to edit. If you press F when the mouse is away from the terrain object, the standard framing behavior will return.

## Still Under Development

The following **Terrain Builder** features are still under development:

- Terrain Splatmap Shader

- Tree Billboard Meshes

- Painting Grass Meshes

- Painting Detail Prototypes

- Terrain Physics Imposters (Ammo.js)
