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Class MotionPath

Package | com.greensock.motionPaths
Class | public class MotionPath
Inheritance | MotionPath flash.display.Shape
Subclasses | CirclePath2D, LinePath2D, RectanglePath2D

A MotionPath defines a path along which a PathFollower can travel, making it relatively simple to do things like tween an object in a circular path. A PathFollower's position along the path is described using its `progress` property, a value between 0 and 1 where 0 is at the beginning of the path, 0.5 is in the middle, and 1 is at the very end of the path. So to tween a PathFollower along the path, you can simply tween its `progress` property. To tween ALL of the followers on the path at once, you can tween the MotionPath's `progress` property. PathFollowers automatically wrap so that if the `progress` value exceeds 1 or drops below 0, it shows up on the other end of the path.
Since MotionPath extends the Shape class, you can add an instance to the display list to see a line representation of the path drawn which can be helpful especially during the production phase. Use `lineStyle()` to adjust the color, thickness, and other attributes of the line that is drawn (or set the MotionPath's `visible` property to false or don't add it to the display list if you don't want to see the line at all). You can also adjust all of its properties like `scaleX, scaleY, rotation, width, height, x,` and `y` just like any DisplayObject. That means you can tween those values as well to achieve very dynamic, complex effects with ease.

Example
Example AS3 code:

    import com.greensock.*;
    import com.greensock.plugins.*;
    import com.greensock.motionPaths.*;
    TweenPlugin.activate([CirclePath2DPlugin]); //only needed once in your swf, and only if you plan to use the circlePath2D tweening feature for convenience

    //create a circle motion path at coordinates x:150, y:150 with a radius of 100
    var circle:CirclePath2D = new CirclePath2D(150, 150, 100);

    //tween mc along the path from the bottom (90 degrees) to 315 degrees in the counter-clockwise direction and make an extra revolution
    TweenLite.to(mc, 3, {circlePath2D:{path:circle, startAngle:90, endAngle:315, autoRotate:true, direction:Direction.COUNTER_CLOCKWISE, extraRevolutions:1}});

    //tween the circle's rotation, scaleX, scaleY, x, and y properties:
    TweenLite.to(circle, 3, {rotation:180, scaleX:0.5, scaleY:2, x:250, y:200});

    //show the path visually by adding it to the display list (optional)
    this.addChild(circle);

    //--- Instead of using the plugin, you could manually manage followers and tween their "progress" property...

    //make the MovieClip "mc2" follow the circle and start at a position of 90 degrees (this returns a PathFollower instance)
    var follower:PathFollower = circle.addFollower(mc2, circle.angleToProgress(90));

    //tween the follower clockwise along the path to 315 degrees
    TweenLite.to(follower, 2, {progress:circle.followerTween(follower, 315, Direction.CLOCKWISE)});

    //tween the follower counter-clockwise to 200 degrees and add an extra revolution
    TweenLite.to(follower, 2, {progress:circle.followerTween(follower, 200, Direction.COUNTER_CLOCKWISE, 1)});

NOTES

- All followers are automatically updated when you alter the MotionPath that they're following.
- To tween all followers along the path at once, simply tween the MotionPath's `progress` property which will provide better performance than tweening each follower independently.

Copyright 2011, GreenSock. All rights reserved. This work is subject to the terms in http://www.greensock.com/terms_of_use.html or for corporate Club GreenSock members, the software agreement that was issued with the corporate membership.

Public Properties

| Property | Defined by
--- | --- | ---
|  | followers : Array [read-only] Returns an array of all PathFollower instances associated with this path | MotionPath
|  | height : Number | MotionPath
|  | progress : Number A value between 0 and 1 that can be used to move all followers along the path. | MotionPath
|  | rawProgress : Number Identical to `progress` except that the value is not re-interpolated between 0 and 1. | MotionPath
|  | rotation : Number | MotionPath
|  | scaleX : Number | MotionPath
|  | scaleY : Number | MotionPath
|  | targets : Array [read-only] Returns an array of all target instances associated with the PathFollowers of this path | MotionPath
|  | visible : Boolean | MotionPath
|  | width : Number | MotionPath
|  | x : Number | MotionPath
|  | y : Number | MotionPath

Public Methods

| Method | Defined by
--- | --- | ---
|  | addFollower(target:*, progress:Number = 0, autoRotate:Boolean = false, rotationOffset:Number = 0):PathFollower Adds a follower to the path, optionally setting it to a particular progress position. | MotionPath
|  | distribute(targets:Array = null, min:Number = 0, max:Number = 1, autoRotate:Boolean = false, rotationOffset:Number = 0):void Distributes objects evenly along the MotionPath. | MotionPath
|  | getFollower(target:Object):PathFollower Returns the PathFollower instance associated with a particular target or null if none exists. | MotionPath
|  | lineStyle(thickness:Number = 1, color:uint = 0x666666, alpha:Number = 1, pixelHinting:Boolean = false, scaleMode:String = "none", caps:String = null, joints:String = null, miterLimit:Number = 3, skipRedraw:Boolean = false):void Sets the line style for the path which you will only see if you add the path to the display list with something like addChild() and make sure the visible property is true. | MotionPath
|  | removeAllFollowers():void Removes all followers. | MotionPath
|  | removeFollower(target:*):void Removes the target as a follower. | MotionPath
|  | renderObjectAt(target:Object, progress:Number, autoRotate:Boolean = false, rotationOffset:Number = 0):void Positions any object with x and y properties on the path at a specific progress position. | MotionPath
|  | update(event:Event = null):void Forces the MotionPath to re-render itself and all of its followers. | MotionPath

Property detail

followers | property

`followers:Array` [read-only]

Returns an array of all PathFollower instances associated with this path

Implementation
`public function get followers():Array`

height | property |

`height:Number` [read-write]

Implementation
`public function get height():Number`
`public function set height(value:Number):void`

progress | property |

`progress:Number` [read-write]

A value between 0 and 1 that can be used to move all followers along the path. `progress` is identical to `rawProgress` except that the `rawProgress` is not re-interpolated between 0 and 1. For example, if you set the motion path's `rawProgress` to 2.1, `progress` would be 0.1 (the corresponding value between 0 and 1), essentially wrapping it. If `rawProgress` is set to -3.4, `progress` would be 0.6. You may set `progress` to any value but it will be re-interpolated to its corresponding value between 0 and 1 very much like a DisplayObject's "rotation" property in Flash where setting it to 270 works fine but when you trace() the rotation value it will report as -90 instead. Setting `progress` affects `rawProgress` too. For example:
`myPath.progress = 2.1;
trace(myPath.progress); //traces "0.1"
trace(myPath.rawProgress); //traces "2.1"
` Either property can be used to move all followers along the path. Unlike a PathFollower's `progress` or `rawProgress`, this value is not absolute for motion paths - it simply facilitates relative movement of followers together along the path in a way that performs better than tweening each follower independently (plus it's easier). If your goal is to tween all followers around a CirclePath2D twice completely, you could just add 2 to the `progress` or `rawProgress` value or use a relative value in the tween, like:
`TweenLite.to(myCircle, 5, {progress:"2"}); //or myCircle.progress + 2`

Implementation
`public function get progress():Number`
`public function set progress(value:Number):void`

See also

rawProgress

rawProgress | property |

`rawProgress:Number` [read-write]

Identical to `progress` except that the value is not re-interpolated between 0 and 1. For example, if you set the motion path's `rawProgress` to 2.1, `progress` would be 0.1 (the corresponding value between 0 and 1), essentially wrapping it. If `rawProgress` is set to -3.4, `progress` would be 0.6. Setting `progress` affects `rawProgress` and vice versa. For example:
`myPath.progress = 2.1;
trace(myPath.progress); //traces "0.1"
trace(myPath.rawProgress); //traces "2.1"
` Either property can be used to move all followers along the path. Unlike a PathFollower's `progress` or `rawProgress`, this value is not absolute for motion paths - it simply facilitates relative movement of followers together along the path in a way that performs better than tweening each follower independently (plus it's easier). If your goal is to tween all followers around a CirclePath2D twice completely, for example, you could just add 2 to the `progress` or `rawProgress` value or use a relative value in the tween, like:
`TweenLite.to(myCircle, 5, {rawProgress:"2"}); //or myCircle.rawProgress + 2`

Implementation
`public function get rawProgress():Number`
`public function set rawProgress(value:Number):void`

See also

progress

rotation | property |

`rotation:Number` [read-write]

Implementation
`public function get rotation():Number`
`public function set rotation(value:Number):void`

scaleX | property |

`scaleX:Number` [read-write]

Implementation
`public function get scaleX():Number`
`public function set scaleX(value:Number):void`

scaleY | property |

`scaleY:Number` [read-write]

Implementation
`public function get scaleY():Number`
`public function set scaleY(value:Number):void`

targets | property |

`targets:Array` [read-only]

Returns an array of all target instances associated with the PathFollowers of this path

Implementation
`public function get targets():Array`

visible | property |

`visible:Boolean` [read-write]

Implementation
`public function get visible():Boolean`
`public function set visible(value:Boolean):void`

width | property |

`width:Number` [read-write]

Implementation
`public function get width():Number`
`public function set width(value:Number):void`

x | property |

`x:Number` [read-write]

Implementation
`public function get x():Number`
`public function set x(value:Number):void`

y | property |

`y:Number` [read-write]

Implementation
`public function get y():Number`
`public function set y(value:Number):void`
Method detail

addFollower | () | method

`public function addFollower(target:*, progress:Number = 0, autoRotate:Boolean = false, rotationOffset:Number = 0):PathFollower`

Adds a follower to the path, optionally setting it to a particular progress position. If the target isn't a PathFollower instance already, one will be created for it. The target can be any object that has x and y properties.

Parameters

| `target:*` — Any object that has x and y properties that you'd like to follow the path. Existing PathFollower instances are allowed.
| `progress:Number` (default = `0`)`` — The progress position at which the target should be placed initially (0 by default)
| `autoRotate:Boolean` (default = `false`)`` — When `autoRotate` is `true`, the target will automatically be rotated so that it is oriented to the angle of the path. To offset this value (like to always add 90 degrees for example), use the `rotationOffset` property.
| `rotationOffset:Number` (default = `0`)`` — When `autoRotate` is `true`, this value will always be added to the resulting `rotation` of the target.

Returns

| `PathFollower` — A PathFollower instance associated with the target (you can tween this PathFollower's `progress` property to move it along the path).

distribute | () | method |

`public function distribute(targets:Array = null, min:Number = 0, max:Number = 1, autoRotate:Boolean = false, rotationOffset:Number = 0):void`

Distributes objects evenly along the MotionPath. You can optionally define minimum and maximum `progress` values between which the objects will be distributed. For example, if you want them distributed from the very beginning of the path to the middle, you would do:
`path.distribute([mc1, mc2, mc3], 0, 0.5);
` As it loops through the `targets` array, if a target is found for which a PathFollower doesn't exist, one will automatically be created and added to the path. The `targets` array can be populated with PathFollowers or DisplayObjects or Points or pretty much any object.

Parameters

| `targets:Array` (default = `null`)`` — An array of targets (PathFollowers, DisplayObjects, Points, or pretty much any object) that should be distributed evenly along the MotionPath. As it loops through the `targets` array, if a target is found for which a PathFollower doesn't exist, one will automatically be created and added to the path.
| `min:Number` (default = `0`)`` — The minimum `progress` value at which the targets will begin being distributed. This value will always be between 0 and 1. For example, if the targets should be distributed from the midpoint of the path through the end, the `min` parameter would be 0.5 and the `max` parameter would be 1.
| `max:Number` (default = `1`)`` — The maximum `progress` value where the targets will end distribution. This value will always be between 0 and 1. For example, if the targets should be distributed from the midpoint of the path through the end, the `min` parameter would be 0.5 and the `max` parameter would be 1.
| `autoRotate:Boolean` (default = `false`)`` — When `autoRotate` is `true`, the target will automatically be rotated so that it is oriented to the angle of the path. To offset this value (like to always add 90 degrees for example), use the `rotationOffset` property.
| `rotationOffset:Number` (default = `0`)`` — When `autoRotate` is `true`, this value will always be added to the resulting `rotation` of the target. For example, to always add 90 degrees to the autoRotation, `rotationOffset` would be 90.

getFollower | () | method |

`public function getFollower(target:Object):PathFollower`

Returns the PathFollower instance associated with a particular target or null if none exists.

Parameters

| `target:Object` — The target whose PathFollower instance you want returned.

Returns

| `PathFollower` — PathFollower instance

lineStyle | () | method |

`public function lineStyle(thickness:Number = 1, color:uint = 0x666666, alpha:Number = 1, pixelHinting:Boolean = false, scaleMode:String = "none", caps:String = null, joints:String = null, miterLimit:Number = 3, skipRedraw:Boolean = false):void`

Sets the line style for the path which you will only see if you add the path to the display list with something like addChild() and make sure the visible property is true. For example, to make a CirclePath2D visible with a red line red that's 3 pixels thick, you could do:
`var myCircle:CirclePath2D = new CirclePath2D(150, 150, 100);
myCircle.lineStyle(3, 0xFF0000);
addChild(myCircle);
`

Parameters

| `thickness:Number` (default = `1`)`` — line thickness
| `color:uint` (default = `0x666666`)`` — line color
| `alpha:Number` (default = `1`)`` — line alpha
| `pixelHinting:Boolean` (default = `false`)`` — pixel hinting
| `scaleMode:String` (default = "`none`")`` — scale mode
| `caps:String` (default = `null`)`` — caps
| `joints:String` (default = `null`)`` — joints
| `miterLimit:Number` (default = `3`)`` — miter limit
| `skipRedraw:Boolean` (default = `false`)`` — if true, the redraw will be skipped.

removeAllFollowers | () | method |

`public function removeAllFollowers():void`

Removes all followers.

removeFollower | () | method |

`public function removeFollower(target:*):void`

Removes the target as a follower. The target can be a PathFollower instance or the target associated with one of the PathFollower instances.

Parameters

| `target:*` — the target or PathFollower instance to remove.

renderObjectAt | () | method |

`public function renderObjectAt(target:Object, progress:Number, autoRotate:Boolean = false, rotationOffset:Number = 0):void`

Positions any object with x and y properties on the path at a specific progress position. For example, to position `mc` in the middle of the path, you would do:
`myPath.renderObjectAt(mc, 0.5);`
Some paths have methods to translate other meaningful information into a progress value, like for a `CirclePath2D` you can get the progress associated with the 90-degree position with the `angleToPosition()` method like this:
`myCircle.renderObjectAt(mc, myCircle.angleToProgress(90));`

Parameters

| `target:Object` — The target object to position
| `progress:Number` — The progress value (typically between 0 and 1 where 0 is the beginning of the path, 0.5 is in the middle, and 1 is at the end)
| `autoRotate:Boolean` (default = `false`)`` — When `autoRotate` is `true`, the target will automatically be rotated so that it is oriented to the angle of the path. To offset this value (like to always add 90 degrees for example), use the `rotationOffset` property.
| `rotationOffset:Number` (default = `0`)`` — When `autoRotate` is `true`, this value will always be added to the resulting `rotation` of the target.

update | () | method |

`public function update(event:Event = null):void`

Forces the MotionPath to re-render itself and all of its followers.

Parameters

| `event:Event` (default = `null`)`` — An optional Event that is accepted just to make it easier for use as an event handler (to have it update automatically on every frame, for example, you could add an ENTER_FRAME listener and point it to this method).