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<h1 class="page-title">Source: tween/Easing.js</h1>
<section>
<article>
<pre class="sunlight-highlight-javascript linenums">/* jshint curly: false */
/**
* @author Richard Davey <rich@photonstorm.com>
* @copyright 2014 Photon Storm Ltd.
* @license {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/
/**
* A collection of easing methods defining ease-in ease-out curves.
*
* @class Phaser.Easing
*/
Phaser.Easing = {
/**
* Linear easing.
*
* @class Phaser.Easing.Linear
*/
Linear: {
/**
* Ease-in.
*
* @method Phaser.Easing.Linear#In
* @param {number} k - The value to be tweened.
* @returns {number} k^2.
*/
None: function ( k ) {
return k;
}
},
/**
* Quadratic easing.
*
* @class Phaser.Easing.Quadratic
*/
Quadratic: {
/**
* Ease-in.
*
* @method Phaser.Easing.Quadratic#In
* @param {number} k - The value to be tweened.
* @returns {number} k^2.
*/
In: function ( k ) {
return k * k;
},
/**
* Ease-out.
*
* @method Phaser.Easing.Quadratic#Out
* @param {number} k - The value to be tweened.
* @returns {number} k* (2-k).
*/
Out: function ( k ) {
return k * ( 2 - k );
},
/**
* Ease-in/out.
*
* @method Phaser.Easing.Quadratic#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
if ( ( k *= 2 ) < 1 ) return 0.5 * k * k;
return - 0.5 * ( --k * ( k - 2 ) - 1 );
}
},
/**
* Cubic easing.
*
* @class Phaser.Easing.Cubic
*/
Cubic: {
/**
* Cubic ease-in.
*
* @method Phaser.Easing.Cubic#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
return k * k * k;
},
/**
* Cubic ease-out.
*
* @method Phaser.Easing.Cubic#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
return --k * k * k + 1;
},
/**
* Cubic ease-in/out.
*
* @method Phaser.Easing.Cubic#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
if ( ( k *= 2 ) < 1 ) return 0.5 * k * k * k;
return 0.5 * ( ( k -= 2 ) * k * k + 2 );
}
},
/**
* Quartic easing.
*
* @class Phaser.Easing.Quartic
*/
Quartic: {
/**
* Quartic ease-in.
*
* @method Phaser.Easing.Quartic#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
return k * k * k * k;
},
/**
* Quartic ease-out.
*
* @method Phaser.Easing.Quartic#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
return 1 - ( --k * k * k * k );
},
/**
* Quartic ease-in/out.
*
* @method Phaser.Easing.Quartic#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
if ( ( k *= 2 ) < 1) return 0.5 * k * k * k * k;
return - 0.5 * ( ( k -= 2 ) * k * k * k - 2 );
}
},
/**
* Quintic easing.
*
* @class Phaser.Easing.Quintic
*/
Quintic: {
/**
* Quintic ease-in.
*
* @method Phaser.Easing.Quintic#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
return k * k * k * k * k;
},
/**
* Quintic ease-out.
*
* @method Phaser.Easing.Quintic#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
return --k * k * k * k * k + 1;
},
/**
* Quintic ease-in/out.
*
* @method Phaser.Easing.Quintic#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
if ( ( k *= 2 ) < 1 ) return 0.5 * k * k * k * k * k;
return 0.5 * ( ( k -= 2 ) * k * k * k * k + 2 );
}
},
/**
* Sinusoidal easing.
*
* @class Phaser.Easing.Sinusoidal
*/
Sinusoidal: {
/**
* Sinusoidal ease-in.
*
* @method Phaser.Easing.Sinusoidal#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
return 1 - Math.cos( k * Math.PI / 2 );
},
/**
* Sinusoidal ease-out.
*
* @method Phaser.Easing.Sinusoidal#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
return Math.sin( k * Math.PI / 2 );
},
/**
* Sinusoidal ease-in/out.
*
* @method Phaser.Easing.Sinusoidal#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
return 0.5 * ( 1 - Math.cos( Math.PI * k ) );
}
},
/**
* Exponential easing.
*
* @class Phaser.Easing.Exponential
*/
Exponential: {
/**
* Exponential ease-in.
*
* @method Phaser.Easing.Exponential#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
return k === 0 ? 0 : Math.pow( 1024, k - 1 );
},
/**
* Exponential ease-out.
*
* @method Phaser.Easing.Exponential#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
return k === 1 ? 1 : 1 - Math.pow( 2, - 10 * k );
},
/**
* Exponential ease-in/out.
*
* @method Phaser.Easing.Exponential#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
if ( k === 0 ) return 0;
if ( k === 1 ) return 1;
if ( ( k *= 2 ) < 1 ) return 0.5 * Math.pow( 1024, k - 1 );
return 0.5 * ( - Math.pow( 2, - 10 * ( k - 1 ) ) + 2 );
}
},
/**
* Circular easing.
*
* @class Phaser.Easing.Circular
*/
Circular: {
/**
* Circular ease-in.
*
* @method Phaser.Easing.Circular#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
return 1 - Math.sqrt( 1 - k * k );
},
/**
* Circular ease-out.
*
* @method Phaser.Easing.Circular#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
return Math.sqrt( 1 - ( --k * k ) );
},
/**
* Circular ease-in/out.
*
* @method Phaser.Easing.Circular#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
if ( ( k *= 2 ) < 1) return - 0.5 * ( Math.sqrt( 1 - k * k) - 1);
return 0.5 * ( Math.sqrt( 1 - ( k -= 2) * k) + 1);
}
},
/**
* Elastic easing.
*
* @class Phaser.Easing.Elastic
*/
Elastic: {
/**
* Elastic ease-in.
*
* @method Phaser.Easing.Elastic#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
var s, a = 0.1, p = 0.4;
if ( k === 0 ) return 0;
if ( k === 1 ) return 1;
if ( !a || a < 1 ) { a = 1; s = p / 4; }
else s = p * Math.asin( 1 / a ) / ( 2 * Math.PI );
return - ( a * Math.pow( 2, 10 * ( k -= 1 ) ) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) );
},
/**
* Elastic ease-out.
*
* @method Phaser.Easing.Elastic#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
var s, a = 0.1, p = 0.4;
if ( k === 0 ) return 0;
if ( k === 1 ) return 1;
if ( !a || a < 1 ) { a = 1; s = p / 4; }
else s = p * Math.asin( 1 / a ) / ( 2 * Math.PI );
return ( a * Math.pow( 2, - 10 * k) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) + 1 );
},
/**
* Elastic ease-in/out.
*
* @method Phaser.Easing.Elastic#InOut
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
InOut: function ( k ) {
var s, a = 0.1, p = 0.4;
if ( k === 0 ) return 0;
if ( k === 1 ) return 1;
if ( !a || a < 1 ) { a = 1; s = p / 4; }
else s = p * Math.asin( 1 / a ) / ( 2 * Math.PI );
if ( ( k *= 2 ) < 1 ) return - 0.5 * ( a * Math.pow( 2, 10 * ( k -= 1 ) ) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) );
return a * Math.pow( 2, -10 * ( k -= 1 ) ) * Math.sin( ( k - s ) * ( 2 * Math.PI ) / p ) * 0.5 + 1;
}
},
/**
* Back easing.
*
* @class Phaser.Easing.Back
*/
Back: {
/**
* Back ease-in.
*
* @method Phaser.Easing.Back#In
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
In: function ( k ) {
var s = 1.70158;
return k * k * ( ( s + 1 ) * k - s );
},
/**
* Back ease-out.
*
* @method Phaser.Easing.Back#Out
* @param {number} k - The value to be tweened.
* @returns {number} The tweened value.
*/
Out: function ( k ) {
var s = 1.70158;
return --k * k * ( ( s + 1 ) * k + s ) + 1;
},
/**
* Back ease-in/out.
*