morpheus/src/easings.js

A Brilliant Animator

/* The equations defined here are open source under BSD License.
 * http://www.robertpenner.com/easing_terms_of_use.html (c) 2003 Robert Penner
 * Adapted to single time-based by
 * Brian Crescimanno <brian.crescimanno@gmail.com>
 * Ken Snyder <kendsnyder@gmail.com>
 */
var easings = {
  easeOut: function (t) {
    return Math.sin(t * Math.PI / 2);
  }

  , easeOutStrong: function (t) {
    return (t == 1) ? 1 : 1 - Math.pow(2, -10 * t);
  }

  , easeIn: function (t) {
    return t * t;
  }

  , easeInStrong: function (t) {
    return (t == 0) ? 0 : Math.pow(2, 10 * (t - 1));
  }

  , easeOutBounce: function(pos) {
    if ((pos) < (1/2.75)) {
      return (7.5625*pos*pos);
    } else if (pos < (2/2.75)) {
      return (7.5625*(pos-=(1.5/2.75))*pos + .75);
    } else if (pos < (2.5/2.75)) {
      return (7.5625*(pos-=(2.25/2.75))*pos + .9375);
    } else {
      return (7.5625*(pos-=(2.625/2.75))*pos + .984375);
    }
  }

  , easeInBack: function(pos){
    var s = 1.70158;
    return (pos)*pos*((s+1)*pos - s);
  }

  , easeOutBack: function(pos){
    var s = 1.70158;
    return (pos=pos-1)*pos*((s+1)*pos + s) + 1;
  }

  , bounce: function (t) {
    if (t < (1 / 2.75)) {
      return 7.5625 * t * t;
    }
    if (t < (2 / 2.75)) {
      return 7.5625 * (t -= (1.5 / 2.75)) * t + 0.75;
    }
    if (t < (2.5 / 2.75)) {
      return 7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375;
    }
    return 7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375;
  }

  , bouncePast: function (pos) {
    if (pos < (1 / 2.75)) {
      return (7.5625 * pos * pos);
    } else if (pos < (2 / 2.75)) {
      return 2 - (7.5625 * (pos -= (1.5 / 2.75)) * pos + .75);
    } else if (pos < (2.5 / 2.75)) {
      return 2 - (7.5625 * (pos -= (2.25 / 2.75)) * pos + .9375);
    } else {
      return 2 - (7.5625 * (pos -= (2.625 / 2.75)) * pos + .984375);
    }
  }

  , swingTo: function(pos) {
    var s = 1.70158;
    return (pos -= 1) * pos * ((s + 1) * pos + s) + 1;
  }

  , swingFrom: function (pos) {
    var s = 1.70158;
    return pos * pos * ((s + 1) * pos - s);
  }

  , elastic: function(pos) {
    return -1 * Math.pow(4, -8 * pos) * Math.sin((pos * 6 - 1) * (2 * Math.PI) / 2) + 1;
  }

  , spring: function(pos) {
    return 1 - (Math.cos(pos * 4.5 * Math.PI) * Math.exp(-pos * 6));
  }

  , blink: function(pos, blinks) {
    return Math.round(pos*(blinks||5)) % 2;
  }

  , pulse: function(pos, pulses) {
    return (-Math.cos((pos*((pulses||5)-.5)*2)*Math.PI)/2) + .5;
  }

  , wobble: function(pos) {
    return (-Math.cos(pos*Math.PI*(9*pos))/2) + 0.5;
  }

  , sinusoidal: function(pos) {
    return (-Math.cos(pos*Math.PI)/2) + 0.5;
  }

  , flicker: function(pos) {
    var pos = pos + (Math.random()-0.5)/5;
    return easings.sinusoidal(pos < 0 ? 0 : pos > 1 ? 1 : pos);
  }

  , mirror: function(pos) {
    if (pos < 0.5)
    return easings.sinusoidal(pos*2);
    else
    return easings.sinusoidal(1-(pos-0.5)*2);
  }

};