Kinetic JS：在动画中应用缓动效果

Question

任何人都知道如何在动画中应用缓动效果。在我试图设置缓动效果的代码下方。我想设置 easin,easout,bouncing,spin 等效果应用

var yPos = myShape.getAttr('y'),
    xPos = myShape.getAttr('x'),
    maxX = 1000,
    maxY = 1000,
    yIncreasing = true,
    xIncreasing = true; //lets assume myShape resides somewhere below the max

var anim = new Kinetic.Animation(function(frame) {
    /* move the shape back and fourth in a y direction */
    if (yPos < maxY && yIncreasing)  {
        hexagon.setY(yPos++);
    } else {
        if (yPos < 1) {
            yIncreasing = true;
            hexagon.setY(yPos++);
        } else {
            hexagon.setY(yPos--);
            yIncreasing = false;
        }
    } 

    /* move the shape back and fourth in a x direction */
    if (xPos < maxX && xIncreasing) {
        hexagon.setX(xPos++);
    } else {
        if (xPos < 1) {
            xIncreasing = true;
            hexagon.setX(xPos++);
        } else {
            hexagon.setX(xPos--);
            xIncreasing = false;
        }
    } 
}, layer);

Answer 1

Robert Penner 编写了著名且常用的缓动算法：

这是 Kirupa.com 编写的关于使用 Penner 缓动函数的精心编写的教程：

http://www.kirupa.com/html5/animating_with_easing_functions_in_javascript.htm

您可以使用他的缓动算法将缓动添加到您的 KineticJS 动画中。

这是他在 javascript 对象中编码的算法：

// t: current time, 
// b: beginning value, 
// c: total change in value over the duration, 
// d: duration,
// return value: the 'eased' value between b and b+c at this current time t

var easings={

  easeInQuad: function ( t, b, c, d) {
    return c*(t/=d)*t + b;
  },
  easeOutQuad: function ( t, b, c, d) {
    return -c *(t/=d)*(t-2) + b;
  },
  easeInOutQuad: function ( t, b, c, d) {
    if ((t/=d/2) < 1) return c/2*t*t + b;
    return -c/2 * ((--t)*(t-2) - 1) + b;
  },
  easeInCubic: function ( t, b, c, d) {
    return c*(t/=d)*t*t + b;
  },
  easeOutCubic: function ( t, b, c, d) {
    return c*((t=t/d-1)*t*t + 1) + b;
  },
  easeInOutCubic: function ( t, b, c, d) {
    if ((t/=d/2) < 1) return c/2*t*t*t + b;
    return c/2*((t-=2)*t*t + 2) + b;
  },
  easeInQuart: function ( t, b, c, d) {
    return c*(t/=d)*t*t*t + b;
  },
  easeOutQuart: function ( t, b, c, d) {
    return -c * ((t=t/d-1)*t*t*t - 1) + b;
  },
  easeInOutQuart: function ( t, b, c, d) {
    if ((t/=d/2) < 1) return c/2*t*t*t*t + b;
    return -c/2 * ((t-=2)*t*t*t - 2) + b;
  },
  easeInQuint: function ( t, b, c, d) {
    return c*(t/=d)*t*t*t*t + b;
  },
  easeOutQuint: function ( t, b, c, d) {
    return c*((t=t/d-1)*t*t*t*t + 1) + b;
  },
  easeInOutQuint: function ( t, b, c, d) {
    if ((t/=d/2) < 1) return c/2*t*t*t*t*t + b;
    return c/2*((t-=2)*t*t*t*t + 2) + b;
  },
  easeInSine: function ( t, b, c, d) {
    return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
  },
  easeOutSine: function ( t, b, c, d) {
    return c * Math.sin(t/d * (Math.PI/2)) + b;
  },
  easeInOutSine: function ( t, b, c, d) {
    return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
  },
  easeInExpo: function ( t, b, c, d) {
    return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;
  },
  easeOutExpo: function ( t, b, c, d) {
    return (t==d) ? b+c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
  },
  easeInOutExpo: function ( t, b, c, d) {
    if (t==0) return b;
    if (t==d) return b+c;
    if ((t/=d/2) < 1) return c/2 * Math.pow(2, 10 * (t - 1)) + b;
    return c/2 * (-Math.pow(2, -10 * --t) + 2) + b;
  },
  easeInCirc: function ( t, b, c, d) {
    return -c * (Math.sqrt(1 - (t/=d)*t) - 1) + b;
  },
  easeOutCirc: function ( t, b, c, d) {
    return c * Math.sqrt(1 - (t=t/d-1)*t) + b;
  },
  easeInOutCirc: function ( t, b, c, d) {
    if ((t/=d/2) < 1) return -c/2 * (Math.sqrt(1 - t*t) - 1) + b;
    return c/2 * (Math.sqrt(1 - (t-=2)*t) + 1) + b;
  },
  easeInElastic: function ( t, b, c, d) {
    var s=1.70158;var p=0;var a=c;
    if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
    if (a < Math.abs(c)) { a=c; var s=p/4; }
    else var s = p/(2*Math.PI) * Math.asin (c/a);
    return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
  },
  easeOutElastic: function ( t, b, c, d) {
    var s=1.70158;var p=0;var a=c;
    if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
    if (a < Math.abs(c)) { a=c; var s=p/4; }
    else var s = p/(2*Math.PI) * Math.asin (c/a);
    return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
  },
  easeInOutElastic: function ( t, b, c, d) {
    var s=1.70158;var p=0;var a=c;
    if (t==0) return b;  if ((t/=d/2)==2) return b+c;  if (!p) p=d*(.3*1.5);
    if (a < Math.abs(c)) { a=c; var s=p/4; }
    else var s = p/(2*Math.PI) * Math.asin (c/a);
    if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
    return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
  },
  easeInBack: function ( t, b, c, d, s) {
    if (s == undefined) s = 1.70158;
    return c*(t/=d)*t*((s+1)*t - s) + b;
  },
  easeOutBack: function ( t, b, c, d, s) {
    if (s == undefined) s = 1.70158;
    return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
  },
  easeInOutBack: function ( t, b, c, d, s) {
    if (s == undefined) s = 1.70158; 
    if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
    return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
  },
  easeInBounce: function ( t, b, c, d) {
    return c - this.easing.easeOutBounce ( d-t, 0, c, d) + b;
  },
  easeOutBounce: function ( t, b, c, d) {
    if ((t/=d) < (1/2.75)) {
      return c*(7.5625*t*t) + b;
    } else if (t < (2/2.75)) {
      return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;
    } else if (t < (2.5/2.75)) {
      return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;
    } else {
      return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;
    }
  },
  easeInOutBounce: function ( t, b, c, d) {
    if (t < d/2) return this.easing.easeInBounce ( t*2, 0, c, d) * .5 + b;
    return this.easing.easeOutBounce ( t*2-d, 0, c, d) * .5 + c*.5 + b;
  }
};