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。在我的代码下面，我试图设置缓解效果。我想设置easin，easout，弹跳，旋转等特效应用

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

罗伯特·彭纳写下了著名和常用的缓解算法：通过Kirupa.com上

这里有一个良好的书面教程使用彭纳的缓和作用：

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

您可以用他宽松的算法来缓和效果添加到您的KineticJS动画。

这里有他的算法编码的JavaScript对象中：

// 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; 
    } 
};