JS Tween动画效果研究 : - )Tween公式使用
2013-01-16 17:20 VVG 阅读(13534) 评论(2) 编辑 收藏 举报先看iframe一下DEMO:
DEMO:点击直接查看
Tween中的方法接受4个参数t,b,c,d 。返回值为计算后的当前位置.
t => time(初始记步次数) b => begin(初始位置) c => change(变化量) d => duration(持续次数)
如:
Quad:{ easeIn:function (t, b, c, d) { return c * (t /= d) * t + b; }, easeOut:function (t, b, c, d) { return -c * (t /= d) * (t - 2) + b; }, easeInOut:function (t, b, c, d) { if ((t /= d / 2) < 1) return c / 2 * t * t + b; return -c / 2 * ((--t) * (t - 2) - 1) + b; } }
公式的原理是神马,我也搞不懂,看起来好高深,我只知道用。。。拿来主义,呵呵。
我们知道了其中的参数的意思,就可以写一个通用的move函数,用的时候只要传递Tween方法即可,我写的方法如下:
function MoveTo(options) { //参数o,t,b,c,d ***** o为移动对象 t => time(初始记步次数) b => begin(初始位置) c => change(变化量) d => duration(持续次数) var o = options.o, // 移动对象 t = options.t || 0, // 初始步进 lb = options.lb || 0, // 初始left距离 tb = options.tb || 0, // 初始top距离 lc = options.lc || 500, // left变化的距离 tc = options.tc || 0, // top变化的距离 d = options.d || 500, // 变化次数,次数越多速度越慢 tween = options.tween || Tween.Elastic.easeOut; // 移动方式,套用公式 (function () { if (o) { if (lc > 0){ o.style.left = Math.ceil(tween(t, lb, lc, d)) + "px"; } if (tc > 0) { o.style.top = Math.ceil(tween(t, tb, tc, d)) + "px"; } if (t < d) { t++; setTimeout(arguments.callee, 10); } } })() }
动画与绘制轨迹曲线的代码如下:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Tween动画效果</title> <style type="text/css"> #vvg { text-align: center; font-size: 16px; font-weight: bold; } #box { width: 520px; height: 50px; border: 1px solid #333; margin: 10px auto; position: relative; } #sbox { width: 20px; height: 50px; position: absolute; left: 0; background: red; } #graph{ border: 1px solid #ccc; background: #272424;} #vvg .radios{width: 520px; margin: 5px auto; font-weight: normal; text-align: left; overflow: hidden;} #vvg .radios label{ width:103px; float: left;} #vvg .row1{ background: #cccccc;} #vvg .row2{ background: #b6b6b6; margin-top: 10px;} #vvg .btn{padding: 5px 40px;} </style> </head> <body> <div id="vvg"> <div id="box"> <div id="sbox"> </div> </div> <canvas id="graph" width="522px" height="500">你的浏览器不支持canvas</canvas> <div class="radios row1" id="radio_1"> <label><input type="radio" value="Linear" name="tname" checked>Linear</label> <label><input type="radio" value="Quad" name="tname">Quad </label> <label><input type="radio" value="Cubic" name="tname">Cubic </label> <label><input type="radio" value="Quart" name="tname">Quart </label> <label><input type="radio" value="Quint" name="tname">Quint</label> <label><input type="radio" value="Sine" name="tname">Sine</label> <label><input type="radio" value="Expo" name="tname">Expo</label> <label><input type="radio" value="Circ" name="tname">Circ</label> <label><input type="radio" value="Elastic" name="tname">Elastic</label> <label><input type="radio" value="Back" name="tname">Back</label> <label><input type="radio" value="Bounce" name="tname">Bounce</label> </div> <div class="radios row2" id="radio_2"> <label><input type="radio" value="easeIn" name="tname2" checked>easeIn</label> <label><input type="radio" value="easeOut" name="tname2">easeOut</label> <label><input type="radio" value="easeInOut" name="tname2">easeInOut</label> </div> <div><input type="button" value="运 行" class="btn" id="run"></div> </div> <script type="text/javascript"> // 快捷选择函数 function $(arg, context) { var tagAll, n, eles = [], i, sub = arg.substring(1); context = context || document; if (typeof arg == 'string') { switch (arg.charAt(0)) { case '#': return document.getElementById(sub); break; case '.': if (context.getElementsByClassName) return context.getElementsByClassName(sub); tagAll = $('*', context); n = tagAll.length; for (i = 0; i < n; i++) { if (tagAll[i].className.indexOf(sub) > -1) eles.push(tagAll[i]); } return eles; break; default: return context.getElementsByTagName(arg); break; } } } var Tween = { Linear:function (t, b, c, d) { return c * t / d + b; }, Quad:{ easeIn:function (t, b, c, d) { return c * (t /= d) * t + b; }, easeOut:function (t, b, c, d) { return -c * (t /= d) * (t - 2) + b; }, easeInOut:function (t, b, c, d) { if ((t /= d / 2) < 1) return c / 2 * t * t + b; return -c / 2 * ((--t) * (t - 2) - 1) + b; } }, Cubic:{ easeIn:function (t, b, c, d) { return c * (t /= d) * t * t + b; }, easeOut:function (t, b, c, d) { return c * ((t = t / d - 1) * t * t + 1) + b; }, easeInOut: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; } }, Quart:{ easeIn:function (t, b, c, d) { return c * (t /= d) * t * t * t + b; }, easeOut:function (t, b, c, d) { return -c * ((t = t / d - 1) * t * t * t - 1) + b; }, easeInOut: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; } }, Quint:{ easeIn:function (t, b, c, d) { return c * (t /= d) * t * t * t * t + b; }, easeOut:function (t, b, c, d) { return c * ((t = t / d - 1) * t * t * t * t + 1) + b; }, easeInOut: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; } }, Sine:{ easeIn:function (t, b, c, d) { return -c * Math.cos(t / d * (Math.PI / 2)) + c + b; }, easeOut:function (t, b, c, d) { return c * Math.sin(t / d * (Math.PI / 2)) + b; }, easeInOut:function (t, b, c, d) { return -c / 2 * (Math.cos(Math.PI * t / d) - 1) + b; } }, Expo:{ easeIn:function (t, b, c, d) { return (t == 0) ? b : c * Math.pow(2, 10 * (t / d - 1)) + b; }, easeOut:function (t, b, c, d) { return (t == d) ? b + c : c * (-Math.pow(2, -10 * t / d) + 1) + b; }, easeInOut: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; } }, Circ:{ easeIn:function (t, b, c, d) { return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b; }, easeOut:function (t, b, c, d) { return c * Math.sqrt(1 - (t = t / d - 1) * t) + b; }, easeInOut: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; } }, Elastic:{ easeIn:function (t, b, c, d, a, p) { if (t == 0) return b; if ((t /= d) == 1) return b + c; if (!p) p = d * .3; if (!a || 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; }, easeOut:function (t, b, c, d, a, p) { if (t == 0) return b; if ((t /= d) == 1) return b + c; if (!p) p = d * .3; if (!a || 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); }, easeInOut:function (t, b, c, d, a, p) { if (t == 0) return b; if ((t /= d / 2) == 2) return b + c; if (!p) p = d * (.3 * 1.5); if (!a || 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; } }, Back:{ easeIn:function (t, b, c, d, s) { if (s == undefined) s = 1.70158; return c * (t /= d) * t * ((s + 1) * t - s) + b; }, easeOut: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; }, easeInOut: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; } }, Bounce:{ easeIn:function (t, b, c, d) { return c - Tween.Bounce.easeOut(d - t, 0, c, d) + b; }, easeOut: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; } }, easeInOut:function (t, b, c, d) { if (t < d / 2) return Tween.Bounce.easeIn(t * 2, 0, c, d) * .5 + b; else return Tween.Bounce.easeOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b; } } } //Tween中的方法接受4个参数t,b,c,d 。t为初始时间 b、c、d三个参数(即初始值,变化量,持续时间)。返回值为当前位置 //t => time(初始记步次数) b => begin(初始位置) c => change(变化量) d => duration(持续次数) /* 先通过上面的坐标实例说一下算法原理: x轴是时间,y轴是当前值,b是y轴的初始值,x轴的初始值是0,t是当前时间。当t(x轴)逐渐增加到达d时,当前值(y轴)会到达目标值(b+c)。 想详细理解的话可以找资料看看吧(貌似跟数学关系比较大)。 下面就介绍如何使用这个Tween了,首先b、c、d三个参数(即初始值,变化量,持续时间)在缓动开始前,是需要先确定好的。 举一个简单的例子,一个div要向右缓动,left初始值是50,那么b就是50,要向右移动100,那c就是100,如果知道的是目标值,例如要向右移动到150,那就把目标值150减初始值b就是变化量c了。 至于d的设置就比较灵活,只要符合t是从0向d递增(或递减)就可以了。 d跟步长配合使用来设置持续时间,例如d设置为100,如果设置步长是1,那么从0到100就有100步,即分100次来完成这个过程,步数越多那么持续时间就越长。 至于t的变化相当于时间的变化,一般是均匀变化的,每次变化都增加一个步长,当t从0递增(或递减)到d时,缓动就结束了。 要注意的是t是从0开始的,设置步长时必须确定t确实能到达d,如果上面的步长是3,那么t就永远都到不了d了。更好的处理是当t等于或超过d之后,就停止定时器并设置当前值为目标值。 */ // 获取radio值 var radio_1 = function(){ var radios = $('input',$('#radio_1')); for(var i = 0,n=radios.length;i<n;i++){ if(radios[i].checked == true){ return radios[i].value; } } }; var radio_2 = function(){ var radios = $('input',$('#radio_2')); for(var i = 0,n=radios.length;i<n;i++){ if(radios[i].checked == true){ return radios[i].value; } } }; // 移动动画 function MoveTo(options) { //参数o,t,b,c,d ***** o为移动对象 t => time(初始记步次数) b => begin(初始位置) c => change(变化量) d => duration(持续次数) var o = options.o, // 移动对象 t = options.t || 0, // 初始步进 lb = options.lb || 0, // 初始left距离 tb = options.tb || 0, // 初始top距离 lc = options.lc || 500, // left变化的距离 tc = options.tc || 0, // top变化的距离 d = options.d || 500, // 变化次数,次数越多速度越慢 tween = options.tween || Tween.Elastic.easeOut; // 移动方式,套用公式 // 绘图处=============================不用绘图可去掉 var canvas = document.getElementById('graph'); var context = canvas.getContext('2d'); context.clearRect(0,0,500,500); // ================================== end (function () { if (o) { if (lc > 0){ o.style.left = Math.ceil(tween(t, lb, lc, d)) + "px"; // 绘图区域开始,可以去掉 ============================== drawPoint({ canvas:canvas, left:Math.ceil(t*5), top: Math.ceil(tween(t, lb, lc, d)) }) // 绘图区域结束 ====================================== } if (tc > 0) { o.style.top = Math.ceil(tween(t, tb, tc, d)) + "px"; } if (t < d) { t++; setTimeout(arguments.callee, 10); } } })() } // 绘制曲线图 function drawPoint(options){ var canvas = options.canvas; //画布 var left = options.left; // time var top = options.top; // 当前值 var context = canvas.getContext('2d'); // 绘制点 context.fillStyle = '#fff'; context.fillRect(left,top,2,2); } $("#run").onclick = function(){ var div = document.getElementById('sbox'); var tween1 = radio_1(); var tween2 = radio_2(); if(!!Tween[tween1][tween2]){ var tween = Tween[tween1][tween2]; }else{ tween = Tween[tween1]; } var options = { o:div, lc:500, d:100, tween:tween } MoveTo(options); } </script> </body> </html>
详细请参考: cloudgamer Tween算法及缓动效果
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