牛顿摆是一个1960年代发明的桌面演示装置，五个质量相同的球体由吊绳固定，彼此紧密排列。又叫：牛顿摆球、动量守恒摆球、永动球、物理撞球、碰碰球等。
(function(window,undefined){ window.None || (window.None = {}); //重力加速度 var G=9.8; var PI=Math.PI; //帧频 var FPS=48; /* //IE角度转换 function rorateIt(node,deg){ //取得末变形前矩形的中点 var rect = node.getBoundingClientRect(), cx1 = (rect.right - rect.left) / 2, // center x cy1 = (rect.bottom - rect.top) / 2, // center y deg2rad = Math.PI / 180,//角度转弧度 rad = deg * deg2rad , cos = Math.cos(rad), sin = Math.sin(rad); var ident = "DXImageTransform.Microsoft.Matrix"; node.style.filter = "progid:"+ident +"(M11='1.0',sizingmethod='auto expand')"; //http://www.satzansatz.de/cssd/onhavinglayout.html if(!node.currentStyle.hasLayout){//在IE7中，如果没有获得hasLayout，滤镜会失效 node.style.writingMode = "tb-rl"; } var filter = node.filters.item(ident); // +-------+-------+ // | M11 | M12 | // +-------+-------+ // | M21 | M22 | // +-------+-------+ filter.M11 = cos; filter.M12 = -sin; filter.M21 = sin; filter.M22 = cos; //取得当前中心 rect = node.getBoundingClientRect(); var cx = (rect.right - rect.left) / 2; var cy = (rect.bottom - rect.top) / 2; //调整此元素的坐标系，实现CSS3 transform-origin的功能 node.style.marginLeft = cx1 - cx + "px"; node.style.marginTop = cy1 - cy + "px"; } */ //外部函数引用 //是否IE function isIE(){ return navigator.userAgent.indexOf("MSIE")>-1; } //获取当前样式 function returnStyle(obj,styleName){ var myObj = typeof obj == "string" ? document.getElementById(obj) : obj; if(document.all){ return eval("myObj.currentStyle." + styleName); } else { return eval("document.defaultView.getComputedStyle(myObj,null)." + styleName); } } //外部函数引用 //图片方法 var img=function(src){ var img=new Image(); img.src=src; return img; } //方向类，以垂直向下为0度逆时针为正 var face=function(deg,rad){ //0-360 this.unit='deg'; if(rad)deg=180/PI*deg; this.deg=deg; this.rad=PI/180*this.deg; } //矢量类 var vector=function(size,fx){ var cstrct=this.constructor; this.size=size; this.face=fx||new face(0); fx=this.face; this.toHv=function(){ var h=new cstrct(Math.sin(fx.rad)*size,90); var v=new cstrct(Math.cos(fx.rad)*size,0); return [h,v]; } } //继承，obj:需要从矢量继承的对象,arg:arguments vector.extend=function(obj,arg){ vector.apply(obj,arg); } //矢量合并方法 vector.merger=function(arrvector){ if(arguments.length>1)arrvector=arguments; var cstrct=arrvector[0].constructor; var i=0,ilav=arrvector.length; var sum=[0,0]; for(;i<ilav;i++){ var hv=arrvector[i].toHv(); sum[0]+=hv[0].size; sum[1]+=hv[1].size; } var size=Math.sqrt(sum[0]*sum[0]+sum[1]*sum[1]); var fa=new face(Math.atan(sum[0]/sum[1]),'rad'); return new cstrct(size,fa); } //力类,参数为大小和方向 var force=function(size,face){ this.unit='N'; //继承自矢量 vector.apply(this,arguments); } //加速度类 var a=function(size,face){ this.unit='m/s^2'; vector.extend(this,arguments); } //速度类 var speed=function(size,face){ this.unit='m/s'; vector.extend(this,arguments); } //刚体类,参数(body:IMG对象,m为质量) var rigid=function(body,m){ //一般情况下body为一个img对象，所以暂且只有正方形或长方形两种形式 this.body=body; this.m=m; //质量 this.focus=(this.body instanceof Image)?point(this.body.width/2,this.body.height/2):point(this.body.style.width/2,this.body.style.height/2); this.axis=point(0,0); //轴心位置(point对象) this.force=new force(0); this.a=new a(this.force.size/this.m,this.force.face); this.speed=new speed(0); //设置，可重新设置上面所有参数 this.set=function(prop,value){ this[prop]=value; } this.addForce=function(f){ return this.force=vector.merger(f,this.force); } //旋转 this.rotate=function(face,axis){ axis=axis||this.axis||this.focus; //cx1=returnStyle(this.body,"left"); //cy1=returnStyle(this.body,"left"); var rect=this.body.getBoundingClientRect(), //cx1=rect.left+axis.x, //cy1=rect.top+axis.y, cx1 = (rect.right - rect.left) / 2, cy1 = (rect.bottom - rect.top) / 2, rad=face.rad, cos = Math.cos(rad), sin = Math.sin(rad); if(isIE()){ var ident = "DXImageTransform.Microsoft.Matrix"; this.body.style.filter = "progid:"+ident +"(M11='1.0',sizingmethod='auto expand')"; if(!returnStyle(this.body,"hasLayout")){//在IE7中，如果没有获得hasLayout，滤镜会失效 this.body.style.writingMode = "tb-rl"; } var filter = this.body.filters.item(ident); filter.M11 = cos; filter.M12 = -sin; filter.M21 = sin; filter.M22 = cos; } rect = this.body.getBoundingClientRect(); //var cx=rect.left+axis.x; //var cy=rect.top+axis.y; var cx = (rect.right - rect.left) / 2; var cy = (rect.bottom - rect.top) / 2; //调整此元素的坐标系，实现CSS3 transform-origin的功能 this.body.style.left=parseInt(this.body.style.left,10) + cx1 - cx + "px"; this.body.style.top=parseInt(this.body.style.top,10) + cy1 - cy + "px"; //CSS3 var sdeg="rotate("+face.deg+"deg)"; var paxis=axis.x+"px "+axis.y+"px"; this.body.style.transformOrigin=paxis; this.body.style.MozTransformOrigin=paxis; this.body.style.WebkitTransformOrigin=paxis; this.body.style.OTransformOrigin=paxis; this.body.style.WebkitTransform=sdeg; this.body.style.MozTransform=sdeg; this.body.style.OTransform=sdeg; this.body.style.transform=sdeg; } } //刚体组合 rigid.merger=function(){ } //无弹性绳子类 var rope=function(body,length,maxForce){ this.body=body; this.length=length; this.maxForce=maxForce || Infinity || Number.MAX_VALUE; } //组合体类 var comb=function(arrObject){ } //单摆类 var pendulum=function(ripe,rigid){ } //类单摆 var likePend=function(rigid,fa,time){//刚体,初始角度,摆动频率 var self=this; this.rigid=rigid; this.body=this.rigid.body; this.axis=this.rigid.axis; this.dom=this.rigid.dom; this.m=this.rigid.m; this.rad=fa?fa.rad:fa=new face(PI/6,'rad'); //摆动 //角度30 var fx=fa.rad; //角度平方根 var m=Math.sqrt(fx); //摆动时间1秒 var atime=time||0.5; var fnum=FPS*atime; //单位增量 var fm=m/fnum; //i:角度平方根到0 var i=-m,tid; var g=new a(G); var t=1000/FPS; //o:{s:1,f:30,t:0,fun:callback} :s:(-1,1)速度增加还是减小,f:从多少度,t:到多少度,fun:摆完后运行的函数 this.swing=function(o,fun){ /* var asps=g.size*Math.cos(PI/2-fx)/(24*24*self.m); var fss=new force(asps,new face(fx-PI/2)); this.rigid.force=fss; var a=this.rigid.a; //单位时间内速度的增量 var a1=Math.acos((asps+this.rigid.speed.size)/2) this.rigid.speed=new speed(a1,new face(fx-PI/2)); a2=a1*2;*/ //{s:-1,inc:1} o=o||{s:1}; var y=-o.s*i*i+fx*o.s; if(i>=m){ self.rigid.rotate(new face(0),self.axis); clearTimeout(tid); i=-m; if(fun)fun(); return; } var f=new face(y,'rad'); self.rigid.rotate(f,axis=self.axis); i+=fm; tid=setTimeout(function(){self.swing.call(self,o,fun)},t); } this.moveTo=function(p){ self.body.style.left=p.x+"px"; self.body.style.top=p.y+"px"; } } //世界 None.world=function(param){ //param:{force:[多个force对象]} this.param=param||{}; this.config={ //全局外力 g:new a(G), className:'', width:'100%', height:'100%', left:0, top:-200, arrNav:['about','myWork','site','other','myTools'], imgW:60, imgN:5, sDeg:5, hitSound:'sounds/hit.wav', vol:0.1 } this.init(); }; None.world.prototype={ //初始化 dom:{}, init:function(){ var c=this.config; var p=this.param; //dom var dom=document.createElement("div"); dom.className=c.className; dom.style.position="absolute"; dom.style.width=p.width||c.width; dom.style.height=p.height||c.height; dom.style.left=(p.left||c.left) +"px"; dom.style.top=(p.top||c.top) +"px"; this.dom=dom; document.body.appendChild(this.dom); }, //添加一个刚体 addRigid:function(rigid,p){ if(!(rigid instanceof Array)){ rigid=[rigid]; } if(!p)p=[point(0,0)]; if(!(p instanceof Array))p=[p]; for(var i=0,rl=rigid.length;i<rl;i++){ p[i]=p[i] || p[0]; rigid[i].body.style.position="absolute"; rigid[i].body.style.left=p[i].x+"px"; rigid[i].body.style.top=p[i].y+"px"; this.dom.appendChild(rigid[i].body); } }, //添加一个外作用力 addForce:function(){ }, start:function(){ var p=this.param, c=this.config; var shit=p.hitSound||c.hitSound; var sndHit=new None.sounds(shit); sndHit.volume=p.vol||c.vol; var w=document.documentElement.offsetWidth; var imgWidth=p.imgW||c.imgW;//图片宽度 var imgNum=p.imgN||c.imgN; //图片数量 var jd=p.sDeg||c.sDeg; //最大角度 var es=p.arrNav||c.arrNav; var time=p.time||c.time; var basex=w/2-imgWidth*imgNum/2; var jiaodu=new face(jd); var rig=[],ball=[],pend=[],axis=point(imgWidth/2,0); for(var i=0,el=es.length;i<el;i++){ rig[i]=document.getElementById(es[i]); ball[i]=new rigid(rig[i],1); ball[i].set("axis",axis); pend[i]=new likePend(ball[i],jiaodu,time); } this.addRigid(pend); resize(); if(!isIE())swing(); window.onresize=resize; function hit(v){ sndHit.play(); } function swing(){ var runfun=arguments.callee; var last=pend.length-1; if(p.hitSound)hit(0); pend[0].swing({s:1},function(){ if(p.hitSound)hit(1); pend[last].swing({s:-1},runfun); }); } function resize(){ var w=document.documentElement.offsetWidth; var basex=w/2-imgWidth*imgNum/2; var n=pend.length; for(var i=0;i<n;i++){ pend[i].moveTo(point(basex+imgWidth*i,0)); } } } }; })(window);
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