js实现的牛顿摆效果

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=
;
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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