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js判断向量叉点 并求出交点坐标

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08/07
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 代码如下可以直接运行，判断向量相交并求出交点坐标

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>判断线段相交并求交点</title>
<style>
.title{text-align:center;}
.wrapper{width: 500px;height: 500px;margin: 0 auto;border: 1px solid #000000;}
.content{position: relative;height: 500px;}
.dot{position: absolute;width:1px;height: 1px;overflow: hidden;font-size:0;line-height: 0; background: #333;} </style>
</head>
<body>
<h1 class="title">判断相交并求交点</h1>
<div class="wrapper">
<div class="content" id="content"></div></div>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js"></script>
<script>
//*********定义加载模块方法 start **************//
(function (window, undefined) {
if (window.define) {
return
}
function isFunction(obj) {
return Object.prototype.toString.call(obj) === "[object Function]"
} var MM = {};
var initModuleName = "initRun"; function require(name) {
if (!MM[name]) {
throw new Error("Module " + name + " is not defined.")
}
var module = MM[name];
if (module.inited === false) {
runModule(name)
}
return module.ret
} function runModule(name) {
var exports = {};
var module = MM[name];
if (isFunction(MM[name].factory)) {
var ret = MM[name].factory.apply(undefined, [require, exports, undefined]);
module.ret = ret === undefined ? exports : ret
} else {
module.ret = MM[name].factory
}
module.inited = true
} function define(name, deps, factory) {
if (MM[name]) {
throw new Error("Module " + name + " has been defined already.")
}
if (isFunction(deps)) {
factory = deps
}
MM[name] = {factory:factory, inited:false};
if (name === initModuleName) {
runModule(name)
}
} window.define = define
})(window);
//*********定义加载模块方法 end **************//
(function(){
/**
* 可以缓存的操作节点
*/
var $dom = {
content : $('#content')
}
define('Mode/drawLine',function(require){
var drawLine = function(){};
drawLine.prototype = {
/**
* @根据两坐标画线段
* @param vector1
* @param vector2
*/
draw : function(vector1 ,vector2){
var k = (vector2.y - vector1.y)/((vector2.x - vector1.x));//求斜率k
var y,x ;_lineHtml = [];//用来保存xy变量坐标
var maxX = Math.max(vector2.x,vector1.x),
minX = Math.min(vector2.x,vector1.x),
maxY = Math.max(vector2.y,vector1.y),
minY = Math.min(vector2.y,vector1.y); //利用长度相隔比较大的作为循环确保画的线段质量高些
if((maxX-minX) > (maxY - minY) || (maxX-minX) == (maxY - minY)){
for(var i = minX;i<maxX;i++){
y = k * (i - vector1.x) + vector1.y;
_lineHtml.push('<div class="dot" style="left:'+ i +'px;top:'+ y +'px"></div>'); } }else{
for(var i = minY;i<maxY;i++){
x = (i - vector1.y)/k + vector1.y;
_lineHtml.push('<div class="dot" style="left:'+ x +'px;top:'+ i +'px"></div>'); } } $dom.content.append(_lineHtml.join('')) ; } ,
/**
* @desc求交点坐标具体算法见http://www.cnblogs.com/rubyxie/articles/3548450.html
* @param vector1
* @param vector2
* @param vector3
* @param vector4
* @return {Object}交点坐标
*/
computeCrossVector : function (vector1 ,vector2,vector3 ,vector4){
var crossVector = {},
v1 = {"x" : vector2.x - vector1.x , "y" : vector2.y - vector1.y},
v2 = {"x" : vector4.x - vector3.x , "y" : vector4.y - vector3.y};
var product = v1.x * v2.y - v1.y * v2.x; //两向量的乘积
//计算二阶行列式的两个常数项
var const1 = vector1.x * v1.y - vector1.y * v1.x ;
const2 = vector3.x * v2.y - vector3.y * v2.x ; crossVector.x = (const2 * v1.x - const1 * v2.x)/product;
crossVector.y = (const2 * v1.y - const1 * v2.y)/product; return crossVector; }
,
//向量叉乘
crossMul: function (v1, v2) {
return v1.x * v2.y - v1.y * v2.x;
}
,
checkLineCross : function(vector1 ,vector2,vector3 ,vector4){ var v1 = {x: vector1.x - vector3.x, y: vector1.y - vector3.y},
v2 = {x: vector2.x - vector3.x, y: vector2.y - vector3.y},
v3 = {x: vector4.x - vector3.x, y: vector4.y - vector3.y},
v = this.crossMul(v1, v3) * this.crossMul(v2, v3),
v1 = {x: vector3.x - vector1.x, y: vector3.y - vector1.y},
v2 = {x: vector4.x - vector1.x, y: vector4.y - vector1.y},
v3 = {x: vector2.x - vector1.x, y: vector2.y - vector1.y}; return (v <= 0 && this.crossMul(v1, v3) * this.crossMul(v2, v3) <= 0) ? true : false; } };
return drawLine; }); /**
* @desc 模块启动函数
*/
define('initRun',function(require){
var vector1 = {"x" :50 ,"y":100 }, //定义四个向量坐标
vector2 = {"x" :180 ,"y":400 },
vector3 = {"x" :10 ,"y":104 },
vector4 = {"x" :200 ,"y":104 }; var drawMode = require("Mode/drawLine");
var line = new drawMode; line.draw(vector1,vector2);
line.draw(vector3,vector4); if(line.checkLineCross(vector1,vector2,vector3,vector4)){
var cross = line.computeCrossVector(vector1,vector2,vector3,vector4);
$dom.content.append('<div>交点坐标为：x坐标为 '+ cross.x + ' y坐标 ：'+cross.y+'</div>'); }else{
alert("这两向量线段未相交");
}
}) })();
</script>
</body>
</html>