Detailed explanation of random movement and collision examples of 10 balls using javascript

Home

Web Front-end

JS Tutorial

Detailed explanation of random movement and collision examples of 10 balls using javascript_javascript skills

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

May 16, 2016 pm 03:51 PM

javascript

The example in this article describes the method of realizing random movement and collision of 10 balls in JavaScript. Share it with everyone for your reference. The details are as follows:

I have been learning JavaScript for a while and have done some small cases. The most difficult one at present is the random collision effect of 10 small balls. I will post it and share it with you. I believe there are many like me. Rookies will have a lot of confusion when they start programming. I hope it can help some people.

Effect requirements: 10 small balls move randomly on the page, and they will bounce when they hit the window border or other small balls

Things:

1. 10 balls are 10 divs;
2. When the ball hits the window and bounces, define vx vy as the movement variable of the ball, and an elastic variable bounce (negative value). When the ball hits the window boundary, vx vy is multiplied by the bounce respectively, which changes the movement direction of the ball
3. The small balls collide and rebound. To put it simply, when the center distance variable dist of the two small balls is less than its minimum value (the sum of the radii), the moving direction of the ball is changed to achieve rebound

Okay, the code is as follows:

html and js are separate files

The test.html file is as follows:

<html>
 <head>
  <title></title>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   <style type="text/css">
body {
    margin:0;
    padding:0;
    text-align: center;
}
#screen { width: 800px; height: 640px; position: relative; background: #ccccff;margin: 0 auto;vertical-align: bottom}
#inner { position: absolute; left:0px; top:0px; width:100%; height:100%; }
#screen p {color:white;font:bold 14px;}
.one { background-image:url('bubble.png'); background-position: -66px -58px; }
.two { background-image:url('bubble.png'); background-position: -66px -126px;}
.three { background-image:url('bubble.png'); background-position: -66px -194px; }
.four { background-image:url('bubble.png'); background-position: -66px -263px; }
.five { background-image:url('bubble.png'); background-position: -66px -331px; }
.six { background-image:url('bubble.png'); background-position: -66px -399px; }
.seven { background-image:url('bubble.png'); background-position: -66px -194px; }
.eight { background-image:url('bubble.png'); background-position: -66px -263px; }
.nine { background-image:url('bubble.png'); background-position: -66px -331px; }
.ten{ background-image:url('bubble.png'); background-position: -66px -399px; }
  </style>
 </head>
 <body>
   <div id="screen" >
     <p>hi test it!</p>
     <div id="inner"></div>
   </div>
   <input type="button" id="start" value="start" >
   <input type="button" id="stop" value="stop">
   <br><br><br>
<script type="text/javascript" src="test.js"></script>
 </body>
</html>

The test.js file is as follows:

var getFlag=function (id) {
     return document.getElementByIdx_x(id);  //获取元素引用
}
var extend=function(des, src) {
     for (p in src) {
       des[p]=src[p];
   }
  return des;
 }
var clss=['one','two','three','four','five','six','seven','eight','nine','ten'];
var Ball=function (diameter,classn) {
  var ball=document.createElement_x("div");
  ball.className=classn;
  with(ball.style) {
    width=height=diameter+'px';position='absolute';
  }
  return ball;
}
var Screen=function (cid,config) {
  //先创建类的属性
  var self=this;
  if (!(self instanceof Screen)) {
    return new Screen(cid,config)
  }
  config=extend(Screen.Config, config)  //configj是extend类的实例
  self.container=getFlag(cid);      //窗口对象
  self.ballsnum=config.ballsnum;
  self.diameter=56;            //球的直径
  self.radius=self.diameter/2;
  self.spring=config.spring;       //球相碰后的反弹力
  self.bounce=config.bounce;       //球碰到窗口边界后的反弹力
  self.gravity=config.gravity;      //球的重力
  self.balls=[];             //把创建的球置于该数组变量
  self.timer=null;            //调用函数产生的时间id
  self.L_bound=0;            //container的边界
  self.R_bound=self.container.clientWidth;
  self.T_bound=0;
  self.B_bound=self.container.clientHeight;
};
Screen.Config={             //为属性赋初值
  ballsnum:10,
  spring:0.8,
  bounce:-0.9,
  gravity:0.05
};
Screen.prototype={
  initialize:function () {
    var self=this;
    self.createBalls();
    self.timer=setInterval(function (){self.hitBalls()}, 30)
  },
  createBalls:function () {
    var self=this, num=self.ballsnum;
    var frag=document.createDocumentFragment();  //创建文档碎片，避免多次刷新    
     for (i=0;i<num;i++) {
      var ball=new Ball(self.diameter,clss[ Math.floor(Math.random()* num )]);
      ball.diameter=self.diameter;
      ball.radius=self.radius;
      ball.style.left=(Math.random()*self.R_bound)+'px'; //球的初始位置，
      ball.style.top=(Math.random()*self.B_bound)+'px';
      ball.vx=Math.random() * 6 -3;
      ball.vy=Math.random() * 6 -3;
      frag.appendChild(ball);
      self.balls[i]=ball;
    }
    self.container.appendChild(frag);
  },
  hitBalls:function () {
    var self=this, num=self.ballsnum,balls=self.balls;
    for (i=0;i<num-1;i++) {
      var ball1=self.balls[i];
      ball1.x=ball1.offsetLeft+ball1.radius;   //小球圆心坐标
      ball1.y=ball1.offsetTop+ball1.radius;
      for (j=i+1;j<num;j++) {
        var ball2=self.balls[j];
        ball2.x=ball2.offsetLeft+ball2.radius;
        ball2.y=ball2.offsetTop+ball2.radius;
        dx=ball2.x-ball1.x;           //两小球圆心距对应的两条直角边
        dy=ball2.y-ball1.y;
        var dist=Math.sqrt(dx*dx + dy*dy);    //两直角边求圆心距
        var misDist=ball1.radius+ball2.radius;  //圆心距最小值
       if(dist < misDist) {          
          //假设碰撞后球会按原方向继续做一定的运动，将其定义为运动A  
          var angle=Math.atan2(dy,dx);
         //当刚好相碰，即dist=misDist时，tx=ballb.x, ty=ballb.y
          tx=balla.x+Math.cos(angle) * misDist; 
            ty=balla.y+Math.sin(angle) * misDist;
         //产生运动A后，tx > ballb.x, ty > ballb.y,所以用ax、ay记录的是运动A的值
            ax=(tx-ballb.x) * self.spring; 
            ay=(ty-ballb.y) * self.spring;
         //一个球减去ax、ay，另一个加上它，则实现反弹
            balla.vx-=ax;             
            balla.vy-=ay;
            ballb.vx+=ax;
            ballb.vy+=ay;
          }
      }
    }
    for (i=0;i<num;i++) {
      self.moveBalls(balls[i]);
    }
  },
  moveBalls:function (ball) {
    var self=this;
    ball.vy+=self.gravity;
    ball.style.left=(ball.offsetLeft+ball.vx)+'px';
    ball.style.top=(ball.offsetTop+ball.vy)+'px';
    //判断球与窗口边界相碰，把变量名简化一下
    var L=self.L_bound, R=self.R_bound, T=self.T_bound, B=self.B_bound, BC=self.bounce; 
    if (ball.offsetLeft < L) {
      ball.style.left=L;
      ball.vx*=BC;
    }
    else if (ball.offsetLeft + ball.diameter > R) {
      ball.style.left=(R-ball.diameter)+'px';
      ball.vx*=BC;
    }
    else if (ball.offsetTop < T) {
      ball.style.top=T;
      ball.vy*=BC;
    }
    if (ball.offsetTop + ball.diameter > B) {
      ball.style.top=(B-ball.diameter)+'px';
      ball.vy*=BC;
    }
  }
}
window.onload=function() {
  var sc=null;
  getFlag('start').onclick=function () {
    document.getElementByIdx_x("inner").innerHTML='';
    sc=new Screen('inner',{ballsnum:10, spring:0.8, bounce:-0.9, gravity:0.05});
    sc.initialize();
  }
  getFlag('stop').onclick=function() {
    clearInterval(sc.timer);
  }
}

The results after testing are still very good. You may think the code is quite long, but the idea is still quite clear:
First create the Screen class, and provide various attribute variables required for ball movement and collision in the Screen constructor, such as ballsnum, spring, bounce, gravity, etc.
Then use the prototype to give the corresponding functions, such as creating balls, createBalls, ball collision hitBalls, ball movement moveBalls, and adding corresponding functions to each function,
Finally the function is called with the button click event and that's it.

I hope this article will be helpful to everyone’s JavaScript programming design.

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

es6数组怎么去掉重复并且重新排序May 05, 2022 pm 07:08 PM

去掉重复并排序的方法：1、使用“Array.from(new Set(arr))”或者“[…new Set(arr)]”语句，去掉数组中的重复元素，返回去重后的新数组；2、利用sort()对去重数组进行排序，语法“去重数组.sort()”。

JavaScript的Symbol类型、隐藏属性及全局注册表详解Jun 02, 2022 am 11:50 AM

本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于Symbol类型、隐藏属性及全局注册表的相关问题，包括了Symbol类型的描述、Symbol不会隐式转字符串等问题，下面一起来看一下，希望对大家有帮助。

原来利用纯CSS也能实现文字轮播与图片轮播！Jun 10, 2022 pm 01:00 PM

怎么制作文字轮播与图片轮播？大家第一想到的是不是利用js，其实利用纯CSS也能实现文字轮播与图片轮播，下面来看看实现方法，希望对大家有所帮助！

JavaScript对象的构造函数和new操作符（实例详解）May 10, 2022 pm 06:16 PM

本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于对象的构造函数和new操作符，构造函数是所有对象的成员方法中，最早被调用的那个，下面一起来看一下吧，希望对大家有帮助。

JavaScript面向对象详细解析之属性描述符May 27, 2022 pm 05:29 PM

本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于面向对象的相关问题，包括了属性描述符、数据描述符、存取描述符等等内容，下面一起来看一下，希望对大家有帮助。

javascript怎么移除元素点击事件Apr 11, 2022 pm 04:51 PM

方法：1、利用“点击元素对象.unbind("click");”方法，该方法可以移除被选元素的事件处理程序；2、利用“点击元素对象.off("click");”方法，该方法可以移除通过on()方法添加的事件处理程序。

整理总结JavaScript常见的BOM操作Jun 01, 2022 am 11:43 AM

本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于BOM操作的相关问题，包括了window对象的常见事件、JavaScript执行机制等等相关内容，下面一起来看一下，希望对大家有帮助。

foreach是es6里的吗May 05, 2022 pm 05:59 PM

foreach不是es6的方法。foreach是es3中一个遍历数组的方法，可以调用数组的每个元素，并将元素传给回调函数进行处理，语法“array.forEach(function(当前元素,索引,数组){...})”；该方法不处理空数组。

See all articles

Hot AI Tools

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress images for free

Clothoff.io

AI clothes remover

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)

2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hello Kitty Island Adventure: How To Get Giant Seeds

1 months agoBy尊渡假赌尊渡假赌尊渡假赌

How Long Does It Take To Beat Split Fiction?

4 weeks agoByDDD

R.E.P.O. Save File Location: Where Is It & How to Protect It?

4 weeks agoByDDD

Two Point Museum: All Exhibits And Where To Find Them

1 months agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Notepad++7.3.1

Easy-to-use and free code editor

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software