How to draw a tree with js code-JS Tutorial-php.cn

How to draw a tree with js code

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Release： 2018-04-14 15:44:17

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The content of this article is to share with you how to draw a tree using js code. It has a certain reference value. Friends in need can refer to it

Create a new HTML document in one step:

<html>  
 <head>   
 <style  type="text/css">   
 /*设置body样式*/      
 body{   
   overflow:hidden;     
   background: black; 
 }   
 </style>   
 </head>   
 <!--设置屏幕背景黑色-->   
 <body>     
    <script src="js.js"></script>   
 </body>
</html>

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The second step is to create a js document:

//创建画布
var mycanvas=document.createElement("canvas");
//设置树的宽度和高度
mycanvas.width=1500;
mycanvas.height=900;
//绘制画布的对象并设置为2D
var context=mycanvas.getContext("2d");
//设置划线的类型颜色
context.strokeStyle="#ff00ff";
//设置线的宽度
context.lineWidth=2;
//将画布添加到窗体上
document.body.appendChild(mycanvas);
///////////////////////////////////////////
/*---------------画图部分----------------*/
///////////////////////////////////////////
//画树深度
var n=10;
//设置初始角度
var th=-Math.PI/2;
//设置初始位置
var x0=700;
var y0=700;
//调用绘图函数
draw(n-1,700,700,100,th);
/*------------绘制树的函数-------------------*/
function draw(n,x0,y0,length,th){//（画树深度，起始位置x0,y0，长度，度数）
      if(n==0)
  return;
      //计算线条末端坐标
  var x1=x0+length*Math.cos(th);
  var y1=y0+length*Math.sin(th);
  //画线
      drawline(x0,y0,x1,y1);
  //画子树递归
  draw(n-1,x1,y1,0.8*length*(Math.random()+0.4),th+(20+Math.random()*5)*Math.PI/180);
  draw(n-1,x1,y1,0.6*length*(Math.random()+0.5),th-(30+Math.random()*5)*Math.PI/180);
}
/*--------------绘制线段-----------------------*/
function drawline(x0,y0,x1,y1){
context.moveTo(x0,y0);//设置绘制的起点
context.lineTo(x1,y1);//设置线段的末尾
context.stroke();     //绘制
}

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The final result is as shown below :

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