那些年我们一起看过的大风车！

2018-06-24 01:32:10来源：未知阅读 ()

　使用JS实现大风车！

　　下面附上效果图：

　　最后附上源码，复制即可用：

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>那年我们一起看过的大风车</title>
<style type="text/css">
#box{ 
    border:2px solid #f60; width:800px; height:600px; margin:0 auto;
}
</style>
<script type="text/javascript">
    var canvas,context;//画布、上下文
    var X,Y;//风车的圆心X坐标、Y坐标
    var canvasWidth,canvasHeight;//画布的宽高
    var speed = 1;//风车的转速、默认为1
    var R = 10;//风车的半径

    //初始化页面函数
    function init(){
        initCanvas();
        initParams();
        draw();
        setInterval(draw,20);
    }
    
    //初始化画布宽高、风车圆心坐标
    function initParams(){
        canvasWidth = canvas.width;
        canvasHeight = canvas.height;
        X = canvasWidth/2;
        Y = canvasHeight/4;
    }
   
    //设置风的大小
    function setSpeed(speed){
        this.speed = speed;
    }
   
    //设置风的大小
    function setR(R){
        this.R = R;
    }
    
    //初始化画布
    function initCanvas(){
        try{
        canvas = document.getElementById("windmill");
        context = canvas.getContext("2d");
        }catch(e){
            document.getElementById("tip_info").innerHTML = "您的浏览器不支持！";
        }
    }

    //绘制半圆
    function drawArc(tangle, style){
         context.beginPath();
         var trunkGradient = context.createLinearGradient(X, Y, X, Y+4*R);
         trunkGradient.addColorStop(0, style);
         trunkGradient.addColorStop(1, '#FFF00F');
         context.fillStyle = trunkGradient;
         
        context.arc(X - (2*R*Math.cos(tangle)), Y - 2*R*Math.sin(tangle), 2*R, tangle, Math.PI+tangle, true);
        context.closePath();
        context.fill();
        context.save();
    }

    //绘制手把柄
    function drawHandle(){
         var trunkGradient = context.createLinearGradient(X, Y, X+10, Y);
         trunkGradient.addColorStop(0, '#663300');
         trunkGradient.addColorStop(0.4, '#996600');
         trunkGradient.addColorStop(1, '#552200');
         context.fillStyle = trunkGradient;
         context.fillRect(X, Y, 0.2*R, 8*R);
    }

    //绘制文字
    function drawText(){
         context.font = "30px 宋体 bold";
         context.textAlign = 'center';
         context.fillText('那些年我们一起看过的大风车！', X, canvasWidth - 300, 300);
    }

    //绘制函数
    var tangle = 0;
    function draw(){
        tangle = tangle + (speed*1/32)*Math.PI;
        context.clearRect(0,0,canvasWidth,canvasHeight);
        drawHandle();
        drawText();
        drawArc(tangle,"#552200");
        drawArc(tangle+1/2*Math.PI, "#990000");
        drawArc(tangle+Math.PI, "#0033FF");
        drawArc(tangle+3/2*Math.PI, "#225500");
        document.getElementById("tip_info").innerHTML = "转动角度："+parseInt(tangle)+"    当前的风速："+speed;
    }
    window.addEventListener("load",init,true);
</script>
</head>
<body>
    <div id="box">
        <canvas id = "windmill" style = "background-color:#001111" width = "800px" height = "600px"></canvas>
        <div id = "tip_info"></div>
        <div>
            <button onClick="setSpeed(0)">停止</button>
            <button onClick="setSpeed(0.1)">微风</button>
            <button onClick="setSpeed(0.5)">小风</button>
            <button onClick="setSpeed(1)">中风</button>
            <button  onClick="setSpeed(2)">大风</button>
            <button  onClick="setSpeed(4)">狂风</button>
            |
            <button onClick="setR(5)">小号</button>
            <button onClick="setR(20)">中号</button>
            <button onClick="setR(30)">大号</button>
            <button onClick="setR(35)">超大号</button>
        </div>
    </div>
</body>
</html>