【Canvas与色彩】多彩直线正三角形

【成图】
【代码】
<!DOCTYPE html>
<html lang="utf-8">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<head>
     <title>多彩直线正三角形 Draft3</title>
     <style type="text/css">
     .centerlize{
        margin:0 auto;
        width:1200px;
     }
     </style>
     </head>

     <body onload="init();">
        <div class="centerlize">
            <canvas id="myCanvas" width="12px" height="12px" style="border:1px dotted black;">
                如果看到这段文字说您的浏览器尚不支持HTML5 Canvas，请更换浏览器再试.
            </canvas>
        </div>
     </body>
</html>
<script type="text/javascript">
<!--
/*****************************************************************
* 将全体代码(从<!DOCTYPE到script>)拷贝下来，粘贴到文本编辑器中，
* 另存为.html文件，再用chrome浏览器打开，就能看到实现效果。
******************************************************************/

// canvas的绘图环境
var ctx;

// 高宽
const WIDTH=512;
const HEIGHT=512;

// 舞台对象
var stage;

//-------------------------------
// 初始化
//-------------------------------
function init(){
    // 获得canvas对象
    var canvas=document.getElementById('myCanvas');  
    canvas.width=WIDTH;
    canvas.height=HEIGHT;

    // 初始化canvas的绘图环境
    ctx=canvas.getContext('2d');  
    ctx.translate(WIDTH/2,HEIGHT/2);// 原点平移

    // 准备
    stage=new Stage();    
    stage.init();

    // 开幕
    animate();
}

// 播放动画
function animate(){    
    stage.update();    
    stage.paintBg(ctx);
    stage.paintFg(ctx);     

    // 循环
    if(true){
        //sleep(100);
        window.requestAnimationFrame(animate);   
    }
}

// 舞台类
function Stage(){
    // 初始化
    this.init=function(){
        
    }

    // 更新
    this.update=function(){    
        
    }

    // 画背景
    this.paintBg=function(ctx){
        ctx.clearRect(-WIDTH/2,-HEIGHT/2,WIDTH,HEIGHT);// 清屏    
    }

    // 画前景
    this.paintFg=function(ctx){
        // 底色
        ctx.save();
        ctx.fillStyle = "black";
        ctx.fillRect(-WIDTH/2,-HEIGHT/2,WIDTH,HEIGHT);
        ctx.restore();
        
        const R=210;//基准尺寸

        // #1
        ctx.save();
        var r=R*1.00;
        var rIn=r*0.25;
        var rOut=r*1.00;
        var N=3;

        var colors=["rgb(255,241,4)","rgb(254,209,4)","rgb(252,179,24)","rgb(247,148,31)",
                "rgb(244,118,34)","rgb(241,85,36)","rgb(237,30,36)","rgb(237,22,90)",
                "rgb(236,2,140)","rgb(203,19,142)","rgb(176,34,142)","rgb(148,41,145)",
                "rgb(88,48,145)","rgb(47,51,148)","rgb(4,95,174)","rgb(0,134,205)",
                "rgb(0,173,239)","rgb(1,170,184)","rgb(0,167,132)","rgb(0,167,82)",];

        for(var i=0;i<N;i++){
            var theta=Math.PI*2/N*i+Math.PI/6;
            var a=createPt(rOut*Math.cos(theta),rOut*Math.sin(theta)+rOut/4);
            var c=createPt(rOut*Math.cos(theta+Math.PI*2/3),rOut*Math.sin(theta+Math.PI*2/3)+rOut/4);

            var alpha=Math.asin(rIn/2/rOut);
            var beta=Math.PI*5/6-alpha;
            var b=createPt(rIn*Math.cos(theta+beta),rIn*Math.sin(theta+beta)+rOut/4);

            for(var j=0;j<=6;j++){
                var d=createPt(b.x+(c.x-b.x)/6*j,b.y+(c.y-b.y)/6*j);
                var lamda=0.97;
                var e=createPt(d.x*lamda+a.x*(1-lamda),d.y*lamda+a.y*(1-lamda));

                ctx.lineWidth=R/210*4;
                ctx.strokeStyle=colors[i*6+j];
                ctx.lineCap="round";
                ctx.beginPath();
                ctx.moveTo(a.x,a.y);
                ctx.lineTo(e.x,e.y);
                ctx.stroke();
            }
        }
        
        ctx.restore();
        
                    
        writeText(ctx,WIDTH/2-30,HEIGHT/2-5,"逆火制图","8px consolas","lightgrey");// 版权
    }
}

/*----------------------------------------------------------
函数:用于绘制实心圆
ctx:绘图上下文
x:矩形中心横坐标
y:矩形中心纵坐标
r:圆半径
style:填充圆的方案
----------------------------------------------------------*/
function drawSolidCircle(ctx,x,y,r,style){
    ctx.fillStyle=style;
    ctx.beginPath();
    ctx.arc(x,y,r,0,Math.PI*2,false);
    ctx.closePath();
    ctx.fill();
}

/*----------------------------------------------------------
函数:创建一个二维坐标点
x:横坐标
y:纵坐标
Pt即Point
----------------------------------------------------------*/
function createPt(x,y){
    var retval={};
    retval.x=x;
    retval.y=y;
    return retval;
}

/*----------------------------------------------------------
函数:延时若干毫秒
milliseconds:毫秒数
----------------------------------------------------------*/
function sleep(milliSeconds) {
    const date = Date.now();
    let currDate = null;
    while (currDate - date < milliSeconds) {
        currDate = Date.now();
    } 
}

/*----------------------------------------------------------
函数:书写文字
ctx:绘图上下文
x:横坐标
y:纵坐标
text:文字
font:字体
color:颜色
----------------------------------------------------------*/
function writeText(ctx,x,y,text,font,color){
    ctx.save();
    ctx.textBaseline="bottom";
    ctx.textAlign="center";
    ctx.font = font;
    ctx.fillStyle=color;
    ctx.fillText(text,x,y);
    ctx.restore();
}

/*-------------------------------------------------------------
To be whoever you want to be,
There's no time limit,
Start whenever you want,
You can change or stay the same,
And I hope you make the best of it,
I hope you see things that startle you,
I hope you live a life you're proud of,
And if you find that you're not
I hope you have the strength to start all over again.

放不下的，试着看开；
得不到的，学会释然；
过不去的，交给时间。
--------------------------------------------------------------*/
//-->
</script>
END
posted @ 2017-12-29 15:09 逆火狂飙阅读(1048) 评论(0) 收藏举报
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