html5 canvas星空粒子连线效果【转载】-静水博客

html5 canvas星空粒子连线效果【转载】

2018/08/29 标签： canvas星空连线

canvas粒子星空连线效果

<!DOCTYPE html>
<html>
 
<head>
    <meta charset="UTF-8">
    <title>离子星空</title>
    <style type="text/css">
        * {
            margin: 0;
            padding: 0;
        }
        #myCanvas {
            background-color: black;
        }
    </style>
</head>
 
<body>
    <canvas id="myCanvas"></canvas>
</body>
<script type="text/javascript">
    var canvas = document.getElementById("myCanvas");
    canvas.width = document.documentElement.clientWidth;
    canvas.height = document.documentElement.clientHeight;
    var ctx = canvas.getContext("2d");
    //创建小球的构造函数
    function Ball() {
        this.x = randomNum(3, canvas.width - 3);
        this.y = randomNum(3, canvas.height - 3);
        this.r = randomNum(1, 3);
        this.color = randomColor();
        this.speedX = randomNum(-3, 3) * 0.2;
        this.speedY = randomNum(-3, 3) * 0.2;
    }
    Ball.prototype = {
            //绘制小球
            draw: function () {
                    ctx.beginPath();
                    ctx.globalAlpha = 1;
                    ctx.fillStyle = this.color;
                    ctx.arc(this.x, this.y, this.r, 0, Math.PI * 2);
                    ctx.fill();
                },
                //小球移动
                move: function () {
                    this.x += this.speedX;
                    this.y += this.speedY;
                    //为了合理性,设置极限值
                    if (this.x <= 3 || this.x > canvas.width - 3) {
                        this.speedX *= -1;
                    }
                    if (this.y <= 3 || this.y >= canvas.height - 3) {
                        this.speedY *= -1;
                    }
                }
        }
        //存储所有的小球
    var balls = [];
    //创建200个小球
    for (var i = 0; i < 150; i++) {
        var ball = new Ball();
        balls.push(ball);
    }
    main();
 
    function main() {
            ctx.clearRect(0, 0, canvas.width, canvas.height);
            //鼠标移动绘制线				
            mouseLine();
            //小球与小球之间自动画线
            drawLine();
            //使用关键帧动画，不断的绘制和清除
            window.requestAnimationFrame(main);
        }
        //添加鼠标移动事件
        //记录鼠标移动时的mouseX坐标
    var mouseX;
    var mouseY;
    canvas.onmousemove = function (e) {
            var ev = event || e;
            mouseX = ev.offsetX;
            mouseY = ev.offsetY;
        }
        //判断是否划线
 
    function drawLine() {
            for (var i = 0; i < balls.length; i++) {
                balls[i].draw();
                balls[i].move();
                for (var j = 0; j < balls.length; j++) {
                    if (i != j) {
                        if (Math.sqrt(Math.pow((balls[i].x - balls[j].x), 2) + Math.pow((balls[i].y - balls[j].y), 2)) < 80) {
                            ctx.beginPath();
                            ctx.moveTo(balls[i].x, balls[i].y);
                            ctx.lineTo(balls[j].x, balls[j].y);
                            ctx.strokeStyle = "white";
                            ctx.globalAlpha = 0.2;
                            ctx.stroke();
                        }
                    }
                }
            }
        }
        //使用鼠标移动划线
 
    function mouseLine() {
            for (var i = 0; i < balls.length; i++) {
                if (Math.sqrt(Math.pow((balls[i].x - mouseX), 2) + Math.pow((balls[i].y - mouseY), 2)) < 80) {
                    ctx.beginPath();
                    ctx.moveTo(balls[i].x, balls[i].y);
                    ctx.lineTo(mouseX, mouseY);
                    ctx.strokeStyle = "white";
                    ctx.globalAlpha = 0.8;
                    ctx.stroke();
                }
            }
        }
        //随机函数
 
    function randomNum(m, n) {
            return Math.floor(Math.random() * (n - m + 1) + m);
        }
        //随机颜色
 
    function randomColor() {
        return "rgb(" + randomNum(0, 255) + "," + randomNum(0, 255) + "," + randomNum(0, 255) + ")";
    }
</script>
 
</html>

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