某乎的登录界面代码--JS

最新推荐文章于 2024-05-13 16:21:10 发布

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本文介绍了一种使用HTML5 Canvas实现的动态点线交互效果。通过生成多个移动的点，并根据点间的距离动态绘制不同透明度的连线，创造出美观且流畅的视觉效果。适用于网页背景装饰或其他需要类似效果的应用场景。

原地址 . http://www.qdfuns.com/notes/25573/c983d0def24ac412b22d53a9bec3ae89.html

<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<title>canvas</title>
	<style type="text/css">
		body{
			text-align: center;
			background: #F7FAFC;
			overflow: hidden;
			background: #fff;
			}
	</style>
</head>
<body>
	<canvas id="Mycanvas"></canvas>
	<script>
        //定义画布宽高和生成点的个数
        var WIDTH = window.innerWidth,
            HEIGHT = window.innerHeight,
            POINT = 35;
        var canvas = document.getElementById('Mycanvas');
        canvas.width = WIDTH,
            canvas.height = HEIGHT;
        var context = canvas.getContext('2d');
        context.strokeStyle = 'rgba(0,0,0,0.02)',
            context.strokeWidth = 1,
            context.fillStyle = 'rgba(0,0,0,0.05)';
        var circleArr = [];
        //线条：开始xy坐标，结束xy坐标，线条透明度
        function Line(x, y, _x, _y, o) {
            this.beginX = x,
                this.beginY = y,
                this.closeX = _x,
                this.closeY = _y,
                this.o = o;
        }
        //点：圆心xy坐标，半径，每帧移动xy的距离
        function Circle(x, y, r, moveX, moveY) {
            this.x = x,
                this.y = y,
                this.r = r,
                this.moveX = moveX,
                this.moveY = moveY;
        }
        //生成max和min之间的随机数
        function num(max, _min) {
            var min = arguments[1] || 0;
            return Math.floor(Math.random() * (max - min + 1) + min);
        }
        // 绘制原点
        function drawCricle(cxt, x, y, r, moveX, moveY) {
            var circle = new Circle(x, y, r, moveX, moveY)
            cxt.beginPath()
            cxt.arc(circle.x, circle.y, circle.r, 0, 2 * Math.PI)
            cxt.closePath()
            cxt.fill();
            return circle;
        }
        //绘制线条
        function drawLine(cxt, x, y, _x, _y, o) {
            var line = new Line(x, y, _x, _y, o)
            cxt.beginPath()
            cxt.strokeStyle = 'rgba(0,0,0,' + o + ')'
            cxt.moveTo(line.beginX, line.beginY)
            cxt.lineTo(line.closeX, line.closeY)
            cxt.closePath()
            cxt.stroke();
        }
        //初始化生成原点
        function init() {
            circleArr = [];
            for (var i = 0; i < POINT; i++) {
                circleArr.push(drawCricle(context, num(WIDTH), num(HEIGHT), num(15, 2), num(10, -10) / 40, num(10, -10) / 40));
            }
            draw();
        }
        //每帧绘制
        function draw() {
            context.clearRect(0, 0, canvas.width, canvas.height);
            for (var i = 0; i < POINT; i++) {
                drawCricle(context, circleArr[i].x, circleArr[i].y, circleArr[i].r);
            }
            for (var i = 0; i < POINT; i++) {
                for (var j = 0; j < POINT; j++) {
                    if (i + j < POINT) {
                        var A = Math.abs(circleArr[i + j].x - circleArr[i].x),
                            B = Math.abs(circleArr[i + j].y - circleArr[i].y);
                        var lineLength = Math.sqrt(A * A + B * B);
                        var C = 1 / lineLength * 7 - 0.009;
                        var lineOpacity = C > 0.03 ? 0.03 : C;
                        if (lineOpacity > 0) {
                            drawLine(context, circleArr[i].x, circleArr[i].y, circleArr[i + j].x, circleArr[i + j].y, lineOpacity);
                        }
                    }
                }
            }
        }
        //调用执行
        window.onload = function () {
            init();
            setInterval(function () {
                for (var i = 0; i < POINT; i++) {
                    var cir = circleArr[i];
                    cir.x += cir.moveX;
                    cir.y += cir.moveY;
                    if (cir.x > WIDTH) cir.x = 0;
                    else if (cir.x < 0) cir.x = WIDTH;
                    if (cir.y > HEIGHT) cir.y = 0;
                    else if (cir.y < 0) cir.y = HEIGHT;
                }
                draw();
            }, 16);
        }
    </script>
</body>
</html>