Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

JavaScript

Babel is required to process package imports. If you need a different preprocessor remove all packages first.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Behavior

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                <canvas id=canvas></canvas>
              
            
!

CSS

              
                * {
	margin: 0;
	padding: 0;
}

html {
	overflow: hidden;
}

canvas {
	cursor: none;
}
              
            
!

JS

              
                window.onload = function() {

	var canvas = document.getElementById("canvas");
	var ctx = canvas.getContext("2d");

	var pi = Math.PI;

	var centerX, centerY;
	var part_num = 2000; //粒子数量

	var mousedown = false;
	var X, Y; //鼠标坐标

	var P = [];
	var part = function(x, y, vx, vy, r, red, green, blue, alpha, col) {
		this.x = x;
		this.y = y;
		this.vx = vx; //初始向左移动
		this.vy = vy; //初始向右移动
		this.r = r; //大小
		this.red = red;
		this.green = green;
		this.blue = blue;
		this.alpha = alpha;
		this.col = col;
	};

	window.onmousemove = function(e) {
		X = e.clientX;
		Y = e.clientY;
	}

	window.onmousedown = function() {
		mousedown = true;
	}

	window.onmouseup = function() {
		mousedown = false;
	}

	var mouseover = false;
	window.onmouseover = function() {
		mouseover = true;
	}

	window.onmouseout = function() {
		mouseover = false;
	}

	function rand(min, max) {
		return Math.random() * (max - min) + min;
	}

	function dist(dx, dy) {
		return Math.sqrt(dx * dx + dy * dy);
	}

	function size() {
		canvas.width = window.innerWidth;
		canvas.height = window.innerHeight;
		centerX = canvas.width / 2;
		centerY = canvas.height / 2;
	}

	size();
	X = centerX;
	Y = centerY;

	function init() {
		var x, y, vx, vy, r, red, green, blue, alpha, col;
		for (var i = 0; i < part_num; i++) {
			x = rand(0, canvas.width);
			y = rand(0, canvas.height);
			vx = rand(-5, 5);
			vy = rand(-5, 5);
			r = rand(1, 10);
			red = Math.round(rand(150, 200));
			green = Math.round(rand(100, 255));
			blue = Math.round(rand(180, 255));
			alpha = 1;
			col = "rgba(" + red + "," + green + "," + blue + "," + alpha + ")";

			P.push(new part(x, y, vx, vy, r, red, green, blue, alpha, col));
		}
	}
	// 背景绘制
	function bg() {
		// 使用 fillStyle 属性来设置用于填充绘图的颜色
		ctx.fillStyle = "raba(25,25,30,1)";
		// 使用fillRect() 方法绘制“已填色”的矩形
		ctx.fillRect(0, 0, canvas.width, canvas.height);
		//clearRect() 方法清空给定矩形内的指定像素
		// ctx.clearRect(0, 0, canvas.width, canvas.height);
	}

	//鼠标吸引
	function attract(p) {
		var dx = (p.x - X),
			dy = (p.y - Y),
			dist = Math.sqrt(dx * dx + dy * dy), //返回距离(平方根)
			angle = Math.atan2(dy, dx); //返回坐标(dx,dy)与 X轴之间的角度的弧度

		if (dist > 50 && dist < 500) {
			if (!mousedown) {
				p.vx -= (200 / (p.r * dist)) * Math.cos(angle);
				p.vy -= (200 / (p.r * dist)) * Math.sin(angle);
			} else if (mousedown) {
				p.vx += (300 / (p.r * dist)) * Math.cos(angle);
				p.vy += (300 / (p.r * dist)) * Math.sin(angle);
			}
		}
	}

	//粒子弹弹弹
	function bounce(b) {
		if (b.x < b.r) {
			b.x = b.y;
			b.vx *= -3;
		}
		if (b.x > canvas.width - b.r) {
			b.x = canvas.width - b.r;
			b.vx *= -3;
		}

		if (b.y - b.r < 0) {
			b.y = b.r;
			b.vy *= -3;
		}
		if (b.y > canvas.height - b.r) {
			b.y = canvas.height - b.r;
			b.vy *= -3;
		}
	}

	// 鼠标拖动
	function draw() {
		var p;
		for (var i = 0; i < P.length; i++) {
			p = P[i];

			if (mouseover) attract(p);
			bounce(p);

			p.x += p.vx;
			p.y += p.vy;

			p.vx *= .975;
			p.vy *= .975;

			ctx.fillStyle = p.col;
			ctx.fillRect(p.x, p.y, p.r, p.r);
		}
		ctx.strokeStyle = (!mousedown) ? "rgba(0,0,0,,1)" : "rgba(255,0,0,1)";

		ctx.beginPath();
		ctx.moveTo(X, Y - 10);
		ctx.lineTo(X, Y + 10);
		ctx.moveTo(X - 10, Y);
		ctx.lineTo(X + 10, Y);
		ctx.stroke();
	}

	function loop() {
		bg();
		draw();
		window.requestAnimationFrame(loop);
	}
	// 事件
	window.onresize = size;

	// 初始化
	init();
	loop();

}
              
            
!
999px

Console