雨滴碰撞效果"/>
Canvas绘制简易雨滴碰撞效果
实现会动的图形，向下播放多张静态的图片。一秒内要大于屏幕刷新的帧数(60) 也就是每隔1/60s执行一次函数在每次绘制的正方形上添加一个背景色为白色蒙板。
效果图
源代码
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><title>Canvas雨滴效果</title><style>body {margin: 0;}.rain {display: block;background-color: #000;}</style>
</head><body><canvas class="rain"></canvas><script>// 1.获取canvas并设置大小var canvas = document.querySelector('.rain');var ctxWidth, ctxHeight; // 定义画布的宽高~~function setResize() { // 根据浏览器窗口的改变，实时改变canvas画布的宽高，和浏览器保持一致window.onresize = arguments.callee;ctxWidth = window.innerWidth;ctxHeight = window.innerHeight;canvas.width = ctxWidth;canvas.height = ctxHeight;}();var ctx = canvas.getContext('2d');// 2.绘制单个会动的雨滴，根据单个雨滴进行接下来的雨滴对象Rain处理/* var y = 10;setInterval(function () {// 添加雨滴蒙版，使用透明色，使雨滴向上看起来有逐渐透明的效果ctx.fillStyle = 'rgba(0,0,0,0.05)';ctx.fillRect(0, 0, ctxWidth, ctxHeight);//绘制雨滴小矩形ctx.fillStyle = 'blue';ctx.fillRect(10, y++, 4, 10);}, 1000 / 60); */function random(min, max) { // 生成从min到max之间的随机数return Math.random() * (max - min) + min;}// 3.设置雨滴对象function Rain() { };Rain.prototype = {init: function () {this.x = random(0, ctxWidth);this.y = 0;this.vY = random(4, 5); // 雨滴在Y轴上运动的速度this.h = random(0.8 * ctxHeight, 0.9 * ctxHeight); // 雨滴停止的Y轴位置，整个画布的80%-90%高度的地方this.r = 1; // 圆形半径this.vR = 1; // 圆形半径变化的速度},draw: function () {if (this.y <= this.h) {//绘制雨滴小矩形ctx.beginPath();ctx.fillStyle = '#31f7f7';ctx.fillRect(this.x, this.y, 4, 10);} else {ctx.beginPath();ctx.strokeStyle = '#31f7f7';ctx.arc(this.x, this.y, this.r, 0, Math.PI * 2);ctx.stroke();}},move: function () {if (this.y <= this.h) {this.y += this.vY;} else {if (this.r <= 100) {this.r += this.vR;}else {this.init();}}this.draw();}}// 创建多个雨滴的函数，将雨滴push进入arrRains中var arrRains = [];function createRain(num) {// 每200ms生成一滴雨滴for (var i = 0; i <= num; i++) {setTimeout(function () {var rain = new Rain();rain.init();rain.draw();arrRains.push(rain);}, 200 * i);}}createRain(50);setInterval(function () {// 添加雨滴蒙版，使用透明色，使雨滴向上看起来有逐渐透明的效果ctx.fillStyle = 'rgba(0,0,0,0.05)';ctx.fillRect(0, 0, ctxWidth, ctxHeight);for (item of arrRains) {item.move();}}, 1000 / 60); // 每1/60秒执行一次函数</script>
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Canvas绘制简易雨滴碰撞效果
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