<!DOCTYPE html><html> ???<head> ????<title>水波背景</title> ????<meta charset="utf-8" /> ????<style> ????????html, body {width:100%; height:100%; padding:0; margin:0;} ????</style> ???</head> ???<body> ????????<canvas id="canvas" style="position:absolute;top:0px;left:0px;z-index:1;"></canvas> ???????<script type="text/javascript"> ??????????//获得canvas容器 ?????????var canvas = document.getElementById(‘canvas‘); ??????????//获得画笔 ?????????var ctx = canvas.getContext(‘2d‘); ??????????//canvas设置宽度 ?????????canvas.width = canvas.parentNode.offsetWidth; ??????????//canvas设置高度 ?????????canvas.height = canvas.parentNode.offsetHeight; ?????????//如果浏览器支持requestAnimFrame则使用requestAnimFrame否则使用setTimeout ??????????window.requestAnimFrame = (function(){ ??????????return window.requestAnimationFrame ?|| ????????????window.webkitRequestAnimationFrame || ????????????window.mozRequestAnimationFrame || ????????????function( callback ){ ?????????????????window.setTimeout(callback, 1000 / 60); ????????????}; ??????????})(); ??????????// 波浪大小 ?????????var boHeight = canvas.height / 10; ?????????var posHeight = canvas.height / 1.2; ?????????//初始角度为0 ??????????var step = 0; ??????????//定义三条不同波浪的颜色 ??????????var lines = ["rgba(0,222,255, 0.2)", "rgba(157,192,249, 0.2)", "rgba(0,168,255, 0.2)"]; ??????????function loop(){ ??????????????//清除canvas内容 ??????????????ctx.clearRect(0,0,canvas.width,canvas.height); ???????????????step++; ???????????????//画3个不同颜色的矩形 ???????????????for(var j = lines.length - 1; j >= 0; j--) { ????????????????ctx.fillStyle = lines[j]; ????????????????//每个矩形的角度都不同，每个之间相差45度 ????????????????var angle = (step+j*50)*Math.PI/180; ????????????????var deltaHeight = Math.sin(angle) * boHeight; ???????????????var deltaHeightRight = Math.cos(angle) * boHeight; ????????????????ctx.beginPath(); ???????????????ctx.moveTo(0, posHeight+deltaHeight); ????????????????ctx.bezierCurveTo(canvas.width/2, posHeight+deltaHeight-boHeight, canvas.width / 2, posHeight+deltaHeightRight-boHeight, canvas.width, posHeight+deltaHeightRight); ????????????????ctx.lineTo(canvas.width, canvas.height); ????????????????ctx.lineTo(0, canvas.height); ????????????????ctx.lineTo(0, posHeight+deltaHeight); ????????????????ctx.closePath(); ????????????????ctx.fill(); ???????????} ??????????requestAnimFrame(loop); ?????????} ??????????loop(); ?????</script></body></html>js实现水波纹背景
原文地址：http://www.cnblogs.com/wanf/p/7808505.html