JS+canvas画布实现炫酷的旋转星空效果示例

这篇文章主要介绍了JS+canvas画布实现炫酷的旋转星空效果,结合实例形式分析了js结合HTML5 canvas图形绘制与数值计算相关操作技巧,需要的朋友可以参考下

本文实例讲述了JS+canvas画布实现炫酷的旋转星空效果。分享给大家供大家参考，具体如下：

canvas是html5的新标签，其画布功能尤为强大。当然了canvas在IE10以下浏览器是不兼容的，所以呢为了特效肯定是牺牲一定的兼容性。这里呢，分享一个基于canvas开发的浩瀚星河插件，其实这个源代码是网上下载的，我把它整合了一下，重新封装一些参数提供更多的可改项。

首先引入两个javascript脚本，一个是jquery插件，另一个是封装好的cosmos_canvas.js

HTML，当然如果浏览器不支持canvas的话，运行程序没效果，并显示“该浏览器不支持canvas”

cosmos_canvas.js脚本

 function canvas(id,starscolor,starsamount,starsradius,movrange,speed,trailing){ //宇宙特效 "use strict"; var canvas = document.getElementById(id), ctx = canvas.getContext('2d'), w = canvas.width = window.innerWidth, h = canvas.height = window.innerHeight, hue = starscolor,//230 stars = [], count = 0, maxStars = starsamount;//星星数量 var canvas2 = document.createElement('canvas'), ctx2 = canvas2.getContext('2d'); canvas2.width = 100; canvas2.height = 100; var half = canvas2.width / 2, gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half); gradient2.addColorStop(0.025, '#CCC'); gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)'); gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)'); gradient2.addColorStop(1, 'transparent'); ctx2.fillStyle = gradient2; ctx2.beginPath(); ctx2.arc(half, half, half, 0, Math.PI * 2); ctx2.fill(); // End cache function random(min, max) { if (arguments.length <2) { max = min; min = 0; } if (min > max) { var hold = max; max = min; min = hold; } return Math.floor(Math.random() * (max - min + 1)) + min; } function maxOrbit(x, y) { var max = Math.max(x, y), diameter = Math.round(Math.sqrt(max * max + max * max)); return diameter / movrange; //星星移动范围，值越大范围越小， } var Star = function() { this.orbitRadius = random(maxOrbit(w, h)); this.radius = random(starsradius, this.orbitRadius) / 8; //星星半径大小 this.orbitX = w / 2; this.orbitY = h / 2; this.timePassed = random(0, maxStars); this.speed = random(this.orbitRadius) / speed; //星星移动速度 this.alpha = random(2, 10) / 10; count++; stars[count] = this; } Star.prototype.draw = function() { var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX, y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY, twinkle = random(10); if (twinkle === 1 && this.alpha > 0) { this.alpha -= 0.05; } else if (twinkle === 2 && this.alpha <1) { this.alpha += 0.05; } ctx.globalAlpha = this.alpha; ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius); this.timePassed += this.speed; } for (var i = 0; i

调用方法：这里没写任何样式所以默认情况下是全屏效果

 $(function(){ //canvas的id名，星星颜色(hsla的hue色调)，星星数量，星星半径比，星星移动范围(值越大范围越小)，星星移动速度(值越大速度越慢),星星拖尾效果(0~1值越小拖尾越明显) canvas("starts",230,1000,60,2,50000,0.5); });

效果：

然后我再加3个canvas，改些参数做效果对比吧

HTML

javascript

 $(function(){ //canvas的id名，星星颜色(hsla的hue色调)，星星数量，星星半径比，星星移动范围(值越大范围越小)，星星移动速度(值越大速度越慢),星星拖尾效果(0~1值越小拖尾越明显) canvas("starts",230,1000,60,2,50000,0.5); canvas("starts1",160,800,70,2.5,55000,0.4); canvas("starts2",80,600,80,3,60000,0.3); canvas("starts3",0,400,90,3.5,65000,0.2); $("canvas").width($(window).width()/2); $("canvas").height($(window).height()/2); $("canvas").css("float","left"); });

就这样，四个浩瀚的宇宙出来了