利用 canvas 画布实现网页酷炫星空背景
自从博客上了星空背景之后,经常有人问我星空背景是怎么实现,我只能说,我不会前端,也没有学过 css,js 等知识,代码是我从网上找的,搜索相关资料调试后加到网站里实现的。
本文最后更新于 2019-02-28【2249 天前】,文中所描述的信息可能已发生改变,请谨慎使用。如有问题或建议,欢迎在文章底部留言参与讨论!
自从博客上了星空背景之后,经常有人问我星空背景是怎么实现,我只能说,我不会前端,也没有学过 css,js 等知识,代码是我从网上找的,搜索相关资料调试后加到网站里实现的。
现在把我找到的代码分享给大家,至于如何加入到网站作为背景,还请大家不要做伸手党,我只能说 Handsome 主题需要开启透明背景
,其他的需要自己找找资料搜索下,很容易解决。。
canvas 是啥?
<canvas>
是一个可以使用脚本(通常为 JavaScript
)来绘制图形的 HTML 元素。例如,它可以用于绘制图表、制作图片构图或者制作简单的(以及不那么简单的)动画。<canvas>
最早由 Apple 引入 WebKit,用于 Mac OS X 的 Dashboard,随后被各个浏览器实现。如今,所有主流的浏览器都支持它。
上述资料来自:https://developer.mozilla.org/zh-CN/docs/Web/API/Canvas_API/Tutorial
特效与 Demo
见本站背景,或者单独的一个 Demo 页:https://www.imtqy.com/demo/xingkong/
代码与实现
引入画布
网页的 <body>
中引入 <canvas>
画布 :
<canvas id="canvas"></canvas>
画布内容渲染
利用 JavaScript 进行渲染:
<script>
"use strict";
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
w = canvas.width = window.innerWidth,
h = canvas.height = window.innerHeight,
hue = 217,
stars = [],
count = 0,
maxStars = 600;
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, '#fff');
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();
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 / 2;
}
var Star = function() {
this.orbitRadius = random(maxOrbit(w, h));
this.radius = random(60, this.orbitRadius) / 12;
this.orbitX = w / 2;
this.orbitY = h / 2;
this.timePassed = random(0, maxStars);
this.speed = random(this.orbitRadius) / 50000;
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 < maxStars; i++) {
new Star();
}
function animation() {
ctx.globalCompositeOperation = 'source-over';
ctx.globalAlpha = 0.8;
ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 1)';
ctx.fillRect(0, 0, w, h)
ctx.globalCompositeOperation = 'lighter';
for (var i = 1, l = stars.length; i < l; i++) {
stars[i].draw();
};
window.requestAnimationFrame(animation);
}
animation();
</script>
完整的 html 代码
[collapse title="有点长,不予显示,点击可查看" status="false"]
<html>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge, chrome=1">
<meta http-equiv="Cache-Control" content="no-transform"/>
<meta http-equiv="Cache-Control" content="no-siteapp"/>
<meta name="renderer" content="webkit">
<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no">
<title>利用 canvas 画布实现网页星空背景 - Quanyin 说</title>
<body>
<canvas id="canvas"></canvas>
<script>
"use strict";
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
w = canvas.width = window.innerWidth,
h = canvas.height = window.innerHeight,
hue = 217,
stars = [],
count = 0,
maxStars = 600;
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, '#fff');
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();
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 / 2;
}
var Star = function() {
this.orbitRadius = random(maxOrbit(w, h));
this.radius = random(60, this.orbitRadius) / 12;
this.orbitX = w / 2;
this.orbitY = h / 2;
this.timePassed = random(0, maxStars);
this.speed = random(this.orbitRadius) / 50000;
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 < maxStars; i++) {
new Star();
}
function animation() {
ctx.globalCompositeOperation = 'source-over';
ctx.globalAlpha = 0.8;
ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 1)';
ctx.fillRect(0, 0, w, h)
ctx.globalCompositeOperation = 'lighter';
for (var i = 1, l = stars.length; i < l; i++) {
stars[i].draw();
};
window.requestAnimationFrame(animation);
}
animation();
</script>
</body>
</html>
[/collapse]
代码下载
下载链接:https://www.lanzous.com/i2mt02f
源码来源:https://www.jq22.com/code69
本文作者:Quanyin Tang
本文链接:利用 canvas 画布实现网页酷炫星空背景 - https://www.imtqy.com/demo-canvas-xingkong.html
版权声明:如无特别声明,本文即为原创文章,仅代表个人观点,版权归 Quanyin 所有,未经允许禁止转载,经授权转载请注明出处!
本作品采用 知识共享署名-非商业性使用-相同方式共享 4.0 国际许可协议 进行许可。
想要复制
文章里不是提供了下载链接了么,直接下载demo就完事了
来看看大佬
博主可以说下怎么添加的么,不懂PHP啊。。。添到哪个脚本
这个是js,html代码,不涉及 php,更详细的操作方法可以参考 https://www.lovexint.com/archives/130/
这个怎么说,挺好,但是会影响速度,喜欢的朋友可以考虑从gif下手,
确实,对网站速度有影响,文中也提到了;gif的话,一方面图片太大,另一方面,自适应方面可能有所欠缺;一直想找个css实现,可惜没找到
不错的效果,很适合透明背景。
是的,不过对网页性能有点影响,影响加载速度,CPU和内存占用都会升高
very nice!!!