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Javascript Constellation Background
/*!
* @version 1.2.2
* @author Acauã Montiel <contato@acauamontiel.com.br>
* @license http://acaua.mit-license.org/
*/
/*
* requestAnimationFrame pollyfill
*/
if (!window.requestAnimationFrame) {
window.requestAnimationFrame = (window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.msRequestAnimationFrame || window.oRequestAnimationFrame || function (callback) {
return window.setTimeout(callback, 1000 / 60);
});
}
(function ($, window) {
/**
* Makes a nice constellation on canvas
* @constructor Constellation
*/
function Constellation (canvas, options) {
var $canvas = $(canvas),
context = canvas.getContext('2d'),
defaults = {
star: {
color: 'rgba(255, 255, 255, .5)',
width: 1
},
line: {
color: 'rgba(255, 255, 255, .5)',
width: 0.2
},
position: {
x: 0, // This value will be overwritten at startup
y: 0 // This value will be overwritten at startup
},
width: window.innerWidth,
height: window.innerHeight,
velocity: 0.1,
length: 100,
distance: 120,
radius: 150,
stars: []
},
config = $.extend(true, {}, defaults, options);
function Star () {
this.x = Math.random() * canvas.width;
this.y = Math.random() * canvas.height;
this.vx = (config.velocity - (Math.random() * 0.5));
this.vy = (config.velocity - (Math.random() * 0.5));
this.radius = Math.random() * config.star.width;
}
Star.prototype = {
create: function(){
context.beginPath();
context.arc(this.x, this.y, this.radius, 0, Math.PI * 2, false);
context.fill();
},
animate: function(){
var i;
for (i = 0; i < config.length; i++) {
var star = config.stars[i];
if (star.y < 0 || star.y > canvas.height) {
star.vx = star.vx;
star.vy = - star.vy;
} else if (star.x < 0 || star.x > canvas.width) {
star.vx = - star.vx;
star.vy = star.vy;
}
star.x += star.vx;
star.y += star.vy;
}
},
line: function(){
var length = config.length,
iStar,
jStar,
i,
j;
for (i = 0; i < length; i++) {
for (j = 0; j < length; j++) {
iStar = config.stars[i];
jStar = config.stars[j];
if (
(iStar.x - jStar.x) < config.distance &&
(iStar.y - jStar.y) < config.distance &&
(iStar.x - jStar.x) > - config.distance &&
(iStar.y - jStar.y) > - config.distance
) {
if (
(iStar.x - config.position.x) < config.radius &&
(iStar.y - config.position.y) < config.radius &&
(iStar.x - config.position.x) > - config.radius &&
(iStar.y - config.position.y) > - config.radius
) {
context.beginPath();
context.moveTo(iStar.x, iStar.y);
context.lineTo(jStar.x, jStar.y);
context.stroke();
context.closePath();
}
}
}
}
}
};
this.createStars = function () {
var length = config.length,
star,
i;
context.clearRect(0, 0, canvas.width, canvas.height);
for (i = 0; i < length; i++) {
config.stars.push(new Star());
star = config.stars[i];
star.create();
}
star.line();
star.animate();
};
this.setCanvas = function () {
canvas.width = config.width;
canvas.height = config.height;
};
this.setContext = function () {
context.fillStyle = config.star.color;
context.strokeStyle = config.line.color;
context.lineWidth = config.line.width;
};
this.setInitialPosition = function () {
if (!options || !options.hasOwnProperty('position')) {
config.position = {
x: canvas.width * 0.5,
y: canvas.height * 0.5
};
}
};
this.loop = function (callback) {
callback();
window.requestAnimationFrame(function () {
stats.begin(); // Only for Stats
this.loop(callback);
stats.end(); // Only for Stats
}.bind(this));
};
this.bind = function () {
$canvas.on('mousemove', function(e){
config.position.x = e.pageX - $canvas.offset().left;
config.position.y = e.pageY - $canvas.offset().top;
});
};
this.init = function () {
this.setCanvas();
this.setContext();
this.setInitialPosition();
this.loop(this.createStars);
this.bind();
};
}
$.fn.constellation = function (options) {
return this.each(function () {
var c = new Constellation(this, options);
c.init();
});
};
})($, window);
$('#background').constellation({
star: {
width: 1
},
line: {
color: 'rgba(255, 0, 0, .5)'
},
radius: 250
});
<!doctype html>
<html class="no-js" lang="en">
<head>
<meta charset="utf-8" />
<meta http-equiv="x-ua-compatible" content="ie=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<canvas id="background"></canvas>
<script src="constellation.js"></script>
</body>
</html>
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