JavaScript

语言：

JaveScriptBabelCoffeeScript

确定

// RequestAnimationFrame shim by Paul Irish

window.requestAnimFrame = (function() {

return window.requestAnimationFrame ||

window.webkitRequestAnimationFrame ||

window.mozRequestAnimationFrame ||

function(callback) {

window.setTimeout(callback, 1000 / 60);

};

})();

/* VARS

----------------------------------------------- */

var canvas = document.getElementById('canvas'),

ctx = canvas.getContext('2d'),

width,

height,

centerY,

centerX,

TWO_PI = Math.PI * 2,

movePixels = 0,

moveDirection = 1,

moveThreshold = 151;

function Pattern(color, number, padding, stroke) {

this.lineNum = number;

this.padding = padding;

this.color = color;

this.stroke = stroke;

this.dx = 0;

this.dy = 0;

}

Pattern.prototype.draw = function(dx, dy) {

ctx.strokeStyle = this.color;

ctx.lineWidth = this.stroke;

if (dy) {

this.dy = dy;

}

if (dx) {

this.dx = dx;

}

for (var i = 0; i < this.lineNum; i += 1) {

ctx.beginPath();

ctx.arc(centerX + this.dx, centerY + this.dy, (i * this.padding), 0, TWO_PI, false);

ctx.stroke();

}

}

function draw() {

requestAnimFrame(draw);

ctx.clearRect(0, 0, canvas.width, canvas.height);

var firstPattern = new Pattern('#E84D17', 20, 8, 3);

var secondPattern = new Pattern('#1787E8', 20, 8, 3);

firstPattern.draw();

secondPattern.draw(movePixels);

if (movePixels === moveThreshold || movePixels === -moveThreshold) {

moveDirection = moveDirection * -1;

}

movePixels += moveDirection;

}

/* INIT

----------------------------------------------- */

canvasSize();

ctx.globalCompositeOperation = 'multiply';

draw();

/* UTILITIES

----------------------------------------------- */

function canvasSize() {

width = window.innerWidth;

height = window.innerHeight;

centerY = height / 2;

centerX = width / 2;

canvas.height = height;

canvas.width = width;

}