Untitled

<canvas></canvas>

html, body {

  width: 100%; height: 100%;

  background: #333;

}

canvas {

  display: block;

}

(function() {

  // rAF

  window.requestAnimationFrame = function() {

    return window.requestAnimationFrame ||

      window.webkitRequestAnimationFrame ||

      window.mozRequestAnimationFrame ||

      window.msRequestAnimationFrame ||

      window.oRequestAnimationFrame ||

      function(f) {

        window.setTimeout(f,1e3/60);

      }

  }();

  var canvas = document.querySelector('canvas');

  var ctx = canvas.getContext('2d');

  var W = canvas.width = window.innerWidth;

  var H = canvas.height = window.innerHeight;

  // Our SpaceShip Constructor

  var SpaceShip = function() {

    // x/y positions

    this.x = 200;

    this.y = 100;

    this.radius = 40;

    // How many wings/blades or whatever you want to call it

    this.wing_count = 3;

    // Math.PI*2 === 360 degrees

    // 360 / 3 = 120 degrees

    // So every 120 degrees will have 1 hand/blade

    // of 60 degrees (half of 120)

    this.steps = Math.PI*2 / this.wing_count;

    this.color = 'hsl(0,100%,50%)';

    // We can try changing color after EVERY rotation

    // would be cool!

    this.hue = 0; // initial hue

    // This is the target hue we'll reach

    // during (at start) the first rotation

    this.hue_target = parseInt( Math.random()*360 );

    // Lets mess with the angle now

    this.angle = 0;

    // Manipulating speed - seems good!

    this.rotation_speed = 0.06;

    this.draw = function(ctx) {

      // But we want to do this after every rotation

      if (this.angle > Math.PI*2) {

        // Kind of reset the angle when its more

        // than 360 degrees.

        this.angle -= Math.PI*2;

        // Choose a random hue target now

        this.hue_target = parseInt( Math.random()*360 );

        // ... and we made it :)

      }

      // You notice initially there's a color change ?

      // Why this (hue_target - hue) * random_numer ?

      // Well, we basically measure the distance that we

      // have to travel, from initial to target and multiple

      // that by an "easing" factor.

      // This causes "easing" effect when changing from initial

      // to target color, i.e., it starts with high speed

      // and as it progresses, the spead decreases until

      // it reaches the target.

      // We just learnt how to implement Easing in html5 canvas!

      this.hue += (this.hue_target - this.hue) * 0.05;

      this.color = 'hsl(' + this.hue + ',100%,50%)';

      ctx.strokeStyle = this.color;

      // Setting a line width

      ctx.lineWidth = 15;

      // Time to rotate this thing

      // Since ctx.rotate() will rotate the entire 2D context

      // and not just the arc's, we'll have to save

      // our current drawing state into the stack.

      ctx.save();

      // as you can see entire context was rotated

      // we'll fix this by first translating

      // The x/y values that we pass to translate()

      // is the same as the ones we passed to ctx.arc below

      ctx.translate(this.x, this.y);

      // The entire thing became a circle :P

      // cuz we never cleared after each rendering of frame

      this.angle += this.rotation_speed;

      ctx.rotate(this.angle);

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

        ctx.beginPath();

        // For arc, the new x/y pos will be 0,0

        ctx.arc(

          0,

          0,

          this.radius,

          i*this.steps,

          i*this.steps + this.steps/2,

          false

        );

        ctx.stroke();

        ctx.closePath();

      }

      // ... and restore here

      ctx.restore();

      // A rounded body in the center

      ctx.beginPath();

      ctx.fillStyle = 'black';

      ctx.arc(this.x, this.y, 20, 0, Math.PI*2, false);

      ctx.fill();

      ctx.closePath();

    };

  };

  // Create a spaceship object

  var ship = new SpaceShip();

  // Setting proper x/y to center it

  ship.x = W/2;

  ship.y = H/2;

  (function renderFrame() {

    window.requestAnimationFrame(renderFrame);

    // Magik! We dont need so much speed though...

    ctx.clearRect(0,0,W,H);

    ship.draw(ctx);

  }());

}());