HTML5 Game - Canvas Animation Bobbing

Description

Bobbing
Demo

<!doctype html>  
<html>  
 <body>  
  <canvas id="canvas" width="400" height="400"></canvas>  
  <script>  

class Ball{  //from  w  w w.  j  a v  a2  s. co m
  constructor(radius, color) {
      if (radius === undefined) { radius = 40; }  
      if (color === undefined) { color = "#ff0000"; }  
      this.x = 0;  
      this.y = 0;  
      this.radius = radius;  
      this.rotation = 0;  
      this.scaleX = 1;  
      this.scaleY = 1;  
      this.color = color;  
      this.lineWidth = 1;  
    }  
      
    draw = function (context) {  
      context.save();  
      context.translate(this.x, this.y);  
      context.rotate(this.rotation);  
      context.scale(this.scaleX, this.scaleY);  
      context.lineWidth = this.lineWidth;  
      context.fillStyle = this.color;  
      context.beginPath();  
      //x, y, radius, start_angle, end_angle, anti-clockwise  
      context.arc(0, 0, this.radius, 0, (Math.PI * 2), true);  
      context.closePath();  
      context.fill();  
      if (this.lineWidth > 0) {  
        context.stroke();  
      }  
      context.restore();  
    }
}  
  window.onload = function () {  
    let canvas = document.getElementById('canvas'),  
        context = canvas.getContext('2d'),  
        ball = new Ball(),  
        angle = 0;  
  
    ball.x = canvas.width / 2;  
    ball.y = canvas.height / 2;  
  
    (function drawFrame () {  
      window.requestAnimationFrame(drawFrame, canvas);  
      context.clearRect(0, 0, canvas.width, canvas.height);  
  
      ball.y = canvas.height / 2 + Math.sin(angle) * 50;  
      angle += 0.2;  
      ball.draw(context);  
    }());  
  };  
  </script>  
 </body>  
</html>