Creating 2-D Animations on Canvas - bouncing ball

In this tutorial, the following will be looked into on HTML5 canvas:

  • How to create a ball on HTML5 Canvas.
  • How to control its movement both horizontally and vertically.
  • How to stop the motion when the ball hits the floor.
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Interactive Bouncing Ball

In this example, several methods of context object are used to create a bouncing ball animation on canvas. It is fully interactive too.

The vertical movement of the ball is controlled by the value of a variable which goes down with the time. At the same time, the horizontal movement of the ball is controlled by another variable, which, increases with the time.





The Code for Interactive Bouncing Ball is as follows:

<script type="text/javascript">
var xx; var a=0; var b=10; var c=100; var x=0;
var canvas = document.getElementById('Canvas_One');
var context = canvas.getContext('2d');
resetting();
// print the title of the animation on canvas
function titling(){
context.font = '20pt Calibri';
context.fillStyle = 'green';
context.fillText('The Bouncing Ball', 100, 30);
}
// code for resetting
function resetting(){
c=100;a=0;x=0;
context.clearRect(0,0,400,300);
titling();
context.beginPath();
context.arc(80,100,20,0,2*Math.PI,false);
var grd = context.createRadialGradient(80, 100, 3, 80, 100, 18);
grd.addColorStop(0, '#8ED6FF');
grd.addColorStop(1, '#004CB3');
context.fillStyle = grd;
context.fill();
context.beginPath();
context.moveTo(0,122);
context.lineTo(100,122);
context.lineWidth=4;
context.strokeStyle="red";
context.stroke();
}
// code for dropping the ball
function dropping(){
a=a+b;
x=x+2.5;
if(a==c){b=-10;}
if(a==0){b=10;c=c-10;}
context.beginPath();
context.moveTo(0,122);
context.lineTo(100,142);
context.lineWidth=4;
context.strokeStyle="green";
context.stroke();
context.clearRect(0,0,400,300);
context.font = '20pt Calibri';
context.fillStyle = 'green';
context.fillText('The Bouncing Ball', 100, 30);
context.beginPath();
context.arc(80+x,180+(100-a),20,0,2*Math.PI,false);
var grd = context.createRadialGradient(80+x, 180+(100-a), 3, 80+x, 180+(100-a), 18);
grd.addColorStop(0, '#8ED6FF');
grd.addColorStop(1, '#004CB3');
context.fillStyle = grd;
context.fill();
if(c==20){window.clearInterval(xx);}
var aud=document.getElementById('audio1');
if(a==0 || a==10){ aud.play();}
}
// code for using the timer
function start_one(){
xx=window.setInterval('dropping()',80);
}
</script>

 

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