Comments on: Bouncing a Ball Around with HTML5 and JavaScript

By: akash

akash — Fri, 15 Jun 2012 06:50:52 +0000

hello,,i want some balls to be moving in a box but if someone moves the cursor to one of the ball then it should stop moving automatically and if we click on that ball then it should open some specified link.But it should be purely using javascript,css,html5 and jquery..
can anyone help?

By: Hitu

Hitu — Fri, 15 Jun 2012 05:46:48 +0000

Nice Article

By: Dovid G.

Dovid G. — Tue, 08 Nov 2011 14:57:39 +0000

@Jesse (If you’re still watching the comments)

What’s happening is this, suppose dx = 5.
If I were to declare x = -dx, that would mean x = -5.
Now if I declare x = -x, it’s like saying x equals negative negative 5 (x = – -5) which reverses the negative to a positive. So now x = 5. If I do x = -x again, then it’s back to negative 5, if I do it again then it’s positive 5.

So when the ball hits the wall dx reverses it self from positive to negative, or negative to positive, and it’s all accomplished by dx=-dx. For either it’s a true negative -dx or a positive -(-dx).

By: gauss11

gauss11 — Tue, 25 Oct 2011 21:31:01 +0000

Really cool.

Thanks

By: John L

John L — Tue, 27 Sep 2011 02:21:33 +0000

Your article was very helpful. Thanks.

By: Intizar

Intizar — Thu, 08 Sep 2011 12:55:25 +0000

really nice one. very helpful I was searching such type of tutorial

By: nithin

nithin — Wed, 27 Jul 2011 05:55:18 +0000

nice one really helpfull..

By: Jesse

Jesse — Sun, 17 Jul 2011 21:13:03 +0000

if( x280) dx=-dx;
if( y280) dy=-dy;
x+=dx;
y+=dy;

sorry meant this one

By: Jesse

Jesse — Sun, 17 Jul 2011 21:12:03 +0000

can someone please explain the logic behind the boundary logic..it works, but for some reason it doesn’t make sense…once x or y hits a wall dx becomes -dx or -dy..it’s supposed to stay negative then forever right?!

if( x280) dx=-dx;
if( y280) dy=-dy;
x+=dx;
y+=dy;

By: JS

JS — Sun, 05 Jun 2011 19:22:12 +0000

Great tutorial thanks! How would I go about replacing those balls with actual images (jpg/png)?