Collision detection

[stormbind]

How best to perform collision detection in javascipt?

This is something that I have often wondered, but now I need it for a sites christmas decorations. What I need is a means of detecting when the sprite is over a static image.

The pixel positions could be measured and compared but that might be slow and unsuitable for web browsing

I'm thinking maybe I need a 2-bit collision map, for simpler detection without re-calculating the position of every element on the page.

Perhaps this is already done by the browser? Netscape 4.x document.layers is an example of a browser's reserved array of specific objects.

Is there anything similar in MSIE? Hopefully a built in array with all the IMG on the page?

Please share your knowledge or experiences of collisions

Thank you kindly!

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I'm willing to trade custom scripts for... [see profile]

 

[stormbind]

OK. I'll talk to myself then...

It's easy to collect the IMG tags in an array, and extracting their position and sizes... that leaves me with something like this:

img[0], img[1], img[2] (objects)

x[c] 100, 200, 120 (left)
y[c] 100, 200, 120 (top)
w[c] 100, 100, 100 (width)
h[c] 20, 20, 20 (height)

How do I create a map from those values?

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[simonchristieis]

Aren't you going about it the wrong way - shouldn't you been detecting what element the sprite is over?

As in if it moves over an table - nothing.
If it moves over an image the world explodes.

Not exactly sure how this would fly - it's easy once you can figure out an event handler for the sprite, I wonder if onMouseOver etc just work for the cursor ? Let me know when you find out.

Just a thought.