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From: Shayne O'Neill <shayne.one...@gmail.com>
To: cocos2d-iphone-discuss@googlegroups.com
In-Reply-To: <b5fe2f43-9f90-4fb0-8391-207d598bb...@s9g2000prg.googlegroups.com>
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Subject: Re: Strategies for collision detection.
Date: Fri, 5 Dec 2008 02:20:00 +0900
References: <B5CFEFDB-689E-4A79-988F-61C9C2680...@gmail.com>  <576671f4-ac39-4d9f-8960-190949b81...@g38g2000yqn.googlegroups.com>  <ef7a57a00811300930h666b12e7h29f77ab90bff6...@mail.gmail.com>  <996ec470811301027y3e59dad9r55dea39abf334...@mail.gmail.com>  <3522a0a2-04c6-4963-ac1b-072b8431e...@n10g2000yqm.googlegroups.com>  <c314e23d-e6fc-471f-9e3d-fcb6e761b...@r40g2000yqj.googlegroups.com>  <996ec470812030914o620668d3pc266bc8fd641b...@mail.gmail.com>  <06dbb5ef-01ea-402a-8a64-66c076fe3...@x8g2000yqk.googlegroups.com>  <996ec470812031021g3f0ec161ge1673affa401d...@mail.gmail.com>  <0ba6139d-0574-4cff-90d1-691a67dea...@n10g2000yqm.googlegroups.com>  <996ec470812031631r512075ddiebb547434b627...@mail.gmail.com>  <f74a265e-b327-4c83-a2df-e1b885881...@f20g2000yqg.googlegroups.com> <b5fe2f43-9f90-4fb0-8391-207d598bb...@s9g2000prg.googlegroups.com>


I had an idea on how to implement collision detection, and get touch  
handling as a freebie.

It strikes me that with this talk of collision detection, that a well  
concieved foundation for it would probably work well as the basis for  
a touch control api as well.

essentially if there was something like the ability to nominate  
something like a 'channel' or something that cocosnodes can be  
registered to, and if there is a collision on that channel, then that  
'channel' will then do a callback.

So basically  all the cocosnodes registered to the 'channel' tell the  
'channel' whenever their rect intersects with another rect in that  
channel which sends the rects to the callback.

So I could do something like

channel = [[cocosChannel  init] registerCallback:obj  
selector:selector(callback:)]

[[[[channel add:sprite1] add:sprite2] add:sprite3]

and from then on, if any of those sprites collided the object  
nominated in the channel would recieve a message like
[obj callback:<array of sprites>]

 From there one imagine a special cocosnode that exists as a singleton  
called something like cocosTouch, and all someone has to do is add  
that node to a channel, and if the user touches one of the sprites in  
that channel , the callback is triggered

So I could do

controls  = [[cocosChannel init] registerCallback:controller  
selector:selector(doControls:)]

[[[[controls add:leftArrowSprite] add:rightArrowSprite]  
add:upArrowSprite] add:downArrowSprite]

and whenever one of the 4 arrows is pressed, it calls the callback  
with a reference to the arrow pressed.

That'd make touch control really elegent, and it'd be very easy to  
implement as a side effect of adding collision detection.

Which kills 2 birds with one stone, as the saying goes.

I hope this all makes sense.

Shayne.