From cocos2d to box2d? « cocos2d for iPhone

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From cocos2d to box2d?

(20 posts) (5 voices)

Started 11 months ago by Aorata
Latest reply from Aorata

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Aorata
Member

Hi peeps, I have a question.
I made a game in Cocos2d, but when the game gets crazy and intense (the player shooting MANY bad guys at the same time) my collision method seems to fail. I used simple collisions technique, getting a rectangle from each of the sprites and running a method that erases them when they are intersected....
As I've read, this only works for few collisions at a time, the method can only do so much. I've also read that you can use Box2d for "advanced collisions"...

SOOOoo...

How do I move my project from cocos2d to box2d to implement advanced collisions?

Thanks in advance!

Posted 11 months ago #
bazcocos
Member

Well, theres Ray's great article:
how-to-use-box2d-for-just-collision-detection-with-cocos2d

I'd be tempted to try to optimise what you have first, its not like box2d is trivial to add.
Perhaps some kind of pre-sorted lists or other restrictions to reduce the brute-force checking of every collision every frame?

Posted 11 months ago #
Aorata
Member

@bazcodos

Thanks for the fast reply. What I get from those tutorials (I've seen them before) is that I have to create a new project with the Box2d template... and then copy all my code from cocos2d to box2d?

Posted 11 months ago #
bazcocos
Member

I could be wrong, but if you look at a box2d project made from the template, the only difference is it brings in those box2d src files. I dont think you need to make a new project, just add those same files. (though I sometimes create new projects to avoid any potential issues, its a clean starting point).

edit - remember that box2d is cpp, so your src files which use those headers must have .mm extension to compile.

Posted 11 months ago #
Aorata
Member

Thanks for that idea, I'll go ahead and try it.

Still, if someone else has something to say, SAY IT! lol

Posted 11 months ago #
RelicaGames
Member

Well another thing to consider is that cocos2D comes with a proximity manager that can be used for checking collisions, but I'm still not sure how that compares to using box2D for collisions. It's probably a lot easier to set up though! although now that there is a box2D manager being made (like the chipmunk space manager), box2D is a lot easier to add in to a project and setup!

Posted 11 months ago #
Aorata
Member

I need instructions of how to add Box2D to a project, because I failed miserably .

Bear in mind that the project is already created, and I really don´t want to start from scratch.

Posted 11 months ago #
RelicaGames
Member

That should be fine, I added box2D to my project without starting a new one, and it was easy enough. But what have you done so far? All you have to do is drop in the box2D folder into the project. And then if you get loads of errors, then you have to add a Header Search Path of "." (without the quotations), and make it recursive. Also for any src file that you import box2D you have to change it from .m to .mm like bazcocos said. Of course you may have done all this anyway! so would be good to know where you are with it.

Once you've added it in and it compiles ok, then you just need to follow some examples of how to set it up, or if you want to make it even easier, then you could try using CCBox2D, which is what I'm using, and is done very well and makes it really very easy to use!

Posted 11 months ago #
pfg2009
Member

@RelicaGames: ProximityManager? What is that? Do tell. A recent addition perhaps?

Posted 11 months ago #
RelicaGames
Member

Its in the extras folder in the cocos2d download, but its not a recent addition, so would need updating to the latest version fo cocos, but its not that hard. But its nice and easy to setup, and basically you add objects to it, such as enemies for example, and then the player can easily get an array of all enemies within a certain range. It's a lot more efficient then looping through all the enemies to check for collisions, because not all enemies are even near the player at all times. However I really don't know how it compares to box2D for collisions... it's just a lot simpler to setup. It's created by @slipster216.

Posted 11 months ago #
Aorata
Member

@RelicaGames
I've done nothing actually, I did it once, got thousands of errors and just gave up. I'm going to try again when I get more time. College sucks balls.
Anyway, thanks for your instructions, as soon as I do it I'll post a reply here

Posted 11 months ago #
timTheMystic
Member

Where ever you use Box2d, make sure your have #import "Box2D.h" in your header files to prevent those errors.

Posted 11 months ago #
Aorata
Member

I'm getting 2500 errors, I already did the .m to .mm change, I imported the box2d.

Now what_

Posted 11 months ago #
RelicaGames
Member

Are the errors related to finding the files? ones with folder paths in them? if so you need to add a header search path (in the build settings) of "." (without quotes) and make it recursive by ticking that box. That should fix those problems if its what I'm thinking it is!

Posted 11 months ago #
Aorata
Member

ld: file not found: /Users/eduardoacedo/Desktop/DontEatTheOctopus/build/DontEatTheOctopus.build/Debug-iphonesimulator/DontEatTheOctopus.build/Objects-normal/i386/main.o /Users/eduardoacedo/Desktop/DontEatTheOctopus/build/DontEatTheOctopus.build/Debug-iphonesimulator/DontEatTheOctopus.build/Objects-normal/i386/Don_tEatTheOctopusAppDelegate.o
collect2: ld returned 1 exit status

Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/llvm-g++-4.2 failed with exit code 1

I guess... I'm so fed up with this error.

Posted 11 months ago #
Aorata
Member

@RelicaGames

What does this mean

Header Search Path of "." (without the quotations), and make it recursive

Posted 11 months ago #
RelicaGames
Member

Basically you want to go into build settings (and I had to do this for both my project and my games target)...
Search for 'Header Search Paths'
In the space next to it, double click to bring up the window for that
Add a new entry, check the box for recursive and add a dot to the right side.

If it still doesn't work, try doing the same thing for all your targets. Also you've changed the file where you've imported box2d to .mm, but have you also changed any other files that import that file?

Posted 11 months ago #
Aorata
Member

Yep, changed all .m to .mm
Added the box2d folder, did the header thing you just explained...

Maybe I did something wrong when I changed all the files or copied the classes, I´m going to try again and I´ll post back.

I don't know If I'm being stupid or what, but this is really hard lol.

Posted 11 months ago #
RelicaGames
Member

When you added the header search path, did you do it for all the targets? In xcode4, there's that list to the left of the settings, with different targets for your game and for cocos2D (assuming its set out this way for you too) so you could try doing the same for all if you haven't.

To test if this is what is even causing the errors, you could just change one of the includes in the main box2D.h from something like this <box2D/Common/b2Settings.h> to "b2Settings.h", and if you do that with a few of them and see if it makes a difference to the number of errors, then it's a good chance that they're whats causing the problems, so it would be to do with those header search paths. Also if you search for adding box2D to a project, then I believe there are others in the forums that have given small tutorials about how to do so, so maybe they will help too!

Posted 11 months ago #
Aorata
Member

Finaly got it, it was very simple really, I must have messed up the files when I was copying them. Thanks for your help guys.

Posted 11 months ago #

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