A fast, easy to use, free, and community supported 2D game engine
For anyone interested in using Chipmunk only for collision detection, and not for any physics, then I have done up a sample project.
This may not be the best option for collision detection, and I may not have done it the best way, but for anyone who is interested - you can view the thread here:
http://www.cocos2d-iphone.org/forum/topic/364
The sample is here:
http://files.me.com/shivaz/5jb01u
Do what you like with it, grab it while you can.
Justin
I'm getting an uncaught exception before the demo even loads on Simulator. I've tried all versions of the SDK. Any suggestions?
Thanks again for putting this together! Its already given me some ideas for the future!
P.S. I posted this in the other thread before I saw this one...sorry.
-Sunsnu
Sorry about that Sunsu - fps_images.png was in there originally - but got dropped when I was lightening it up! Surprised it made it crash though - thought I removed all reference to it.
@jd. Absolutely, the collision detection will work with rotation - and you can make much more complex bodies - instead of just the box in the demo. There was a great tutorial some where that has a ball and a red bowl - the bowl is made up of 4 or 5 pieces. Explains all about making complex shapes with chipmunk. Any one know which one I mean? Lost it sorry.
Justin
When you create your sprites / shapes you could associate your sprites with a shape by putting the sprite pointer in the cpShape.data member. Or you could do the reverse and add a void* data member to the CocosNode class (either with a new class or modifying the source directly).
Don't know if that suggestion helps, I didn't actually look at that code yet, just sounded like a familiar question.
@virtudude - yes absolutely! As SmallMike mentioned - when you add the cpShape to the sprite you store a link to the sprite in data.
So in the Collision function you can access the sprite as such:
Sprite *sprite = a->shape->data;
if( sprite ) {
// Do something with your sprite.
}
Korki696
Member
Hey so I have a quick question. im still learning chipmunk but the one think i cant seem to figure out is that i modified it a little to have 3 moving sprites now. Im having a couple problems.
First: whenever i move a sprite it is very slow and choppy. Has anyone else had this problem.
Second which is my main problem i want to fix is that i like the collision detection between these but right now they just go through each other. What i have are three characters and i want them to be able to run into each other so they have to go around.
Thanks
-Lars
Hello Lars
Should be able to move sprites smoothly, can you send me the code changes you have made - and I will test here?
Secondly, it sounds like you are wanting to use Chipmunk for more than just collision detection! This project has set it up just for that. You will need to add the body to the space, and update the eachShape function so that it updates the sprite position and rotation to copy the shape - the reverse of what is currently setup.
You are better off checking out Grabbed or Thrown - http://www.cocos2d-iphone.org/wiki/doku.php/prog_guide:sample_games
They use cpMouse I believe for movement.
Korki696
Member
hey so i looked into grabbed and thrown. thrown isnt compiling for me but grabbed is the only thing i see that will be a problem is that there is no moveTo feature where it follows the mouse not just move with the mouse. Is there a way i can do this by modifiyng the current code and using the ccTouchedBegan, Moved, and Ended methods?
Thanks
-Lars
Can't help much with those samples (have only had a quick look at them), but I did have another play with my sample - and there is something you can do, that might achieve what you want. Haven't fully tested it. But if you replace your spriteToSpriteCollision with the following - it will repel the collided sprites away from each other. You could add any code in here to stop the current action - or add a new one. Its just a start.
static int spriteToSpriteCollision(cpShape *a, cpShape *b, cpContact *contacts, int numContacts, cpFloat normal_coef, void *data)
{
// MotionLayer *motionLayer = (MotionLayer*) data; // access to the layer.
// a->body->p // do something with the position of a
// b->body->v // do something with the velocity of b
MySprite *sprite = a->data;
MySprite *sprite2 = b->data;
if( sprite ) {
// Calculate the distance between anchor points - then move the sprites that much away from each other. Could probably make them move half as much - up to you.
[sprite setPosition:ccp(2*a->body->p.x - b->body->p.x, 2*a->body->p.y- b->body->p.y)];
[sprite2 setPosition:ccp(2*b->body->p.x - a->body->p.x, 2*b->body->p.y- a->body->p.y)];
// [sprite setCollided:YES]; // if you have a collided property.
// [sprite2 setCollided:YES];// on your sprites - and want to set off
NSLog(@"Collided!"); // audio or something.
}
return 0;
}Then in that case, your
cpSpaceAddCollisionPairFunc(space, 1, 2, &spriteToWallCollision, self);
Would be 1, 2 or something. Where 1 is your static object and 2 is your moving object.
Then "a" is your wall, and "b" is your sprite.
So change your collision function to be:
static int spriteToWallCollision(cpShape *a, cpShape *b, cpContact *contacts, int numContacts, cpFloat normal_coef, void *data)
{
MySprite *sprite = b->data;
MySprite *wall = a->data;
if( sprite ) {
[sprite stopAllActions];
[sprite setPosition:ccp(b->body->p.x-(b->body->p.x-a->body->p.x)/2 + 2, b->body->p.y-(b->body->p.y-a->body->p.y)/2 + 2)];
}
return 0;
}Probably barking up the wrong tree. The move is just so the collisions stop. What you really need to do is get the b->body->p.x - a->body->p.x and find out if it is positive or negative. Then add or take 1 from the current x of b. Then repeat for the y. That will make it look like the object just stops.
Korki696
Member
Ok so that will solve part of my problem but now that i read my post again it was a little unclear. what i have are three characters that you can select and move. what i want to happen is that when you move one character into another they will not be able to go anywhere unless they go around.
I would do this all in chipmunk the real way but i havent found any way to have a moveTo type of feature
-Lars
Okay, well good luck with that! You would think there would be a way to run actions directly on a cpBody/cpShape - but I don't think there is :(
Maybe if you check out the actioncode in the new release candidate, there might be something there. Or maybe have to roll your own actions for chipmunk.
If it is only a moveTo that you need - then that might not be needed.
You could set the velocity of the cpBody - and then when it gets where you want, set the velocity to 0. Just thinking out loud.
symadept
Member
Hi Shivaz,
I am facing the same kind of problem.
I have issued MoveTo action on one sprite to the location of the other sprite. This should result in the callback of the collision, this is happening with me now. But What I could see is that the callback is called before the object actually reached there because of which my object disappears before the other one reaches. But I am scared why this is happening...
Waiting for your response...
Regards
Mustafa
symadept
Member
Hi,
When I was posting this then one point strike to me.
Actually while moving the sprite to the objects location, I am doing this way.
`
//Moving sprite
id actionBy = [MoveTo actionWithDuration:0.5f position: objectPos];
[_bulletSprite runAction: actionBy];
//Moving body
_bulletBody->p = bulletPos;
_bulletBody->v = cpv(0,0);
I guess here is the catch, moving the body. Now what happens is that Body is moving faster than the Sprite because of which I could see CollisionDetect callback is called in which I am hiding the Object and the Sprite actually moves bit later. Now can anyone tell me, how can I move Sprite & Body together with same duration.
Regards
Mustafa
symadept@gmail.com
symadept
Member
Can anyone please look into my issue. I want to move the bullet from Shooter to the Object. If I use body position change, then it is so fast I can't see any animation. If I use MoveTo then the actual body is not moved.
How can I do this.
Regards
mustafa
symadept@gmail.com
If you use chipmunk for your bullets, you can do something like this:
-(void) fireFromTo: (float) x y:(float)y a:(float)a
{
bulletBody->p = cpv(x,y);
bulletBody->v = cpv(cos(a)*480, sin(a)*320);
}You provide the start x,y and the angle.
You can take the bullet code from this site http://morethanmachine.com/macdev/?p=91 and just add my method and call it instead of their fireFromX method (which doesn't account for angle).
Anybody know if you could use this chipmunk collision in conjunction with a collision MAP?
I already have my level laid out for collision using a mask ( see http://www.cocos2d-iphone.org/forum/topic/1188 ), and would like to check against that map with my moving sprites using this Chipmunk example. I just don't know if they will play well together.
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