Question

I am creating a bunch of sprites from label textures dynamically and that is working fine. I have a few methods which I can use to tap a sprite and make it ‘jiggle’ then I can drag them around the screen. My problem is that I needed to add a Chipmunk shape to the sprites so that they don’t overlap and they push each other out of the way. Once I add the shape to the sprites, then my methods for selecting/dragging the sprites no longer works. I am a bit lost.

This is the method used for creating the sprites/shapes.

-(void) addNewSpriteX: (float)x y:(float)y wordIndex:(int)i
{
    CCLabelTTF *label;

    if ( i == 0 )
    {
        label = [CCLabelTTF labelWithString:[[words objectAtIndex:i] uppercaseString] fontName:[self getRandomFont] fontSize:kFontSize];
    }
    else
    {
        label = [CCLabelTTF labelWithString:[[words objectAtIndex:i] uppercaseString] fontName:[self getRandomFont] fontSize:[self getFontSize:[[counts objectAtIndex:0] intValue] andCurrentCount:[[counts objectAtIndex:i] intValue]]];
    }

    wordSprite = [CCSprite spriteWithTexture:[label texture]];
    // ask director the the window size
    wordSprite.color = [self getRandomColor];

    wordSprite.position =  ccp( x, y );

    // FROM HERE TO THE NEXT COMMENT IS WHERE I AM ADDING THE SHAPE AND BODY (DOING IT WRONG?)
    CGPoint p1 = CGPointMake(-wordSprite.contentSize.width/2, -wordSprite.contentSize.height/2);
    CGPoint p2 = CGPointMake(-wordSprite.contentSize.width/2, +wordSprite.contentSize.height/2);
    CGPoint p3 = CGPointMake(+wordSprite.contentSize.width/2, +wordSprite.contentSize.height/2);
    CGPoint p4 = CGPointMake(+wordSprite.contentSize.width/2, -wordSprite.contentSize.height/2);

    int num = 4;
    CGPoint verts[] = {p1, p2, p3, p4};

    cpBody *body = cpBodyNew(50.0, INFINITY);


    body->p = wordSprite.position;
    cpSpaceAddBody(space, body);

    cpShape* shape = cpPolyShapeNew(body, num, verts, cpvzero);
    shape->e = 0.5f; shape->u = 0.5f;
    shape->data = wordSprite;

    cpSpaceAddShape(space, shape);
    // END SHAPE CREATION

    [movableSprites addObject:wordSprite];

    [self addChild:wordSprite];

}

These are the methods I use for selecting and moving the sprites around (which no longer function after adding the shape/body).

- (void)selectSpriteForTouch:(CGPoint)touchLocation {
    CCSprite * newSprite = nil;
    for (CCSprite *sprite in movableSprites) {
        if (CGRectContainsPoint(sprite.boundingBox, touchLocation)) {            
            newSprite = sprite;
            break;
        }
    }    
    if (newSprite != wordSprite) {
        [wordSprite stopAllActions];
        [wordSprite runAction:[CCRotateTo actionWithDuration:0.1 angle:0]];
        CCRotateTo * rotLeft = [CCRotateBy actionWithDuration:0.1 angle:-4.0];
        CCRotateTo * rotCenter = [CCRotateBy actionWithDuration:0.1 angle:0.0];
        CCRotateTo * rotRight = [CCRotateBy actionWithDuration:0.1 angle:4.0];
        CCSequence * rotSeq = [CCSequence actions:rotLeft, rotCenter, rotRight, rotCenter, nil];
        [newSprite runAction:[CCRepeatForever actionWithAction:rotSeq]];            
        wordSprite = newSprite;
    }
}

- (BOOL)ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event {    
    CGPoint touchLocation = [self convertTouchToNodeSpace:touch];
    [self selectSpriteForTouch:touchLocation];      
    return TRUE;    
}

- (CGPoint)boundLayerPos:(CGPoint)newPos {
    CGPoint retval = newPos;
    retval.x = MIN(retval.x, 0);
    retval.x = MAX(retval.x, -background.contentSize.width+size.width); 
    retval.y = self.position.y;
    return retval;
}

- (void)panForTranslation:(CGPoint)translation {    
    if (wordSprite) {
        CGPoint newPos = ccpAdd(wordSprite.position, translation);
        wordSprite.position = newPos;
    } else {
        CGPoint newPos = ccpAdd(self.position, translation);
        self.position = [self boundLayerPos:newPos];      
    }  
}

- (void)ccTouchMoved:(UITouch *)touch withEvent:(UIEvent *)event {       
    CGPoint touchLocation = [self convertTouchToNodeSpace:touch];

    CGPoint oldTouchLocation = [touch previousLocationInView:touch.view];
    oldTouchLocation = [[CCDirector sharedDirector] convertToGL:oldTouchLocation];
    oldTouchLocation = [self convertToNodeSpace:oldTouchLocation];

    CGPoint translation = ccpSub(touchLocation, oldTouchLocation);    
    [self panForTranslation:translation];    
}

Answer 1

If you are working with chipmunk + TouchMove, you should use, cpMouse.
Check out http://www.cocos2d-iphone.org/forum/topic/4936

There were two examples on Github,
1) Kerchink (used with new version) which is removed :(,
2) Grabbed or Grabbed to (used with old version).http://code.google.com/p/grabbed/

cpMouse is just invisible body which connected with on touchBegan, with the object on the toucharea, using PinJoints,SlideJoints etc. When you touchMoved, the object connected with cpMouse also get moved.

If you would like to go without cpMouse and with your code, — you may be using step() function to iterate your chipmunk, which continue sly changes the all sprite’s rotation and position. So if you are trying change the position of the sprites, step function will override the rotation and position and there will be no effect.