bounding a sprite in cocos2d

Question

am making a canon to fire objects. back of the canon the plunger is attached. plunger acts for set speed and angle. canon rotates 0-90 degree and plunger moves front and back for adjust speed. when am rotates the canon by touches moved its working fine. when plunger is pull back by touches moved and it rotates means the plunger is bounds outside of the canon.

how to control this:-

my code for plunger and canon rotation on touches moved. ( para3 is the canon , para6 is my plunger):-

    CGPoint touchLocation = [self convertTouchToNodeSpace:touch];
    CGPoint oldTouchLocation = [touch previousLocationInView:touch.view];
    oldTouchLocation = [[CCDirector sharedDirector] convertToGL:oldTouchLocation];
    oldTouchLocation = [self convertToNodeSpace:oldTouchLocation];
    if (CGRectContainsPoint(CGRectMake(para6.position.x-para6.contentSize.width/2, para6.position.y-para6.contentSize.height/2, para6.contentSize.width, para6.contentSize.height), touchLocation) && (touchLocation.y-oldTouchLocation.y == 0))
    {
        CGPoint diff = ccpSub(touchLocation, oldTouchLocation);
        CGPoint currentpos = [para6 position];
        NSLog(@"%d",currentpos);
        CGPoint destination = ccpAdd(currentpos, diff);
        if (destination.x < 90 && destination.x >70)
        {
            [para6 setPosition:destination];
            speed = (70 + (90-destination.x))*3.5 ;
        }

    }
if(CGRectIntersectsRect((CGRectMake(para6.position.x-para6.contentSize.width/8, (para6.position.y+30)-para6.contentSize.height/10, para6.contentSize.width, para6.contentSize.height/10)),(CGRectMake(para3.position.x-para3.contentSize.width/2, para3.position.y-para3.contentSize.height/2, para3.contentSize.width, para3.contentSize.height))))

            {

        [para3 runAction:[CCSequence actions:
                          [CCRotateTo actionWithDuration:rotateDuration angle:rotateDiff],
                          nil]];
        CGFloat plungrot = (rotateDiff);
        CCRotateTo *rot = [CCRotateTo actionWithDuration:rotateDuration angle:plungrot];
        [para6 runAction:rot];
    }
}

Answer 1

how about u do this that you use the [CCMoveTo actionWithDuration: position:] method??

Through this method you can easily control the speed by the "actionWithDuration" argument which takes integer values of time in seconds, while direction can be adjusted through "position" argument which takes ccp(x,y) as the values to the point you want your plunger to move to.

You can use it like this....

    CCSprite *plunger = [[CCSprite alloc] initWithFile:@"plunger.png"];
    plunger.position = ccp(240,240);
    [self addChild:plunger z:10];
    [plunger release];

    id = [CCMoveTo actionWithDuration:3 position:ccp(300,240)];

The values given are of my choice. You may use them to your accordance.

Hope it helps you....

Answer 2

I hope i understood the question correctly: if the problem is, that the cannon and plunger both rotate around their own center points, but you want them to rotate together, then the solution should be to make the plunger a child sprite of the cannon (this also makes the plugers position relative to the cannon) i.e.

[para3 addChild:para6]

then you only need to rotate the cannon and the plunger will be rotatet with it.

if i got your question totally wrong, maybe you could post a screenshot :-)