Limit Sprite Rotation - Cocos2d - iphone

Question

I have two hands on either side of the screen that do not move at all and two thumbs that rotate 360 degrees. I want to limit the thumbs rotation, meaning I only need them to be able to rotate like normal thumbs. I am new to cocos2d so any help will be greatly appreciated. Here is what I have so far
#import "cocos2d.h"
#interface GameScene : CCLayer {
CGFloat lthumbRotation, rthumbRotation;
CCSprite *lthumb, *rthumb;
}
+(CCScene *) scene;
#end
------------------------------------
#import "GameScene.h"
#implementation GameScene
+(CCScene *) scene
{
CCScene *scene = [CCScene node];
GameScene *layer = [GameScene node];
[scene addChild: layer];
return scene;
}
-(id) init
{
if ((self = [super init]))
{
lthumb = [CCSprite spriteWithFile:#"lthumb.png" rect:CGRectMake(0,0, 145, 59)];
lthumb.position = ccp(100, 140);
lthumb.anchorPoint = ccp(0.3, 0.8);
[self addChild:lthumb z:0];
rthumb = [CCSprite spriteWithFile:#"rthumb.png" rect:CGRectMake(0,0, 145, 59)];
rthumb.position = ccp(380, 140);
rthumb.anchorPoint = ccp(0.7, 0.8);
[self addChild:rthumb z:0];
[self scheduleUpdate];
}
return self;
}
-(void)update:(ccTime)delta
{
lthumb.rotation = lthumbRotation;
rthumb.rotation = rthumbRotation;
}
- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
}
- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
//acquire the previous touch location
CGPoint firstLocation = [touch previousLocationInView:[touch view]];
CGPoint location = [touch locationInView:[touch view]];
//preform all the same basic rig on both the current touch and previous touch
CGPoint touchingPoint = [[CCDirector sharedDirector] convertToGL:location];
CGPoint firstTouchingPoint = [[CCDirector sharedDirector] convertToGL:firstLocation];
CGPoint firstVector = ccpSub(firstTouchingPoint, rthumb.position);
CGFloat firstRotateAngle = -ccpToAngle(firstVector);
CGFloat previousTouch = CC_RADIANS_TO_DEGREES(firstRotateAngle);
CGPoint vector = ccpSub(touchingPoint, rthumb.position);
CGFloat rotateAngle = -ccpToAngle(vector);
CGFloat currentTouch = CC_RADIANS_TO_DEGREES(rotateAngle);
//keep adding the difference of the two angles to the dial rotation
lthumbRotation += currentTouch - previousTouch;
rthumbRotation -= currentTouch - previousTouch;
}
- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
}
- (void) dealloc
{
CCLOG(#"%#: %#", NSStringFromSelector(_cmd), self);
[super dealloc];
}
#end
This lets both of the thumbs move at the same time in upward/downward angles with the anchor point at the bottom of the thumbs(acting like a joint).
I also need the thumbs rotation to reset back to 0 once the touches have ended.
Thanks in advance

Answer 1

In your ccTouchesMoved:withEvent: method, simply check to see if the new rotation is within a given threshold before applying it to your sprites.
Finally, in ccTouchesEnded:withEvent:, you can simply set the rotation values back to 0:
lthumbRotation = 0;
rthumbRotation = 0;