sprite not rotating correctly (cocos2d) - iphone

Question

I have a turret on top of a tank base, both inside the same sprite sheet with frames correctly specified. When i build and run the project, I want the turret to rotate along the anchor point of the center of the tank. The turret is a child of the tank so that they will stay together when moving. However, when I try to rotate it, the turret seems to set its anchor point somewhere far off into the distance, like this:
This is my init:
- (id)initWithLayer:(HelloWorldLayer *)layer type:(int)type hp:(int)hp {
NSString *spriteFrameName = [NSString stringWithFormat:#"tank%d_base.png", type];
if ((self = [super initWithSpriteFrameName:spriteFrameName])) {
_layer = layer;
_type = type;
self.hp = hp;
_turret = [CCSprite spriteWithSpriteFrameName:[NSString stringWithFormat:#"tank%d_turret.png", type]];
_turret.anchorPoint = ccp(0.5, 0.25);
[self scheduleUpdateWithPriority:-1];
[self addChild:_turret];
_turret.position = ccp(40, 50);
}
return self;
}
and I rotate the sprite here (I use a 360 degree shooting range)
- (void)shootToward:(CGPoint)targetPosition {
//CGPoint offset = ccpSub(targetPosition, self.position);
float x = abs(targetPosition.x) - self.position.x;
float y = abs(targetPosition.y) - self.position.y;
float angle;
float angleDegrees;
if (x < 0 && y > 0) {
angle = atanf(y/x);
angleDegrees = -CC_RADIANS_TO_DEGREES(angle) - 90;
}
else if (x < 0 && y < 0) {
angle = atanf(y/x);
angleDegrees = -CC_RADIANS_TO_DEGREES(angle) - 90;
}
else if (x > 0 && y < 0) {
angle = atanf(y/x);
angleDegrees = 90 - CC_RADIANS_TO_DEGREES(angle);
}
else if(x > 0 && y > 0) {
angle = atanf(y/x);
angleDegrees = 90 - CC_RADIANS_TO_DEGREES(angle);
}
switch (_layer.rotateInt) {
case 0:
angleDegrees = angleDegrees;
break;
case 1:
angleDegrees = angleDegrees+ 180;
break;
case 2:
angleDegrees = angleDegrees;
break;
case 3:
angleDegrees = angleDegrees + 90;
break;
case 4:
angleDegrees = angleDegrees - 90;
break;
default:
break;
}
NSLog(#"%f",angleDegrees);
_turret.rotation = angleDegrees;

Answer 1

Hmm. The only thing that I think could be causing this is that the turret asset is not centered or has a lot of blank space. That said, I'd try playing with the anchor point of the turret.

Answer 2

Since the turret is a child of the tank, this:
_turret.position = ccp(40, 50);
offsets the turret by 40x50 away from the tank's origin (lower left corner of bounding box). Try settings the position so the turret is centered on the tank:
_turret.position = ccp(tank.contentSize.width * tank.anchorPoint.x,
tank.contentSize.height * tank.anchorPoint.y);