Rotating a Cocos2d sprite to match a joystick

Question

I'm using a SneakyJoystick in Cocos2d, and I'm trying to get a sprite to rotate to face the same direction as the joystick is pointed (this is top down).

I can get it to rotate to face it, but it snaps into position as the rotation is updated every frame or so.

How can I make the sprite rotate smoothly towards the target angle, without jumping to it? I wasn't able to figure out how to do this with a CCRotateTo because the angle to rotate towards could change at any time.

Answer 1

I ended up fixing this simply by using a rotation method that I made, which rotates the node/sprite in the correct direction at the correct amount each update.

- (void)rotateNode:(CCNode*)aNode degrees:(float)targetRotation withSpeed:(float)rotationSpeed withTimeDelta:(ccTime)dt
{
    rotationSpeed = rotationSpeed * dt;

    // Convert the difference between the two angles to radians
    float diff = (targetRotation - aNode.rotation) * (M_PI / 180);
    // Find the rotation of the vector created by the sin and cos of the difference
    float rotationDifference = atan2f(sinf(diff),cosf(diff));
    // Rotate the clip accordingly
    aNode.rotation += MAX(
                         MIN(
                             (180/M_PI) * rotationDifference,rotationSpeed), -rotationSpeed
                         );
}