Move and rotate a sprite using an accelerometer in SpriteKit

Question

I am trying to make my first game using Spritekit, so I have a sprite that I need to move using my accelerometer. Well, that is not a problem. the movement is really smooth and responsive, the problem is that when I try to rotate my sprite to make it collide with my own movement, I often “shake” it, as if it has parkinson. (: D)

I realized that this happens when the accelerometer data is too close to 0 on one of the x, y axes.

So the question is: is there a fix for my beloved Parkinson ?: D

Here is the code:

-(void) update:(NSTimeInterval)currentTime{
    static CGPoint oldVelocity;
    //static CGFloat oldAngle;

    if(_lastUpdatedTime) {
        _dt = currentTime - _lastUpdatedTime;
    } else {
        _dt = 0;
    }

    _lastUpdatedTime = currentTime;

    CGFloat updatedAccelX = self.motionManager.accelerometerData.acceleration.y;
    CGFloat updatedAccelY = -self.motionManager.accelerometerData.acceleration.x+sinf(M_PI/4.0);


    CGFloat angle = vectorAngle(CGPointMake(updatedAccelX, updatedAccelY));

    _velocity = cartesianFromPolarCoordinate(MAX_MOVE_PER_SEC, angle);


    if(oldVelocity.x != _velocity.x || oldVelocity.y != _velocity.y){
        _sprite.physicsBody.velocity = CGVectorMake(0, 0);
        [_sprite.physicsBody applyImpulse:CGVectorMake(_velocity.x*_sprite.physicsBody.mass, _velocity.y*_sprite.physicsBody.mass)];

        _sprite.zRotation = vectorAngle(_velocity);
        oldVelocity = _velocity;

    }
}

static inline CGFloat vectorAngle(CGPoint v){
    return atan2f(v.y, v.x);
}

_velocity , updatedAccelX updatedAccelY, >= , , , , 0,1 0,2, , 0,1.

, "" sprite.

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Answer 1

(., ) ( ).

    #define filteringFactor 0.1

    - (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {

        //low pass
        accelerX = (acceleration.x * filteringFactor) + (accelerX * (1.0 - filteringFactor));
        //idem …  accelerY
        //idem … accelerZ 

        //or high pass
        accelerX = acceleration.x - ( (acceleration.x * filteringFactor) + (accelerX * (1.0 - filteringFactor)) );
        //idem …  accelerY
        //idem … accelerZ
    }