public void onSensorChanged(SensorEvent event) {
        int sensorType = event.sensor.getType();
        switch (sensorType){
            case Sensor.TYPE_ROTATION_VECTOR:

                SensorManager.getRotationMatrixFromVector(rMat,event.values);
                compass = Math.round( (int) (Math.toDegrees(SensorManager.getOrientation(rMat,orientation)[0]) + 360) % 360);

                if (initialCompass < 0){
                    initialCompass = compass;
                }

                compassDiff = compass - initialCompass;
                System.out.println(compassDiff);

                Log.d(TAG, "Compassdiff: "+ compassDiff);
                Log.d(TAG, "InitialCompass: "+ initialCompass);
                Log.d(TAG, "Compass: "+ compass);

                // Down
                if (inRange(compassDiff, 137, 223) || inRange(compassDiff, -223, -137)){
                    final Animation animation = createAnimation();
                    final ImageButton btnDown = findViewById(R.id.imageDown);
                    btnDown.startAnimation(animation);
                    btnDown.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(final View view) {
                            view.clearAnimation();
                        }
                    });

                    initialCompass += 180;
                    if (initialCompass >= 360){
                        initialCompass -= 360;
                    }
                }

                // Right
                else if (inRange(compassDiff, 47, 133) || inRange(compassDiff, -313, -227)){
                    Log.d(TAG, "right entered");
                    final Animation animation = createAnimation();
                    final ImageButton btnRight = findViewById(R.id.imageRight);
                    btnRight.startAnimation(animation);
                    btnRight.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(final View view) {
                            view.clearAnimation();
                        }
                    });

                    initialCompass += 90;
                    if (initialCompass >= 360){
                        initialCompass -= 360;
                    }
                }

                // Left
                else if (inRange(compassDiff, -133, -47) || inRange(compassDiff, 227, 313)){
                    Log.d(TAG, "left entered");
                    final Animation animation = createAnimation();
                    final ImageButton btnLeft = findViewById(R.id.imageLeft);
                    btnLeft.startAnimation(animation);
                    btnLeft.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(final View view) {
                            view.clearAnimation();
                        }
                    });

                    initialCompass -= 90;
                    if (initialCompass < 0){
                        initialCompass += 360;
                    }
                }

                // Up
                else if ((compassDiff >= -43) || (compassDiff <= 43)){
                    Log.d(TAG, "up entered");
                    final Animation animation = createAnimation();
                    final ImageButton btnUp = findViewById(R.id.imageUp);
                    btnUp.startAnimation(animation);
                    btnUp.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(final View view) {
                            view.clearAnimation();
                        }
                    });
                }

                break;

                default :
                    break;
        }
    }

    private Animation createAnimation() {
        // Change alpha from fully visible to invisible
        final Animation animation = new AlphaAnimation(1, 0);
        // duration is set to half a second
        animation.setDuration(500);
        // Do not alter animation rate
        animation.setInterpolator(new LinearInterpolator());
        // Repeat animation infinitely
        animation.setRepeatCount(3);
        // Reverse animation at the end so the button will fade back in
        animation.setRepeatMode(Animation.REVERSE);
        return animation;
    }

    // checks if compass difference is in range of const1 and const2
    private Boolean inRange(float x, float const1, float const2) {
        return x >= const1 && x <= const2;
    }