Windows Phone加速度计的困难

Question

I want to use the accelerometer to move a ball in a Windows Phone game. But the ball moves not correct when I tilt the Windows Phone device.

For example, if I tilt the device to the left, the ball isn't moving to the left, instead the ball moves very strange. I don't know what I could change in my code so that the ball moves correctly.

What should I change so that the ball moves correctly if I tilt the Windows Phone device?

UPDATE: I changed my code but the ball doesn't move in the right direction. You can download my project here: http://www.file-upload.net/download-8439759/WindowsPhoneGame22.rar.html

public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;
    Motion motion;
    Texture2D Ball;
    Vector2 BallPos = new Vector2(400, 300);
    Vector3 accelReading = new Vector3();
    Vector3 speed = new Vector3();

    void motion_CurrentValueChanged(object sender, SensorReadingEventArgs<MotionReading> e)
    {
        UpdateUI(e.SensorReading);
    }

    private void UpdateUI(MotionReading e)
    {
        accelReading.X = e.DeviceAcceleration.X;
        accelReading.Y = e.DeviceAcceleration.Y;
        accelReading.Z = e.DeviceAcceleration.Z;
        accelReading.Normalize();

        Vector3 currentAccelerometerState = accelReading;
        if (currentAccelerometerState.X != 0)
            speed += new Vector3(currentAccelerometerState.X, 0, 0);
        if (currentAccelerometerState.Z != 0)
            speed += new Vector3(0, 0, -currentAccelerometerState.Z);

        if (speed.Length() > 2)
        {
            speed.Normalize();
            speed *= 2;
        }

        BallPos.X += speed.X;
        BallPos.Y += speed.Y;
    }

    public Game1()
    {
        graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
        TargetElapsedTime = TimeSpan.FromTicks(333333);
        InactiveSleepTime = TimeSpan.FromSeconds(1);
        graphics.IsFullScreen = true;
    }

    protected override void Initialize()
    {
        if (Motion.IsSupported)
        {
            motion = new Motion();
            motion.TimeBetweenUpdates = TimeSpan.FromMilliseconds(20);
            motion.CurrentValueChanged += new EventHandler<SensorReadingEventArgs<MotionReading>>(motion_CurrentValueChanged);
            motion.Start();
        }

        base.Initialize();
    }


    protected override void LoadContent()
    {
        spriteBatch = new SpriteBatch(GraphicsDevice);
        Ball = Content.Load<Texture2D>("ballbig");
    }

    protected override void Update(GameTime gameTime)
    {

        base.Update(gameTime);
    }

    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);

        spriteBatch.Begin();
          spriteBatch.Draw(Ball, BallPos, null, Color.White, rotation, new Vector2(Ball.Width/2,Ball.Height/2), 1f, SpriteEffects.None,1);
        spriteBatch.End();

        base.Draw(gameTime);
    }
}

Answer 1

I did a pretty similar game on Windows8, and I use a method like this to handle the accelerometer. I hope you can find something that can help you.

private Accelerometer _accelerometer;

public void Initialize()
{
    if (_accelerometer != null)
    {
        _accelerometer = Accelerometer.GetDefault();
        _accelerometer.ReadingChanged += _accelerometer_ReadingChanged;
    }
}

private void _accelerometer_ReadingChanged(Accelerometer sender, AccelerometerReadingChangedEventArgs args)
{
    AccelerometerReading reading = _accelerometer.GetCurrentReading();
    Vector3 stateValue = new Vector3();
    stateValue.Y = -1;
    stateValue.X = (float)reading.AccelerationX;
    stateValue.Z = (float)reading.AccelerationY;
    stateValue.Normalize();

    Vector3 currentAccelerometerState = stateValue;
    Vector3 Rotation = Vector3.Zero;
    if (currentAccelerometerState.X != 0)
        marble.speed += new Vector3(currentAccelerometerState.X, 0, 0);
    if (currentAccelerometerState.Z != 0)
        marble.speed += new Vector3(0, 0, -currentAccelerometerState.Z);

    if (marble.speed.Length() > 10)
    {
        marble.speed.Normalize();
        marble.speed *= 10;
    }
}