Why isn't my sprite being drawn in the correct position in XNA?

Question

Sorry if this has been asked before, but I can't seem to find it here. I'm trying to make an asteroids clone in XNA. I took the Game State Management project and am making new classes for things like the player and placing them in the GameplayScreen class. For some reason my ship isn't being draw correctly.

GameplayScreen's Draw method:

 public override void Draw(GameTime gameTime)
    {
        ScreenManager.GraphicsDevice.Clear(ClearOptions.Target,
                                           Color.CornflowerBlue, 0, 0);

        SpriteBatch spriteBatch = ScreenManager.SpriteBatch;

        spriteBatch.Begin();
        //draw fps
        if(showFPS)
            spriteBatch.DrawString(framerateFont, "FPS: " + frameRate, new Vector2(15, 15), Color.White);


        player.Draw(spriteBatch);

        spriteBatch.End();

        // If the game is transitioning on or off, fade it out to black.
        if (TransitionPosition > 0 || pauseAlpha > 0)
        {
            float alpha = MathHelper.Lerp(1f - TransitionAlpha, 1f, pauseAlpha / 2);

            ScreenManager.FadeBackBufferToBlack(alpha);
        }
    }

And my ship's drawing code:

 public PlayerShip(Game game)
    {
        this.game = game;
        Viewport view = game.GraphicsDevice.Viewport;
        center = new Vector2(view.Width / 2, view.Height /2);
        sourceRectangle = new Rectangle();
        Reset(center);
    }

    public void Reset(Vector2 position)
    {
        this.position = position;
    }

    public void LoadContent()
    {
        ship = game.Content.Load<Texture2D>("ship");
        sourceRectangle = new Rectangle(0, 0, ship.Width,
            ship.Height);
        origin = new Vector2(ship.Width / 2, ship.Height);
    }

    public void Update(GameTime gameTime)
    {
        HandleInput();

    }

    //handles all keyboard input by user. rotates ship based on current rotation.
    private void HandleInput()
    {
        input = Keyboard.GetState();
        float x = position.X;
        float y = position.Y;
        Matrix m = Matrix.CreateRotationZ(rotation);

        if (input.IsKeyDown(Keys.Right))
            rotation += turnFactor;
        else if (input.IsKeyDown(Keys.Left))
            rotation -= turnFactor;
        else if (input.IsKeyDown(Keys.Up))
        {
            x += m.M12 * directionFactor;
            y -= m.M11 * directionFactor;
        }
        else if (input.IsKeyDown(Keys.Down))
        {
            x -= m.M12 * directionFactor;
            y += m.M11 * directionFactor;
        }
        position.X = x;
        position.Y = y;
        Console.WriteLine("Y: {0} ", y);
        Console.WriteLine("X: {0} ", x);
    }

    public void Draw(SpriteBatch sb)
    {
        Vector2 origin = new Vector2(ship.Width / 2, ship.Height);
        sb.Draw(ship, ship.Bounds, null, Color.White, rotation, origin, SpriteEffects.None, 0f);
    }

I hooked the project up to a console window and it seems that the X and Y positions are updating correctly code wise, but not visually. It seems to update where it is rotationally, but going up or down doesn't draw correctly.

Image of what it's doing http://imgur.com/4cKBk

Answer 1

The problem is that when you're using the following version of SpriteBatch.Draw:

public void Draw (
     Texture2D texture,
     Rectangle destinationRectangle,         // Destination rectangle on _screen_
     Nullable<Rectangle> sourceRectangle,
     Color color,
     float rotation,
     Vector2 origin,
     SpriteEffects effects,
     float layerDepth
)

And calling it with the following parameters:

// Wrong version
sb.Draw(ship, ship.Bounds, null, Color.White, rotation, origin, SpriteEffects.None, 0f);

The second parameter is expecting the destinationRectangle where the sprite should be drawn on screen but you're passing it the sprite's ship.Bounds which is simply a Rectangle like (0, 0, ship.Width, ship.Height). That's why the sprite is always stuck to the corner of the screen.

This is a simple fix. Just change that line to:

// Correct version
sb.Draw(ship, position, null, Color.White, rotation, origin, 1f, SpriteEffects.None, 0f);

And if everything else is correct, it should work. That's just another version of SpriteBatch.Draw that goes like this:

public void Draw (
     Texture2D texture,
     Vector2 position,
     Nullable<Rectangle> sourceRectangle,
     Color color,
     float rotation,
     Vector2 origin,
     float scale,
     SpriteEffects effects,
     float layerDepth
)