Scaling problems in XNA - xna

Question

Here's the thing. I'm in a team where we're trying to develop a Asteroid like game and my part of the game was everything related to images. I understood everything, but scaling. My problem is that when I scale the image it slightly moves from the position that was originally assign. But, I want it to stay in the same place when it's been scaled. Tried replacing vectors with rectangles and it didn't work. Here's my code:
public class Game1 : Microsoft.Xna.Framework.Game
{
Texture2D texture;
Vector2 position = new Vector2(525, 325);
float scale = 0.3f;
Texture2D texture2;
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
// Frame rate is 30 fps by default for Windows Phone.
TargetElapsedTime = TimeSpan.FromTicks(333333);
// Extend battery life under lock.
InactiveSleepTime = TimeSpan.FromSeconds(1);
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
// TODO: Add your initialization logic here
base.Initialize();
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
texture = Content.Load<Texture2D>("Spacenebula_Backround_");
texture2 = Content.Load<Texture2D>("PressureSphere");
// TODO: use this.Content to load your game content here
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// all content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <summary>
/// Allows the game to run logic such as updating the world,
/// checking for collisions, gathering input, and playing audio.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Update(GameTime gameTime)
{
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
// TODO: Add your update logic here
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
spriteBatch.Begin();
spriteBatch.Draw(texture, Vector2.Zero, Color.Wheat);
spriteBatch.Draw(texture2,position, null, Color.Wheat, 0, new Vector2(0, 0), scale, SpriteEffects.None, 0);
spriteBatch.End();
// TODO: Add your drawing code here
base.Draw(gameTime);
}
} }
the smallest scale is 0.3f and the largest 1.3f.
When the scale is at 0.3f looks like this :
When the scale is at 1.3f looks like this:
see what I mean? I need it to be at the same position every time the scale is changed. I would gladly appreciate if anyone helps me.

Answer 1

As part of the spriteBatch.Draw method, you specify the origin of the image. ("new Vector(0,0)")
Currently, you appear to be setting it as the top left corner of the image which means any scaling efforts are going to "grow" from the top left of the image as well.
Try setting the origin to the center of your image(s) instead.
This will ensure the image gets scaled correctly without it appearing to move / get displaced by scaling.

Answer 2

If you are using collision detection, make sure you also use scale parameter into calculation. Height and width of sprite is still same, no matter how you scale it. as well change radius if using circle collision.