XNA - Drawing zoomed 2D sprites

Question

I have a tile based game. Each tile texture is loaded and then I draw each one next to the other, forming a continuous background. I actually followed this tutorial for the xml files.

http://www.xnadevelopment.com/tutorials/looksleveltome/looksleveltome.shtml

The sources of the textures are 50x50.

However, it works only it the scale is 1 (or lower), if the scale is greater

The results : Normal size (50 pixel and scale 1) http://imageshack.us/photo/my-images/525/smallzp.jpg/

Larger size (Zoomed or 100 pixel in xml file) http://imageshack.us/photo/my-images/577/largeki.jpg/

We can see there are lines between the tiles, which are not in the texture. It's actually not so bad here, but in my game tileset, that's what it does : http://imageshack.us/photo/my-images/687/zoomedsize.png/

The same effect is present whether I increase the tile size in the xml file, change the scale when drawing or use my camera to zoom.

//zoom code
public Matrix GetTransformation()
{
    return
       Matrix.CreateTranslation(new Vector3(-_pos.X, -_pos.Y, 0)) *
       Matrix.CreateRotationZ(Rotation) *
       Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) *
       Matrix.CreateTranslation(new Vector3(_device.Viewport.Width * 0.5f, _device.Viewport.Height * 0.5f, 0));
}

//draw
_spriteBatch.Begin(SpriteSortMode.Immediate, 
  BlendState.AlphaBlend, null, null, null, null,
  _camera.GetTransformation());

//for each tile
theSpriteBatch.Draw(mSpriteTexture, Position, Source, 
  Color.Lerp(Color.White, Color.Transparent, mAlphaValue),
  mRotation, new Vector2(mSource.Width / 2, mSource.Height / 2),
  Scale, SpriteEffects.None, mDepth);

Is there a reason for this? A way to fix it to have a continuous texture when zoomed?

Answer 1

Use SamplerState.PointClamp to avoid the GPU interpolating texture coordinates with the nearest points.