   Pixel Shader Edges/Bounds Question
  I wrote a simple pixel shader (2.0) to draw an outline around an image. I've noticed if I make the outline large where it extends past the border of the image I am drawing it cuts off at the edge of the image despite the screen being larger.  (Example of a potato: http://img16.imageshack.us/img16/3682/25314401.png see how it cuts off?)I'm trying to implement a simple workaround for this, as I'm also trying to apply this shader to XNA's SpriteBatch.DrawString method, what I would like to do ideally is extend the bounds of the "drawable" area, the only solution I've been able to think of would be to rescale the image within the shader, and then apply the border, however this would cause inconsistencies with the size of the image when the border was not applied. Any help or direction would be appreciated.   
  Pixels will only be shaded where triangles are drawn. You can't change anything like that in the pixel shader. In the case of a sprite, what you can try to do is, in your vertex shader, the scale the vertices so that they're a little bigger and change the texture coordinates so that they're less than 0 or greater than 1.   