2D Scrolling Background on XNA

Question

How do I create a scrolling X and scrolling Y background without weird things happening like the player disappearing or not getting the offset correct?

I have code at https://vanillity.kilnhg.com/Code/Repositories/Group/Aremac

Looks like this:

      var s = game.gd.Viewport.Bounds;
      var g = game.world.Bounds;
      var p = game.player.Bounds;
      var v = viewRectangle;

      var x = p.X  0 ? p.X - s.Width/2 :
              v.Right >= 1090 ?  90 :
              p.X > s.Width/2    ? p.X - s.Width/2 :
              0;


      var y = //v.Bottom > 
              p.Y > s.Height/2 ? p.Y - s.Height/2:
              0;

      var w = s.Width;
      var h = s.Height;

      //view Rectangle
      Offset        = new Vector2(x , y);
      viewRectangle = new Rectangle( x, y ,w, h);

and then:

     //source rectangle
     var x = (int)0;
     var y = (int)0;
     var g = game.world.Bounds;
     var w = g.Width;
     var h = g.Height;
     var rect =  new Rectangle(x,y,w,h);


      spriteBatch.Draw(  w.boundsTexture 
                        ,rect
                        ,viewRectangle                                 
                        ,w.Color
                        ,0
                        ,Vector2.Zero
                        ,SpriteEffects.None
                        ,1
                        ); 

Before center, the grey guy is holding the rock in his left hand:

After center, the rock (and the white guy) drifts evermore to the right:

Answer 1

Rewrite this statement in a more readable fashion:

var x = p.X > v.Width     ? p.X - v.X/2: 
          p.X > s.Width/2   ? p.X - s.Width/2 :
          0;

And your problem is solved.

if p.X > v.Width then
    x = p.x - v.x/2;
else
    if p.x > s.width/2 then
        x = p.x - s.width/2;
    else 
        x=0;

Also, your viewRect should never have it's width or height changing. You seem to be trying to over complicate things.

You need a viewport offset for X and Y. You need a player position. The viewport offset is p.offset - viewport.size / 2 The viewport has a size.

You then want to draw from viewport offset (maybe - 1) to viewport offset + viewport size.