private void DrawGround()
        {
            //draw the tile texture tiles across the screen
            Rectangle source = new Rectangle(0, 0, GraphicsDevice.Viewport.Width, GraphicsDevice.Viewport.Height);
            spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.Opaque, SamplerState.LinearWrap, DepthStencilState.Default, RasterizerState.CullNone);
            spriteBatch.Draw(tileTexture, Vector2.Zero, source, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 1.0f);
            spriteBatch.End();

        }