SpriteBatch.Draw in rectangle

Question

I want to make something like Terraria item sidebar thing. (the Left-top rectangles one). And here is my code.

Variables are

    public Rectangle InventorySlots;
    public Item[] Quickbar = new Item[9];
    public Item mouseItem = null;
    public Item[] Backpack = new Item[49];
    public int selectedBar = 0;

Here is the initialization

        inventory[0] = Content.Load<Texture2D>("Contents/Overlays/InventoryBG");
        inventory[1] = Content.Load<Texture2D>("Contents/Overlays/InventoryBG2");

update method

        int a = viewport.Width / 22;
        for (int b = 0; b <= Quickbar.Length; ++b)
        {
            InventorySlots = new Rectangle(((a/10)*b)+(b),0,a,a);
        }

draw method

            spriteBatch.Begin();
        for (int num = 0; num <= Quickbar.Length; ++num )
            spriteBatch.Draw(inventory[0], InventorySlots, Color.White);
        spriteBatch.Draw(inventory[1], InventorySlots, Color.White);
        spriteBatch.End();

Yes it is not done, but when i try to run it, the texture didn't show up. I am unable to find out what is wrong in my code.

is it in with SpriteBatch? In the draw method? or In the Update?

---

Resolved

The problem isnt at the code Itself. the Problem is in this:

        int a = viewport.Width / 22;

The thing is, i trought that viewport in here (I've used a Starter Kit) is the Game Window!

Answer 1

You are assigning InventorySlots overwriting its content... also it seems that you want to draw two sprites... but you are drawing only one inside the loop... and your looping over Quickbar when seems that its not related with your drawing calls.

And it seems that your slot layout calculations have few sense...

You should use an array or a list:

  public List<Rectangle> InventorySlots = new List<Rectangle>();


  // You put this code in update... but it's not going to change.. 
  // maybe initialize is best suited
  // Initialize
    int a = viewport.Width / 22; 
    InventorySlots.Clear();
    for (int b = 0; b < Quickbar.Length; ++b)
    {   // Generate slots in a line, with a pixel gap among them
        InventorySlots.Add( new Rectangle( 1 + (a+2) * b ,0,a,a) );
    }

    //Draw
    spriteBatch.Begin();
    for (int num = 0; num < InventorySlots.Count; ++num )
    {
        spriteBatch.Draw(inventory[0], InventorySlots[num], Color.White);
        spriteBatch.Draw(inventory[1], InventorySlots[num], Color.White);
    }
    spriteBatch.End();