StaticGraphicsObject

using UnityEngine;
using System.Collections;

public class StaticGraphicsObject : MonoBehaviour
{
    public string GraphicsPath;
    public int GraphicsIndex;

    private SpriteRenderer _renderer;

    public void OnEnable()
    {
        _renderer = GetComponent<SpriteRenderer>();

        GetGraphicsLayerDepth();

        UpdateGraphic();
    }

    public void GetGraphicsLayerDepth()
    {
        bool gotDepth = false;

        GameObject currentGameObject = gameObject;

        do
        {
            currentGameObject = currentGameObject.GetParent();

            if (currentGameObject == null)
                break;

            if (currentGameObject.tag == "Graphics Layer")
            {
                GraphicsLayer graphicsLayer = currentGameObject.GetComponent<GraphicsLayer>();
                gotDepth = true;
                _renderer.sortingLayerName = string.Format("Graphics Layer " + graphicsLayer.Depth);
            }
        }
        while (!gotDepth);
    }

    public void UpdateGraphic()
    {
        // Ensure we have a renderer (Used in the editor)
        if (Application.isEditor)
        {
            _renderer = gameObject.GetComponent<SpriteRenderer>();
            GetGraphicsLayerDepth();
        }

        // Get the sprite sheet
        Sprite[] spriteSheet = Resources.LoadAll<Sprite>(GraphicsPath);

        // Check for no sprites found
        if (spriteSheet.Length == 0)
            return;

        // Wrap around if longer than the number of sprites in the sprite sheet
        if (GraphicsIndex < 0)
            GraphicsIndex = spriteSheet.Length - 1;
        GraphicsIndex %= spriteSheet.Length;

        // Update the graphic
        _renderer.sprite = spriteSheet[GraphicsIndex];
    }
}