title: Unity Tile with composed sprite
body: <p>I am trying to create a tile subclass for Unity's tilemap that would work similar to the RPG maker's <a href="http://blog.rpgmakerweb.com/tutorials/anatomy-of-an-autotile/" rel="nofollow noreferrer">autotile system</a>. Basic idea is that you provide your tile set in texture in the format below and it will join adjacent tiles of same type.</p>
  
  <p><a href="https://i.stack.imgur.com/Kkvgv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Kkvgv.png" alt="enter image description here"></a></p>
  
  <p>From this texture all the required tile layouts should be generated by matching 4 quarter squares together to create full tile. For example if I wanted to create an "L" shaped tile I would just reference 4 rects of quarters 16, 3, 20, 21.</p>
  
  <p>Is there a way I can create a single sprite that will reference that single template texture with multiple rects to form whole tile? Main choke point here is that the <a href="https://docs.unity3d.com/ScriptReference/Tilemaps.TileData.html" rel="nofollow noreferrer">TileData</a> takes only one sprite component.</p>
  
  <p>Can I maybe somehow split mesh of this sprite into 4 squares and set the uv's to reference correct quarters in texture?</p>