anchor: SpriteBatch:attachAttribute
  Attaches a per-vertex attribute from a Mesh onto this SpriteBatch, for use when drawing. This can be combined with a Shader to augment a SpriteBatch with per-vertex or additional per-sprite information instead of just having per-sprite colors.
  
  Each sprite in a SpriteBatch has 4 vertices in the following order: top-left, bottom-left, top-right, bottom-right. The index returned by SpriteBatch:add (and used by SpriteBatch:set) can used to determine the first vertex of a specific sprite with the formula 1 + 4 * ( id - 1 ).
  SpriteBatch:attachAttribute( name, mesh )
  name string The name of the vertex attribute to attach.
  mesh Mesh The Mesh to get the vertex attribute from.