===== Referencing External 3D Models =====

GroIMP allows the reuse of external 3D models (e.g., ``.dtd`` files created in the RGG editor) by referencing them directly in XL code. This is done using the ``Reference(...)`` constructor.

==== Basic Usage ====

To instantiate a 3D object into the scene:

  Reference("cherry_new.dtd");

This creates a single node representing the geometry of the external object but does not import its internal graph structure.

==== Example: Multiple Instances ====

This example creates three identical tree models placed along the y-axis:

  protected void init()
  [
    Axiom ==> for(int i=0; i<3; i++)(
      Translate(0, 1, 0)
      [
        Reference("cherry_new.dtd");
      ]
    );
  ]