timsg.scene-var

An Arcadia library for interacting with the Unity scene graph.

Clojars

[timsg.scene-var "0.1.0-SNAPSHOT"]

Usage

defgetter defines getter functions for constructing, mutating, and retrieving individual GameObjects from the Unity scene graph.

Syntax: (defgetter name 0-ary-body? 1-ary-body?)

It establishes and maintains a live, serializable correspondence between the var named by name and an individual GameObject, and binds this var to a 0-ary getter function instance that will always return the currently-corresponding GameObject.

The syntax is close to that of a defn, with bodies of 0 or 1 arguments supplied:

(defgetter the-floor
  ([]
   (let [floor (arcadia.core/create-primitive :cube)]
     (set! (.name floor) "the-floor")
     floor))
  ([floor]
   (arcadia.core/with-cmpt floor [tr Transform]
     (set! (.position tr) (v3 0 -0.5 0))
     (set! (.localScale tr) (v3 1000 1 100)))))

Then:

(the-floor)
;; => the floor GameObject

Both arities only run when the defgetter form itself is evaluated (they are not the body of the produced getter function).

The 0-ary body is useful for constructing GameObject, the 1-ary body is body is useful for mutating existing GameObjects or changing the association to a different GameObject.

0-ary body

([] exprs*)

The 0-ary body, if supplied, runs only if the var bound by this def form (#'car, in the example above) is currently not associated with a live GameObject, and should return a GameObject (an error is thrown if it does not). The var will then be associated with the returned GameObject. This arity can be used to create a new GameObject, or to find one already in the scene.

1-ary body

([obj] exprs*)

The 1-ary body, if supplied, runs whenever the defgetter form is evaluated (just after the 0-ary body, if it is present). obj is the GameObject currently associated with the var, or nil if no such var exists.

If the 1-ary body returns a GameObject, the var will be associated with that GameObject. If it does not, or if an error is thrown in exprs*, the var will remain associated with obj.

After defgetter is evaluated, the var name will be bound to a getter function that will return the GameObject associated with name, or nil if no such GameObject exists. If the GameObject associated with name changes, the getter function will subsequently return that new GameObject.

License

Copyright © 2016 Tims Gardner

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.