vec2.clj

(ns vector-math.core
  (:import [javax.vecmath Vector2d]))

(def epsilon 1e-6)

(defprotocol Vec2Math
  (add [this other])
  (sub [this other])
  (mul [this scalar])
  (div [this scalar])
  (clean [this])
  (unit [this])
  (length-squared [this])
  (dot-product [this]))

(deftype vec2
  [#^float x #^float y] :as this
  Vec2Math 
  (add [other] (vec2. (+ x (.x #^vec2 other))
                      (+ y (.y #^vec2 other))))
  (sub [other] (vec2. (- x (.x #^vec2 other))
                      (- y (.y #^vec2 other))))
  (mul [scalar] (let [scalar (float scalar)]
                  (vec2. (* x scalar)
                         (* y scalar))))
  (div [scalar] (let [scalar (float scalar)]
                  (vec2. (/ x scalar)
                         (/ y scalar))))
  (length-squared [] (+ (* x x) (* y y))))

(def v (vec2 5.0 2.0))
(length-squared v)

;; ^ the line above throws the following exception:
;; vector-math.core.vec2__3954.length_squared()Ljava/lang/Object;
;;  [Thrown class java.lang.AbstractMethodError]