;;-*-Lisp-*-
(in-package goal)

;; name: lights.gc
;; name in dgo: lights
;; dgos: GAME, ENGINE

(defun light-slerp ((out light) (a light) (b light) (alpha float))
  "Linearly interpolate between two light's vectors. Alpha is clamped between 0 - 1."

  (let ((clamped-alpha (fmax 0.0 (fmin 1.0 alpha))))
   (vector-lerp! (-> out color) (-> a color) (-> b color) clamped-alpha)
   (vector-deg-slerp
    (-> out direction)
    (-> a direction)
    (-> b direction)
    clamped-alpha
    )
   (let ((f0-2 (-> a levels x))
         (f1-2 (-> b levels x))
         )
    (set! (-> out levels x) (+ f0-2 (* clamped-alpha (- f1-2 f0-2))))
    )
   )
  out
  )

(defun light-group-slerp ((out light-group) (a light-group) (b light-group) (alpha float))
  "Linearly interpolate between each of the 4 vectors of two light-groups.
   Alpha is clamped between 0 - 1."

  (dotimes (vec-index 4)
   (light-slerp
    (-> out lights vec-index)
    (-> a lights vec-index)
    (-> b lights vec-index)
    alpha
    )
   )
  out
  )

(defun light-group-process! ((arg0 vu-lights) (arg1 light-group) (arg2 vector) (arg3 vector))
  (rotate-y<-vector+vector arg3 arg2)
  (vu-lights<-light-group! arg0 arg1)
  (none)
  )

(define *default-lights* (new 'global 'vu-lights))

(defun vu-lights-default! ((lights vu-lights))
  "Initialize a lights object with default values"

  (set-vector! (-> lights ambient) 0.3 0.3 0.3 1.0)

  (set-vector! (-> lights color 0) 1.0 1.0 1.0 1.0)
  (set-vector! (-> lights color 1) 0.2 0.2 0.2 1.0)
  (set-vector! (-> lights color 2) 0.0 0.0 0.0 1.0)

  (set-vector! (-> lights direction 0) 1.0 0.0 0.0 1.0)
  (set-vector! (-> lights direction 1) 0.0 1.0 0.0 1.0)
  (set-vector! (-> lights direction 2) 0.0 0.0 1.0 1.0)

  lights
  )