#|
  This file is a part of stoe project.
  Copyright (c) 2015 Renaud Casenave-Péré (renaud@casenave-pere.fr)
|#

(uiop:define-package :stoe/maths/utils
    (:use :cl)
    (:export #:lerp #:clamp
             #:deg-to-rad #:rad-to-deg))
(in-package :stoe/maths/utils)

(defun lerp (a b ratio)
  "Linear interpolation of `a' and `b' based on `ratio'."
  (+ (* b ratio) (* a (- 1.0 ratio))))

(defun deg-to-rad (deg)
  "Convert an angle from degree to radian."
  (* deg (/ (* (coerce pi 'single-float) 2.0) 360.0)))

(defun rad-to-deg (rad)
  "Convert an angle from radian to degree."
  (/ rad (/ (* (coerce pi 'single-float) 2.0) 360.0)))

(defun clamp (number min max)
  "Clamp a `number' between `min' and `max'."
  (min max (max min number)))