src/3d/coordinates.lisp @ 8547dda4da61

(in-package #:coding-math.3d.coordinates)

;;; For this project, we'll define X and Y to be the typical 2D screen axes, and
;;; Z to be going into the screen (so it's a left-handed coordinate system).
;;;
;;; Cartesian coordinate vectors are:
;;;
;;;     (x y z)
;;;
;;; Cylindrical coordinate vectors are:
;;;
;;;     (radius azimuth height) where height is Y
;;;
;;; Polar coordinate vectors are:
;;;
;;;     TODO

(defun cylindrical-to-cartesian (coords)
  (with-vec3 (radius azimuth height) coords
    (make-vec3 (* radius (cos azimuth)) ; x
               height ; y
               (* radius (sin azimuth))))) ; z

(defun cartesian-to-cylindrical (coords)
  (with-vec3 (x y z) coords
    (make-vec3 (sqrt (+ (square x) (square z))) ; r
               (atan z x) ; a
               y))) ; h


(defmacro with-cga (bindings vec &body body)
  (once-only (vec)
    `(let ((,(first bindings) (aref ,vec 0))
           (,(second bindings) (aref ,vec 1))
           (,(third bindings) (aref ,vec 2)))
       ,@body)))

(defun cylindrical-to-cartesian-cga (coords)
  (with-cga (radius azimuth height) coords
    (sb-cga:vec (* radius (cos azimuth)) ; x
                height ; y
                (* radius (sin azimuth))))) ; z