675cba1dba01

--- a/coding-math.asd	Tue May 10 23:59:15 2016 +0000
+++ b/coding-math.asd	Wed May 11 00:24:58 2016 +0000
@@ -35,5 +35,6 @@
                  (:module "3d"
                   :serial t
                   :components ((:file "vectors")
+                               (:file "coordinates")
                                (:file "demo")))))))
 

--- a/package.lisp	Tue May 10 23:59:15 2016 +0000
+++ b/package.lisp	Wed May 11 00:24:58 2016 +0000
@@ -207,6 +207,18 @@
     #:with-vec3
     #:with-vec3s))
 
+(defpackage #:coding-math.3d.coordinates
+  (:use
+    #:cl
+    #:coding-math.math
+    #:coding-math.3d.vectors
+    #:coding-math.utils
+    #:coding-math.quickutils)
+  (:export
+    #:cartesian-to-cylindrical
+    #:cylindrical-to-cartesian
+    ))
+
 (defpackage #:coding-math.3d.demo
   (:use
     #:cl
@@ -216,5 +228,6 @@
     #:coding-math.fps
     #:coding-math.math
     #:coding-math.3d.vectors
+    #:coding-math.3d.coordinates
     ))
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/3d/coordinates.lisp	Wed May 11 00:24:58 2016 +0000
@@ -0,0 +1,29 @@
+(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
+