2 files changed, 74 insertions, 0 deletions
diff --git a/src/gol.lisp b/src/gol.lisp
new file mode 100644
index 0000000..d954583
--- /dev/null
+++ b/src/gol.lisp
@@ -0,0 +1,71 @@
+(in-package #:gol)
+
+(asdf:load-systems :alexandria
+                   :sdl2)
+(use-package :alexandria)
+
+(deftype grid (width height)
+  `(array integer (,width ,height)))
+
+(defun next-generation (grid result)
+  (assert (equal (array-dimensions grid) (array-dimensions result)))
+  (destructuring-bind (m n) (array-dimensions grid)
+    (flet ((cell-value (i j)
+             (- (loop :for u :from (1- i) :repeat 3
+                    :summing
+                    (loop :for v :from (1- j) :repeat 3
+                          :summing (aref grid (mod u m) (mod v n))))
+                (aref grid i j))))
+      (dotimes (i m)
+        (dotimes (j n)
+          (let ((x (aref grid i j))
+                (y (cell-value i j)))
+            (setf (aref result i j)
+                  (if (zerop x)
+                      (if (= y 3) 1 0)
+                      (if (or (= y 2) (= y 3)) 1 0)))))))))
+
+(defun draw-grid (renderer grid &key (cell-w 10) (cell-h 10))
+  (destructuring-bind (m n) (array-dimensions grid)
+    (dotimes (i m)
+      (dotimes (j n)
+        (let ((rect (sdl2:make-rect (* i cell-h) (* j cell-w) cell-w cell-h)))
+          (sdl2:render-draw-rect renderer rect)
+          (unless (zerop (aref grid i j))
+            (sdl2:render-fill-rect renderer rect)))))))
+
+(defun run ()
+  (sdl2:with-init (:everything)
+    (sdl2:with-window (window)
+      (sdl2:with-renderer (renderer window)
+        (sdl2:with-event-loop ()
+          (:idle ()
+                 (sdl2:set-render-draw-color renderer 255 255 255 255)
+                 (sdl2:render-clear renderer)
+                 (sdl2:set-render-draw-color renderer 0 0 0 255)
+                 (draw-grid renderer *grid1*)
+                 (sdl2:render-present renderer)
+                 (sdl2:delay 200)
+                 (next-generation *grid1* *grid2*)
+                 (rotatef *grid1* *grid2*))
+          (:quit () t))))))
+
+
+(defparameter *grid1* (make-array '(20 20) :initial-element 0))
+(defparameter *grid2* (make-array '(20 20) :initial-element 0))
+
+(setf (aref *grid1* 0 0) 1
+      (aref *grid1* 1 0) 1
+      (aref *grid1* 1 1) 1
+      (aref *grid1* 2 1) 1
+      (aref *grid1* 0 2) 1)
+
+(run)
+
+*grid1*
+*grid2*
+
+(progn
+  (next-generation *grid1* *grid2*)
+  (rotatef *grid1* *grid2*)
+  *grid2*)
diff --git a/src/package.lisp b/src/package.lisp
new file mode 100644
index 0000000..1db28a2
--- /dev/null
+++ b/src/package.lisp
@@ -0,0 +1,3 @@
+(defpackage #:gol
+  (:use #:cl)
+  (:export))