From 1b5440df2b7dc87c1088fc3842195dbd576276ff Mon Sep 17 00:00:00 2001
From: Colin Okay <colin@cicadas.surf>
Date: Wed, 20 Jul 2022 09:42:35 -0500
Subject: [example]

---
 examples/12-canvas-drawing-language.lisp | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/examples/12-canvas-drawing-language.lisp b/examples/12-canvas-drawing-language.lisp
index 24008c2..bece8c8 100644
--- a/examples/12-canvas-drawing-language.lisp
+++ b/examples/12-canvas-drawing-language.lisp
@@ -19,6 +19,7 @@
       (draw-stuff canvas)
       (ww::blit canvas)))
 
+;; draw a triangle, each side is a different color
 (defun triangle-at (x y)
   (ww::move-to x y)
   (ww::canvas-pen-color (list 0 200 200 255))
@@ -28,28 +29,39 @@
   (ww::canvas-pen-color (list 0 200 0 255))
   (ww::stroke-rel -100 -100))
 
+
+;; draw a filled triangle using the current pen
 (defun filled-triangle-at (x y)
   (ww::move-to x y)
   (ww::fill-rel-path
    '((100 100)
      (100 -100))))
 
+;; a pen function - gets more blue the closer x y is to 0 0
 (defun lower-the-bluer (x y)
   (list (* 256 (/ x 500))
         (* 256 (/ y 500))
         255
         255))
 
+;; a pen function - makes a plaid like pattern
 (defun plaid1 (x y)
   (list (mod (* x x) 256)
         (mod (* y y) 256)
         (mod (* x y) 256)
         255))
 
+;; draws a "flower" like pinwheel using bezier curves
 (defun flower (&optional (petals 5))
   (ww::canvas-pen-width 1)
-  (let ((r (sqrt (+ (* 25 25) (* 100 100))))
-        (psw (* pi 0.08))) 
+  (let ((r                              ; radius
+          (sqrt (+ (* 25 25) (* 100 100))))
+        (psw                            ; petal semi-width
+          (* pi 0.08))) 
+    ;; for each angle a between 0 and 2π draw a petal as a bezier
+    ;; curve.  the curve uses two control points that are R away from
+    ;; the starting point and PSW radians on either side of the line
+    ;; at angle a
     (loop for a from 0 to (* 2 pi) by (/ (* 2 pi) petals) do 
       (ww::stroke-rel-bezier
        (list (list (* r (sin (- a psw)))
@@ -61,17 +73,22 @@
 
 (defun draw-stuff (canvas)
   (ww::with-canvas canvas
+    ;; set canvas color. 
     (ww::canvas-pen-color #'plaid1)
     (filled-triangle-at 250 200)
-    (ww::canvas-pen-width 2)
 
-    ;; temporarily use a different pen
-    (ww::with-pen-color #'lower-the-bluer 
+    ;; temporarily use a different pen configuration
+    (ww::with-pen (:color #'lower-the-bluer :width 2) 
+      ;; draw a flower stem
       (ww::stroke-bezier
        '((0 0) (200 120) (50 350) (200 100) (300 400))
-       12))    ;; back to plaid pen after this
+       12)
+      ;; draw a flower
+      (flower 28)) 
+
+
 
-    (flower 28)
+    ;; draw a bunch of triangles
     (ww::canvas-pen-width 1)
     (dotimes (x 50)
       (when (evenp x)
-- 
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