ex: 50.rkt: implement flip-horiz

2 files changed, 34 insertions, 0 deletions

diff --git a/ex/2/49.rkt b/ex/2/49.rkt
index 601d17c..989f36d 100644
--- a/ex/2/49.rkt
+++ b/ex/2/49.rkt
@@ -2,6 +2,11 @@
 
 #lang racket
 
+(provide
+ frame-coord-map
+ paint
+ wave->painter)
+
 (require racket/draw)
 (require racket/snip)
 
diff --git a/ex/2/50.rkt b/ex/2/50.rkt
new file mode 100644
index 0000000..d2b91a6
--- /dev/null
+++ b/ex/2/50.rkt
@@ -0,0 +1,29 @@
+;;;; License: CC0-1.0
+
+#lang racket
+
+(require "46.rkt")
+(require "47.rkt")
+(require "49.rkt")
+
+
+(define (transform-painter painter origin corner1 corner2)
+  (lambda (frame)
+    (let ((m (frame-coord-map frame)))
+      (let ((new-origin (m origin)))
+        (painter (make-frame
+                  new-origin
+                  (sub-vect (m corner1) new-origin)
+                  (sub-vect (m corner2) new-origin)))))))
+
+(define (flip-vert painter)
+  (transform-painter painter
+                     (make-vect 0.0 1.0)
+                     (make-vect 1.0 1.0)
+                     (make-vect 0.0 0.0)))
+
+(define (flip-horiz painter)
+  (transform-painter painter
+                     (make-vect 1.0 0.0)
+                     (make-vect 0.0 0.0)
+                     (make-vect 1.0 1.0)))