9 files changed, 661 insertions, 0 deletions
diff --git a/chapter5/guess.rkt b/chapter5/guess.rkt
new file mode 100644
index 0000000..f7a117a
--- /dev/null
+++ b/chapter5/guess.rkt
@@ -0,0 +1,75 @@
+#lang racket
+(require 2htdp/universe 2htdp/image)
+
+(struct interval (small big guesses))
+
+;;; constants
+(define TEXT-SIZE 12)
+(define HELP-TEXT
+  (text "↑ for larger numbers, ↓ for smaller ones"
+        TEXT-SIZE
+        "blue"))
+(define HELP-TEXT2
+  (text "Press = when your number is guessed; q to quit."
+        TEXT-SIZE
+        "blue"))
+(define COLOR "red")
+(define WIDTH (+ (image-width HELP-TEXT2) 10))
+(define HEIGHT 150)
+(define SIZE 72)
+(define TEXT-X 3)
+(define TEXT-UPPER-Y 10)
+(define TEXT-LOWER-Y 135)
+(define GUESSES-SIZE 12)
+(define GUESSES-COLOR "green")
+(define MT-SC
+  (place-image/align
+   HELP-TEXT TEXT-X TEXT-UPPER-Y "left" "top"
+   (place-image/align
+    HELP-TEXT2 TEXT-X TEXT-LOWER-Y "left" "bottom"
+    (empty-scene WIDTH HEIGHT))))
+
+;; main
+(define (start lower upper)
+  (big-bang (interval lower upper 0)
+            (on-key deal-with-guess)
+            (to-draw render)
+            (stop-when single? render-last-scene)))
+
+;; key events
+(define (deal-with-guess w key)
+  (cond [(key=? key "up") (bigger w)]
+        [(key=? key "down") (smaller w)]
+        [(key=? key "q") (stop-with w)]
+        [(key=? key "=") (stop-with w)]
+        [else w]))
+
+(define (smaller w)
+  (interval (interval-small w)
+            (max (interval-small w) (sub1 (guess w)))
+            (+ 1 (interval-guesses w))))
+
+(define (bigger w)
+  (interval (min (interval-big w) (add1 (guess w)))
+            (interval-big w)
+            (+ 1 (interval-guesses w))))
+
+(define (guess w)
+  (quotient (+ (interval-small w) (interval-big w)) 2))
+
+(define (render w)
+  (overlay (overlay/offset
+            (text (number->string (guess w)) SIZE COLOR) 0 40
+            (text (number->string (interval-guesses w))
+                  GUESSES-SIZE GUESSES-COLOR))
+           MT-SC))
+
+(define (render-last-scene w)
+  (overlay (overlay/offset
+            (text "End" SIZE COLOR) 0 40
+            (text (number->string (interval-guesses w))
+                  GUESSES-SIZE GUESSES-COLOR))
+           MT-SC))
+
+(define (single? w)
+  (= (interval-small w) (interval-big w)))
diff --git a/chapter5/loco.rkt b/chapter5/loco.rkt
new file mode 100644
index 0000000..977c976
--- /dev/null
+++ b/chapter5/loco.rkt
@@ -0,0 +1,59 @@
+#lang racket
+(require 2htdp/universe 2htdp/image)
+
+(define WIDTH 300)
+(define HEIGHT 300)
+(define CAROILLE (bitmap/file "resources/caroille.png"))
+(define CAROILLE-WIDTH (image-width CAROILLE))
+
+;;;
+;;; If the car is placed at X = 1/2 its width, its back will be
+;;; touching the left edge of the World.
+;;;
+;;; If the car is place at X = - 1/2 its width, its front will be touching
+;;; the left edge of the World.
+;;;
+(define CAROILLE-WIDTH-HALF (/ CAROILLE-WIDTH 2.0))
+
+;;; Structure to represent the X position of two cars in animation.
+(struct cars (one two))
+
+(define (caroille-past-right-edge? pos)
+  (> pos (- WIDTH CAROILLE-WIDTH-HALF)))
+
+(define (caroille-fully-past-right-edge? pos)
+  (>= pos (+ WIDTH CAROILLE-WIDTH-HALF)))
+
+(define (caroille-fully-past-left-edge? pos)
+  (>= pos CAROILLE-WIDTH-HALF))
+
+(define (caroille-fully-inside? pos)
+  (and (caroille-fully-past-left-edge? pos)
+       (not (caroille-past-right-edge? pos))))
+
+(define (move caroilles)
+  (let ((caroille-one (cars-one caroilles))
+        (caroille-two (cars-two caroilles)))
+    (cond
+      ;; Case set I - one of the cars is fully inside.
+      ((caroille-fully-inside? caroille-one)
+       (cars (+ 1 caroille-one) caroille-two))
+      ((caroille-fully-inside? caroille-two)
+       (cars caroille-one (+ 1 caroille-two)))
+      ;; Case set II - one of the cars disappeared into the right edge.
+      ((caroille-fully-past-right-edge? caroille-one)
+       (cars (- CAROILLE-WIDTH-HALF) (+ 1 caroille-two)))
+      ((caroille-fully-past-right-edge? caroille-two)
+       (cars (+ 1 caroille-one) (- CAROILLE-WIDTH-HALF)))
+      ;; Case else - Both cars are partially out.
+      (else (cars (+ 1 caroille-one) (+ 1 caroille-two))))))
+
+(define (draw-cars caroilles)
+  (place-image CAROILLE (cars-one caroilles) (/ HEIGHT 2)
+               (place-image CAROILLE (cars-two caroilles) (/ HEIGHT 2)
+                            (empty-scene WIDTH HEIGHT))))
+
+(define (start)
+  (big-bang (cars CAROILLE-WIDTH-HALF (- CAROILLE-WIDTH-HALF))
+            (on-tick move)
+            (to-draw draw-cars)))
diff --git a/chapter5/resources/caroille.png b/chapter5/resources/caroille.png
new file mode 100644
index 0000000..052cc58
--- /dev/null
+++ b/chapter5/resources/caroille.png
diff --git a/chapter5/resources/caroille.svg b/chapter5/resources/caroille.svg
new file mode 100644
index 0000000..eb4db63
--- /dev/null
+++ b/chapter5/resources/caroille.svg
@@ -0,0 +1,125 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
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+        <dc:title>caroille</dc:title>
+        <cc:license
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+        <dc:date>2018-04-02</dc:date>
+        <dc:creator>
+          <cc:Agent>
+            <dc:title>rsiddharth &lt;s@ricketyspace.net&gt;</dc:title>
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+        </dc:creator>
+        <dc:subject>
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diff --git a/chapter5/resources/ufo-fart.png b/chapter5/resources/ufo-fart.png
new file mode 100644
index 0000000..13d1c4a
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+++ b/chapter5/resources/ufo-fart.png
diff --git a/chapter5/resources/ufo-fart.svg b/chapter5/resources/ufo-fart.svg
new file mode 100644
index 0000000..cf86021
--- /dev/null
+++ b/chapter5/resources/ufo-fart.svg
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+<!-- Created with Inkscape (http://www.inkscape.org/) -->
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+<svg
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+        <dc:title>UFO Fart</dc:title>
+        <cc:license
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+        <dc:date>2018-04-17</dc:date>
+        <dc:creator>
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diff --git a/chapter5/resources/zarking-ufo.png b/chapter5/resources/zarking-ufo.png
new file mode 100644
index 0000000..bd5eb43
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diff --git a/chapter5/resources/zarking-ufo.svg b/chapter5/resources/zarking-ufo.svg
new file mode 100644
index 0000000..84b8844
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diff --git a/chapter5/ufo.rkt b/chapter5/ufo.rkt
new file mode 100644
index 0000000..6f8136c
--- /dev/null
+++ b/chapter5/ufo.rkt
@@ -0,0 +1,86 @@
+#lang racket
+(require 2htdp/universe 2htdp/image)
+
+;;; world structure
+(struct ufo (x y fart))
+
+;;; constants
+(define WORLD-WIDTH 300)
+(define WORLD-HEIGHT 325)
+(define MOVE-LEN 3)
+(define UFO (bitmap/file "resources/zarking-ufo.png"))
+(define UFO-FART (bitmap/file "resources/ufo-fart.png"))
+(define UFO-WIDTH (image-width UFO))
+(define UFO-HEIGHT (image-height UFO))
+(define UFO-FART-HEIGHT (image-height UFO-FART))
+
+;;; ufo movement functions
+(define (ufo-move-up current-state)
+  (let ((x (ufo-x current-state))
+        (y-up (- (ufo-y current-state) MOVE-LEN))
+        (fart #t))
+    (cond [(>= y-up (+ (/ UFO-HEIGHT 2) (/ UFO-FART-HEIGHT 2)))
+           (ufo x y-up fart)]
+          [else current-state])))
+
+(define (ufo-move-down current-state)
+  (let ((x (ufo-x current-state))
+        (y-down (+ (ufo-y current-state) MOVE-LEN)))
+    (cond [(<= y-down (- (+ WORLD-HEIGHT (/ UFO-FART-HEIGHT 2))
+                         (/ UFO-HEIGHT 2)))
+           (ufo x y-down #t)]
+          [else current-state])))
+
+
+(define (ufo-move-left current-state)
+  (let ((x-left (- (ufo-x current-state) MOVE-LEN))
+        (y (ufo-y current-state))
+        (fart #t))
+    (cond [(>= x-left (/ UFO-WIDTH 2))
+           (ufo x-left y fart)]
+          [else current-state])))
+
+(define (ufo-move-right current-state)
+  (let ((x-right (+ (ufo-x current-state) MOVE-LEN))
+        (y (ufo-y current-state))
+        (fart #t))
+    (cond [(<= x-right (- WORLD-WIDTH (/ UFO-WIDTH 2)))
+           (ufo x-right y fart)]
+          [else current-state])))
+
+
+;;; big bang functions
+(define (draw-a-ufo current-state)
+  (place-image (overlay/align/offset
+                "middle" "bottom" UFO 0 35
+                (if (ufo-fart current-state)
+                    UFO-FART
+                    (circle 0 "outline" "white")))
+               (ufo-x current-state)
+               (ufo-y current-state)
+               (empty-scene WORLD-WIDTH WORLD-HEIGHT)))
+
+(define (add-3-to-posy current-state)
+  (ufo (ufo-x current-state)
+           (+ (ufo-y current-state) 3)))
+
+(define (posy-is-300 current-state)
+  (>= (ufo-y current-state) 300))
+
+(define (move-ufo current-state key)
+  (cond [(key=? key "up") (ufo-move-up current-state)]
+        [(key=? key "down") (ufo-move-down current-state)]
+        [(key=? key "left") (ufo-move-left current-state)]
+        [(key=? key "right") (ufo-move-right current-state)]
+        [else current-state]))
+
+(define (ufo-stopped current-state key)
+  (let ((fart #f))
+    (ufo (ufo-x current-state) (ufo-y current-state) fart)))
+
+;;; the big bang
+(big-bang (ufo (/ WORLD-WIDTH 2) (/ WORLD-HEIGHT 2) #f)
+          (to-draw draw-a-ufo)
+          (on-key move-ufo)
+          (on-release ufo-stopped))
+