net: Add loco.rkt.

* net/ricketyspace/ror/five/loco.rkt: New file.
* net/ricketyspace/ror/five/resources/caroille.png: New file.
* net/ricketyspace/ror/five/resources/caroille.svg: New file.

3 files changed, 184 insertions, 0 deletions

diff --git a/net/ricketyspace/ror/five/loco.rkt b/net/ricketyspace/ror/five/loco.rkt
new file mode 100644
index 0000000..977c976
--- /dev/null
+++ b/net/ricketyspace/ror/five/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/net/ricketyspace/ror/five/resources/caroille.png b/net/ricketyspace/ror/five/resources/caroille.png
new file mode 100644
index 0000000..052cc58
--- /dev/null
+++ b/net/ricketyspace/ror/five/resources/caroille.png
diff --git a/net/ricketyspace/ror/five/resources/caroille.svg b/net/ricketyspace/ror/five/resources/caroille.svg
new file mode 100644
index 0000000..eb4db63
--- /dev/null
+++ b/net/ricketyspace/ror/five/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/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="80"
+   height="80"
+   viewBox="0 0 21.166666 21.166667"
+   version="1.1"
+   id="svg8"
+   inkscape:version="0.92.3 (2405546, 2018-03-11)"
+   sodipodi:docname="caroille.svg">
+  <title
+     id="title3715">caroille</title>
+  <defs
+     id="defs2">
+    <inkscape:perspective
+       sodipodi:type="inkscape:persp3d"
+       inkscape:vp_x="1.8428503 : 18.575596 : 1"
+       inkscape:vp_y="0 : 999.99999 : 0"
+       inkscape:vp_z="28.301183 : 18.575596 : 1"
+       inkscape:persp3d-origin="15.072016 : 14.165874 : 1"
+       id="perspective3723" />
+  </defs>
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.0"
+     inkscape:pageshadow="2"
+     inkscape:zoom="3.959798"
+     inkscape:cx="72.620745"
+     inkscape:cy="61.452165"
+     inkscape:document-units="mm"
+     inkscape:current-layer="layer1"
+     showgrid="false"
+     units="px"
+     showguides="false"
+     inkscape:window-width="1280"
+     inkscape:window-height="800"
+     inkscape:window-x="0"
+     inkscape:window-y="0"
+     inkscape:window-maximized="0" />
+  <metadata
+     id="metadata5">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title>caroille</dc:title>
+        <cc:license
+           rdf:resource="http://creativecommons.org/publicdomain/zero/1.0/" />
+        <dc:date>2018-04-02</dc:date>
+        <dc:creator>
+          <cc:Agent>
+            <dc:title>rsiddharth &lt;s@ricketyspace.net&gt;</dc:title>
+          </cc:Agent>
+        </dc:creator>
+        <dc:subject>
+          <rdf:Bag>
+            <rdf:li>car</rdf:li>
+          </rdf:Bag>
+        </dc:subject>
+      </cc:Work>
+      <cc:License
+         rdf:about="http://creativecommons.org/publicdomain/zero/1.0/">
+        <cc:permits
+           rdf:resource="http://creativecommons.org/ns#Reproduction" />
+        <cc:permits
+           rdf:resource="http://creativecommons.org/ns#Distribution" />
+        <cc:permits
+           rdf:resource="http://creativecommons.org/ns#DerivativeWorks" />
+      </cc:License>
+    </rdf:RDF>
+  </metadata>
+  <g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1"
+     transform="translate(0,-275.83332)">
+    <g
+       id="g3759"
+       transform="matrix(1.6602564,0,0,1.6602564,-10.597836,-177.21015)"
+       inkscape:export-xdpi="96"
+       inkscape:export-ydpi="96">
+      <rect
+         ry="0.8018086"
+         style="stroke-width:0.26458332"
+         y="277.95703"
+         x="7.550364"
+         height="3.4745038"
+         width="10.423512"
+         id="rect3717" />
+      <circle
+         style="stroke-width:0.26458332"
+         r="1.1692964"
+         cy="281.3313"
+         cx="9.254199"
+         id="path3719" />
+      <circle
+         id="circle3721"
+         cx="15.969346"
+         cy="281.49835"
+         r="1.1692964"
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+         ry="1.1693041"
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+         width="5.9133382"
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+    </g>
+  </g>
+</svg>