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A turmite is a Turing machine which has an orientation as well as a current state and a "tape" that consists of an infinite two-dimensional grid of cells. Adapted from:
;; Turmites
;; --------
;; A simple N-state two-color Turing machine which operates on a wrapped
;; grid of black and white cells, and follows custom rules on every tick of
;; a clock.
;; Predef rules derived from
;; Copyright (c) Richard Hull 2012
;; Licensed as per the eclipse public license - v 1.0:
(ns turmites.demo
(:use [enchilada :only [ctx canvas]]
[monet.canvas :only [get-context get-pixel fill-rect fill-style save restore]]
[monet.core :only [animation-frame]]
[jayq.core :only [$ document-ready data text attr hide show bind prevent]]
[jayq.util :only [log]]
[clojure.string :only [split]]))
(def offsets
{ :north [0 -1]
:east [1 0]
:south [0 1]
:west [-1 0] })
(def directions
{ :north { 1 :north 2 :east 4 :south 8 :west }
:east { 1 :east 2 :south 4 :west 8 :north }
:south { 1 :south 2 :west 4 :north 8 :east }
:west { 1 :west 2 :north 4 :east 8 :south }})
(def predef-rules
{ :langtons-ant "120080"
:fibonacci "181181121010"
:binary-counter "120010"
:filled-triangle "081121110111"
:box-spiral "011081120011"
:striped-spiral "021080181020"
:stepped-pyramid "021080181110"
:contoured-island "021011121180"
:woven-placemat "021021110021"
:snowflake-ish "021121181180"
:slow-city-builder "180011080081"
:computer-art "180121020081"
:ballon-bursting "180121021180"
:horizontal-highway "181080110010"
:highway1 "181080121120"
;:highway2 "181081121080"
:filled-spiral "181010110120"
:glaciers "181020080080"
:fizzy-spill "181120080080"
:nested-cabinets "181121110011"
:cross "111081120111"
:saw "111010020180"
:curves-in-blocks "111011121010"
:textured "111020080080"
:diamond "111021180120"
:coiled-rope "111180121010"
:growth1 "120081180011"
:square-spiral "120081180021"
:loopy "120121010011"
:square-ant "121081110010"
;:growth2 "121020081180"
:distracted-spiral "121020010121"
:cauliflower-stalk "121021110111"
:worm-trails "121181121020"
:two-way-highway "121110110011"
:mould-bloom "121120010010"
:highway3 "121120020111"
:highway4 "121121181020"
:square-diagonal "021121082080122180"
;:streak1 "181010022180121110"
:streak2 "181012022111121110"
:maze "181181110012081111"
:cornices "182020180020080081"
:highway5 "120022080020011180"
:highway6 "121080122010180080"
(defn- pair
"Pulls apart a string separated by a = into constituent vector parts,
coverts the key into a keyword"
(let [[k v] (split s #"=")]
[(keyword k) v]))
(defn get-params
"Extracts a set of key-value pairs separated by & into a map"
(let [drop1 (apply str (drop 1 (seq s)))]
(split drop1 #"&")
(map pair)
(into {}))))
(defn parse-rules
"Slices & dices a linear rule (e.g '120121010011') into state based
tuples (e.g: [[(1 2 0) (1 2 1)] [(0 1 0) (0 1 1)]] )"
(seq s)
(map int) ; not quite compatible with clojure!?!
(partition 3)
(partition 2)
(map vec)
(defn get-color
"Fetches the color at the given pixel on the canvas context"
[ctx [x y] scale]
(get-pixel ctx (* x scale) (* y scale)))
(defn set-color! [ctx [x y] scale color]
(-> ctx
(fill-style color)
(fill-rect { :x (* x scale) :y (* y scale) :w scale :h scale})))
(def black?
(fn [color]
[:green :blue]
(map color)
(reduce +)
(defn current-position [turmite]
(get-in turmite [:current :position]))
(defn toggle-previous! [turmite]
(let [prev (turmite :previous)
color (if (= 0 (turmite :color)) "black" "white")]
(if (seq (prev :position))
(set-color! (turmite :ctx) (prev :position) (turmite :cell-size) color))))
(defn draw! [turmite color]
(-> (turmite :ctx)
(current-position turmite)
(turmite :cell-size)
(defn wrap [[x y] [w h]]
[(mod x w) (mod y h)])
(defn color-mapper [color]
(if (black? color) 0 1))
(defn next-triple [turmite]
(let [state (get-in turmite [:current :state])
color (color-mapper (get-color (turmite :ctx) (current-position turmite) (turmite :cell-size)))]
(get-in turmite [:rule :parsed state color])))
(defn relative-direction [current nextdir]
(get-in directions [current nextdir]))
(defn next-state
"The turmite is transitioned based on its current state and the color of
the underlying grid element according to its embedded rule definition."
(let [[color dir state] (next-triple turmite)
new-direction (relative-direction (turmite :direction) dir)
pos (wrap
(map + (current-position turmite) (new-direction offsets))
(turmite :bounds))]
(assoc turmite
:generation (inc (turmite :generation))
:direction new-direction
:color color
:previous (turmite :current)
:current {:position pos :color color :state state})))
(defn animate
"Main animation step-off point, which indefinitely schedules the next
animation frame, updating the termite based on its next state."
(letfn [(loop []
(animation-frame loop)
(let [t @turmite]
(reset! turmite (next-state t))
(toggle-previous! t)
(draw! t "red")))]
(log (pr-str @turmite))
(defn create-turmite
"Creates the turmite map based on the desired position, screen dimensions,
rule, etc."
[ctx pos bounds cell-size rule]
:generation 0
:ctx ctx
:cell-size cell-size
:bounds bounds
:direction (get [:north :east :south :west] (rand-int 4))
:current { :position pos :color (color-mapper (get-color ctx pos cell-size)) :state 0}
:previous nil
:rule rule
(defn coords
"Gets the co-ordinates from the event, and scale to the cell size"
[event scale]
[ (quot (.-offsetX event) scale)
(quot (.-offsetY event) scale) ])
(defn get-rule
"Extracts and parses the rule from the URL query string. If no rule=
exists then one is selected at random. If the value is a predefined
rule then that is used, otherwise an attempt is made to parse the
value into a rule definition."
(let [input ((get-params query-string) :rule)
label (if (nil? input)
(nth (keys predef-rules) (rand-int (count predef-rules)))
rule (get predef-rules (keyword label) input)
{ :name (name label) :data rule :parsed (parse-rules rule) }))
(defn available-area
"Calculates the maximum available screen size"
(let [div (first ($ :div#wrapper))]
[ (.-offsetWidth div) (.-offsetHeight div) ]))
(fn []
(show canvas)
(-> ctx (fill-style :black) (fill-rect { :x 0 :y 0 :w 800 :h 600}))
(let [cell-size 3
width 798
height 600
rule (get-rule (.-search (.-location js/window)))]
(bind canvas :click
(fn [event]
(prevent event)
(animate (create-turmite ctx (coords event cell-size) [width height] cell-size rule))))
(animate (create-turmite ctx [100 60] [width height] cell-size rule)))))
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