; based off of the Vants model that comes with NetLogo patches-own [value] globals [movie-steps frame-count] to setup clear-all ask patches [ set pcolor 0 ] crt num-vants [ face one-of neighbors4 set color red set size 0 ] ;; I don't want to see turtles. end ;; We can't use "ask turtles", because then the vants would ;; execute in a different random order each time. So instead ;; we use SORT to get the turtles in order by who number. to go-forward foreach sort turtles [ ask ? [ fd step-len turn ] ] tick end to turn set value ((value + value-inc) mod 16777216) ;set pcolor rgb ((value / 65536) mod 256) ((value / 16) mod 256) (value mod 256) set pcolor rgb ((value / 32) mod 256) ((value / 32) mod 256) ((value / 256) mod 256) ifelse value mod decision-mod = 0 [ rt turn-angle ] [ lt turn-angle ] ;if value > 255 and value mod 256 = 0 [ ; hatch 1 [ lt turn-angle fd step-len ] ;] ;if value > 255 and value mod 257 = 0 [ ; die ;] end to-report turtle-count report count turtles end to-report percent-rendered report (frame-count * 100) / movie-steps end to make-movie movie-start "out1.mov" movie-set-frame-rate 30 movie-grab-view ;; show the initial state let frame-total 2700 let tick-skip 5000 set frame-count 0 set movie-steps frame-total repeat frame-total [ repeat tick-skip [ go-forward ] movie-grab-view set frame-count frame-count + 1 ] movie-close end ; Copyright 2005 Uri Wilensky. All rights reserved. ; The full copyright notice is in the Information tab. @#$#@#$#@ GRAPHICS-WINDOW 220 10 870 521 -1 -1 1.0 1 10 1 1 1 0 1 1 1 0 639 0 479 1 1 1 ticks BUTTON 47 73 170 106 NIL setup NIL 1 T OBSERVER NIL NIL NIL NIL BUTTON 67 166 151 199 forward go-forward T 1 T OBSERVER NIL NIL NIL NIL SLIDER 18 38 207 71 num-vants num-vants 1 16 10 1 1 NIL HORIZONTAL BUTTON 42 570 150 603 NIL make-movie NIL 1 T OBSERVER NIL NIL NIL NIL SLIDER 19 310 191 343 step-len step-len 0.1 5 0.5 0.1 1 NIL HORIZONTAL SLIDER 19 359 191 392 turn-angle turn-angle 1 90 90 1 1 NIL HORIZONTAL SLIDER 19 404 191 437 value-inc value-inc 1 256 11 1 1 NIL HORIZONTAL SLIDER 19 452 191 485 decision-mod decision-mod 2 150 14 1 1 NIL HORIZONTAL MONITOR 258 568 386 613 NIL turtle-count 17 1 11 MONITOR 435 565 559 610 NIL percent-rendered 3 1 11 @#$#@#$#@ WHAT IS IT? ----------- This is a basic virtual ant ("vant") model. It shows how extremely simple deterministic rule can result in very complex-seeming behavior. It also demonstrates the concept of time reversibility and shows that time reversibility is not incompatible with complex behavior. HOW IT WORKS ------------ The world is a grid of patches. Each patch can be either black or white. Initially, they are all white. The rules the "vants" (virtual ants) follow are very simple. Each vant faces north, south, east, or west. At each time step, a vant moves to the next patch. Then it looks at the new patch: - If the new patch is white, the vant colors the patch black and turns right 90 degrees. - If the new patch is black, the vant colors the patch white and turns left 90 degrees. That's it! The world wraps, so when a vant moves off one side of the view it reappears at the other side. HOW TO USE IT ------------- The SETUP button colors all the patches white and creates a number of vants determined by the the NUM-VANTS slider. Pressing the FORWARD button makes the vants start to move according to the normal rules. You can stop the FORWARD button and then press the REVERSE button instead to make the vants move backwards instead of forwards, while still following the same turning rule. The model runs fairly slowly by default, so you can see every step the vants take. You may want to use the speed slider to speed the model up so you can see what happens when a lot of time passes. THINGS TO NOTICE ---------------- To make it easier to see, the vant is shown as larger than a patch. The resulting patterns sometimes have obvious structure, but sometimes appear random, even though the rules are deterministic. Call the diagonal paths that form "highways". Are there different kinds of highways? THINGS TO TRY ------------- Compare the results with one vant to those with multiple vants. Are there any behaviors you get with multiple vants that don't occur with just one? When there are multiple vants, they are initially given random headings. That means that you may get different looking behavior even with the same number of vants, depending on the directions they start out facing. If you press the REVERSE button, the vants turn then move backwards, instead of moving forwards then turning. The turn rule is the same. What effect does this have? Press SETUP, run the model forwards a little, then stop the GO button and press REVERSE instead. EXTENDING THE MODEL ------------------- Without changing the rules, you could change the visualization by making different vants different colors and color-coding the patches to show which vant touched a patch last. This should make some additional structure apparent to the eye. NETLOGO FEATURES ---------------- You can use the SORT primitive to created a list of turtles sorted by who number. That is necessary in this model because we need the turtles to execute in the same order at every tick, rather than a different random order every tick as would happen if we just said "ask turtles". RELATED MODELS -------------- Turing Machine 2D -- similar to Vants, but much more general. This model can be easily configured to use Vants rules, or to use other rules. CREDITS AND REFERENCES ---------------------- The rules for Vants were originally invented by the artificial life researcher Chris Langton. HOW TO CITE ----------- If you mention this model in an academic publication, we ask that you include these citations for the model itself and for the NetLogo software: - Wilensky, U. (2005). NetLogo Vants model. http://ccl.northwestern.edu/netlogo/models/Vants. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL. - Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL. In other publications, please use: - Copyright 2005 Uri Wilensky. All rights reserved. See http://ccl.northwestern.edu/netlogo/models/Vants for terms of use. COPYRIGHT NOTICE ---------------- Copyright 2005 Uri Wilensky. All rights reserved. Permission to use, modify or redistribute this model is hereby granted, provided that both of the following requirements are followed: a) this copyright notice is included. b) this model will not be redistributed for profit without permission from Uri Wilensky. Contact Uri Wilensky for appropriate licenses for redistribution for profit. @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 Circle -7500403 true true 96 182 108 Circle -7500403 true true 110 127 80 Circle -7500403 true true 110 75 80 Line -7500403 true 150 100 80 30 Line -7500403 true 150 100 220 30 butterfly true 0 Polygon -7500403 true true 150 165 209 199 225 225 225 255 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