[sugar] Ideas about SimCity gui, turtle graphics, and cellular automata

Don Hopkins dhopkins at DonHopkins.com
Wed Mar 14 02:50:15 EDT 2007

SimCity in Python will be totally programmable in Python, so what should 
we program it to do?  And how can we refactor it into general purpose, 
reusable components?

Here is an outline (at the end of this message) of some ideas I've had 
about simplifying the SimCity user interface and making it more fun and 
educational. It should be easy and fun for little kids to use, work well 
in book mode with the game controller, support the mouse but not require 
it, and enable collaboration over the network with other players.

Instead of (or in addition to) using the mouse to paint with a palette 
of editing tools like Photoshop, the interface could be based on agents 
like logo turtles that represent the user on the map, which carry around 
SimCity editing tools that they can draw with. When you throw in a 
visual programming language, it leads the way to a Robot-Odyssey-esque 
version of SimCity!

This is one reason I want to have a nice plug-in visual programming 

Just for fun, and for the enjoyment of cellular automata freaks and von 
Neumann fans, here is a nerd toy I wrote in OpenLaszlo (a von Neumann 29 
State CA editor and simulator), with a cellular automata grid editing 
tool that you can move around over the grid and edit the map like an 
agent or logo turtle, using the keyboard or mouse. It's a half-baked 
experimental user interface, so I'm not claiming that it isn't bizarre 
or doesn't suck, but it does demonstrate some ideas that might be 
applied to the SimCity user interface.

John von Neumann's 29 state Cellular Automata Implemented in OpenLaszlo

Full window demo in Flash player:

Source code:

The arrow keys move the tool, space clears the cell under the tool, the 
letter diamonds "wasz"/"rdfc" make an unexcited ordinary/special 
directional arrow cell in the corresponding direction, and "WASD"/"RDFC" 
make excited versions of those arrow cells, other letters and numbers 
are for miscellaneous states, and so on. The "." key advances the 
current cell to the next logical state, so you can toggle the excited 
state of any arrow cell in a standard way without changing its 
direction, or cycle confluent cells through their four states. Clicking 
the mouse on the tool pops of a pie menu with submenus of all possible 
states organized by category (some of which arrange naturally into pie 
menus, because they are directionally oriented). Clicking the mouse 
anywhere else moves the tool to that cell. The goal is to be able to 
quickly key in a cellular automata configuration, as well as randomly 
accessing and editing it (even while it's running).

[I'm not going to attempt to explain how the CA itself works (just press 
"Run" and enjoy the blinking lights), but it's based on one of my 
favorite classics: John von Neumann's 29 state CA rule, which he 
specifically designed (on paper!) to program self-reproducing machines. 
The source code has some good references and obtuse comments! Sadly, the 
Flash player is way too slow to run enough cells to actually house a 
complete self-reproducing machine (and its offspring, and their 
offspring...) in their full glory and splendor. Fortunately I do have an 
efficient C++ implementation of that rule (and others), as a Python 
extension! Once we have a good tile display/editing engine in Python, it 
will be fun to hook that code up to drive it, and efficiently run huge 
self-reproducing cellular automata!]

For hard core cellular automata freaks: Hit "Next" a few times till you 
get to "Autoinitializing Exclusive Or", then hit "Load" then "Run", to 
see a cool self modifying cellular automata bootstrap! A special signal 
of 5 excited states in a row goes through first, which initializes the 
circuit, ignites all the pilot lights and synchronizes all its internal 
clocks at just the right time and phase, and then cuts off the ignition 
circuit (blows the explosive bolts so to speak, with construction 
commands) so the circuit is only initialized once, and subsequent 
signals flow through the normal part of the circuit. In this case, the 
circuit performs an exclusive-or (which is easier said than done in this 
rule, requiring synchronized clocks), two of which are needed to cross 
two signals without interfering. The point of all this, is that machines 
in this CA rule can only construct other machines in the powered-off 
state (or they might get electrocuted ;-), so there has to be a way to 
turn a machine on and start all its clocks ticking by 
"autoinitialization" -- self modifying CA code! The self-reproduction 
process has two phases: first build a copy of yourself in the 
powered-down ready-to-initialize state, by scanning back and forth with 
the builder arm like an ink jet printer, programmed from a huge spiral 
of memory (the machine's dna). Then once you're done, dock your 
construction arm into the new machine's naval at the base of it's memory 
loop (like an umbillical cord for data), then switch into playback mode 
and loop all your memory back through, injecting a copy of it into the 
duplicate's memory loop. Then send a start signal to initialize the copy 
and start it reproducing itself. This stuff was described (and 
illustrated ;-) in a paper by William R. Buckley and Amar Mukherjee. The 
examples in this demo show different ways to effect a signal crossings 
(with different advantages and disadvantages). Some (like the real time 
crossing) are not "constructible", and some have interference problems 
(like the coded channel crossing), and some are enormous (like two 
autoinitializing exclusive or's). Of course people have come up with 
much more efficient rules since then (and that is a fun game too), but 
John von Neumann's 29 state rule is classic coke, the real thing.


Redesigning the SimCity user interface for the OLPC
Don Hopkins

    Visual Programming

      Simplify the SimCity interface and make it easier for kids to
      use it with the game controller, in a way that will support
      multi player interaction.

      Collapse the separate concepts of game editing tool (bulldozer,
      road, residential zone, etc) and agent (sprites like the
      monster, tornado, helicopter, train, etc).

      Agents with specialized tool represent different roles that kids
      can play. A bunch of kids can join together and play different
      roles at the same time in the same city. Instead of having a
      bunch of editing tools to switch between, you have a bunch of
      different agents you can drive around the map, like using a
      monster to crush things instead of a bulldozer, or riding around
      in a helicopter to scroll around and observe the map. Make a
      meta-game like pokemon trading cards or magic the gathering,
      about acquiring and deploying and using agents on the map. Give
      agents different budgets and constraints.

      Use an agent to represent a user in the world, and control an
      editing tool. You see other users in the map driving around
      their editing tool agents.

      Each editing tool can be associated with a particular agent,
      with a keyboard/game controller based user interface for moving
      around, as well as a mouse based interface for picking it up and
      dragging it around.

      The road tool becomes a road building vehicle, that you can
      easily move up/down/left/right/diagonally with the game
      controller directional input. Requires much less coordination to
      draw straight roads than with a mouse. 

      The bulldozer tool becomes an actual bulldozer that you can
      drive around the map, crushing things in your wake.

      This makes the game easily usable by little kids in book mode. 

      Also support small children using SimCity like a drawing tool or
      etch-a-sketch, simply doodling with the editing tools for the
      visceral pleasure of it, and setting fires and other disasters
      to watch it burn and mutate.

      Logo Turtles (as a generalization of the monster, tornado,
      helicopter, etc)

        Implement programmable logo turtles as agents that can move
        around on the map, sense it, and edit it. 

	Like Robot Odyssey agents, so you can go "inside" an agent,
	and travel around with it, operate its controls, read its
	sensors, and automate its behavior by wiring up visual programs
	with logic and math and nested "ic chip" components.

	Plug in graphics to represent the agent: use classic logo
	turtle and SimCity sprites, but also allow kids to plug in
	their own.
	  SimCity sprites have 8 rotations. 
	  SVG or Cairo drawings can be rotated continuously.

        Re-implement the classic SimCity agents like the monster,
        tornado, helicopter, train, etc in terms of logo turtles, that
        kids can drive around, learn to use, open up and modify (by
        turning internal tuning knobs, or even rewiring).

	Let kids reprogram the agents to do all kinds of other stuff.

	Mobile robots, that you can double click to open up into
	Robot-Odyssey-esque visual program editors.

	Agents have local cellular-automata-like sensors to read
	information about the current and surrounding tiles.

	KidSim / Cocoa / StageCraft Creator let kids define visual
	cellular automata rules by example, based on tile patterns and
	rules. Show it a pattern that you want to match by selecting
	an instance of that pattern in the world, then abstract it
	with wildcards if necessary, then demonstrate the result you
	want it to change the cell to in the next generation.

	Sense high level information about zones and overlays, so the
	agents can base their behavior on any aspect of the world

	  Support an extensible model by allowing users to add more

	    Add layers with arbitrary names and data types at
	    different resolutions:

	      byte, int, float, n-dimensional vector, color, boolean
	      mask, musical note, dict, parametric field (i.e. perlin
	      noise or other mathematical function) at each cell, etc.

	Edit the world. 

	  All SimCity editing tools (including colored pens that draw
	  on overlays) should be available to the agent.

	  Enable users to plug in their own editing tools, that they
	  can use themselves with the mouse, keyboard or game
	  controller, or program agents to use to edit the map under
	  program control.

      Robot Odyssey

        Build your own universal programmable editing tool.
	Roll your own von Neuman Universal Constructor. 
	Smart robots you program to perform special purpose editing tasks. 

	The "Painter" picture editing program had a way of recording
	and playing back high level editing commands, relative to the
	current cursor position.

	Remixing. Journaling. Programming by demonstration or example.
	You could use a tape recorder to record a bunch of SimCity
	editing commands that you act out (or you can just select them
	from the journal), then you can play those tapes back with
	relative coordinates, so they apply relative to where the
	agent currently is on the map. You can copy and paste and cut
	and splice any editing commands into tapes that you can use to
	program the robot to play back in arbitrary sequences. 

	Program an urban sprawl development-bot to lay out entire
	residential subdivisions, complete with zones, roads, parks and
	wires. Then program a luddite roomba-bot that sucks them all
	up and plants trees in their place.

	This becomes really fun when we let players plug in their own
	programmed zones for the robot to lay out, and layers of data
	to control the robot's behavior, out of which they can program
	their own cellular automata rules and games (like KidSim /
	Cocoa / StageCraft Creator).

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