Wireworld

Everyone knows the classic example of cellular automata, Conway’s Game of Life. Instead of rehashing an implementation of that, I wanted to build something just a little bit different while learning the Nim language.

I decided to implement another type of cellular automata, Wireworld, first conceived by Brian Silverman in 1987. The code for this could easily be modified to produce Conway’s Game of Life by adjusting the State type and the process(world: ref World) procedure.

Build

C target

Build the project from source by typing nim c display.nim into your terminal. You must have Nim installed already, as well as the SDL 2 module. You can install the SDL 2 module by running nimble install sdl2.

Run the project by calling ./display in the appropriate directory.

You may need do create a libSDL2.so symlink if you get the following error: could not load: libSDL2.so

/usr/lib/x86_64-linux-gnu$ ln -s libSDL2-2.0.so.0 libSDL2.so

JavaScript target

Nim 0.17.0 is required, it won’t build with Nim 0.15.2 (eg. which is the distributed version on the latest Ubuntu, get the 0.17 .deb)

Install html5_canvas: nimble install html5_canvas

Build the JS: nim js canvas.nim

Open the webpage: firefox wireworld.html

Description

This automata simulates a simple abstraction of electricity.

It has four states:

• Ground
• Wire
• Electron head
• Electron tail

The propagation rules are:

• Ground -> Ground
• Electron head -> Electron tail
• Electron tail -> Wire
• If Wire has exactly 1 or 2 neighbors == Electron Head:
  • Wire -> Electron Head
• Otherwise:
  • Wire -> Wire

Implementation

This implementation is built in Nim using the SDL 2 library.

Thanks to GitHub user tylorr for taking it upon himself to make a web frontend for this project as well.

Features and Instructions

Clicking on the map changes the tile under the cursor to the current drawmode’s type.

The info bar at the bottom of the window indicates the currently selected draw mode on the left half, and the paused/play state of the simulation on the right half.

There are four drawing modes, one for each state:

• A: Ground mode
• S: Wire mode
• D: Electron head mode
• F: Electron tail mode

In addition there are a few other keybindings:

• Up: Increases the speed of the simulation by 1 tick per second (Min: 1, Max: 60)
• Down: Decreases the speed of the simulation by 1 tick per second
• Q: Quit Wireworld
• R: Clear the current world
• P: Pause or Play the simulation (can draw while paused or playing)

Future Additions

• [ ] Undo
• [ ] Save and load worlds from file