Cellular automata guide
Every control
Every control in the panel, top to bottom. The rule, tool and pattern buttons are made when the page loads, so each group has one line here that names them all.
Load and save
They stay at the top while the panel scrolls. Reset puts the controls back: everything goes back to how the page opened, including a new random grid.
- Random fillButton
- Fills about one cell in five at random and sets the generation back to 0. See seed.
- Save PNGButton
- Saves the grid as you see it as a PNG named with the generation, such as cellular-automata-gen120.png.
- Copy imageButton
- Copies the same picture to the clipboard.
- Copy RLEButton
- Copies the live cells as RLE text, the plain format other Life programs read.
Rules
Picking Custom shows the Custom rule box under the buttons. Type a rule as B, the birth counts, a slash, S, and the survive counts, such as B3/S23 or B3678/S34678. Counts run from 0 to 8, and the slash may be left out. The rule changes as you type; text that does not fit the pattern is ignored and the last good rule stays. See rule string.
- RulePick one
- The rule the grid follows. Game of Life is B3/S23. Brian's Brain has three states: an empty cell fires when exactly 2 neighbours fire, a firing cell starts dying (dark green), and a dying cell goes empty. WireWorld has wire, electron heads and tails: a head becomes a tail, a tail becomes wire, and wire becomes a head when 1 or 2 neighbours are heads. Day & Night is B3678/S34678. Seeds is B2/S, so no cell lives twice in a row. Langton's ant clears the grid and puts a yellow ant in the middle: on an empty cell it fills it and turns right, on a filled cell it clears it and turns left, then steps forward. Rule 110 clears the grid and grows a one-line pattern from a single cell at the right edge; each new line appears at the bottom and the rest moves up. Custom runs the B/S rule you type.
- Custom ruleText
- Shows only while Custom is picked. The B/S rule the grid follows, such as
B3/S23; it takes effect as you type. Reset empties it.
Playback
- PlayButton
- Starts the run. While it runs the button reads Pause and stops it.
- StepButton
- Moves the grid on by one generation.
- Clear gridButton
- Empties the grid and sets the generation back to 0. In Rule 110 the single starting cell comes back.
- Generations / secSlider · 1 to 60 · starts at 10
- How many generations run each second, while playing.
Drawing
- Drawing toolPick one
- What dragging on the grid does. Paint fills cells and Erase empties them. Line draws a straight line from where you press to where you let go, and Rectangle draws the outline of a box between those two corners. In WireWorld, Paint, Line and Rectangle draw wire.
Patterns
- PatternPick one
- Known shapes to place. Pick one, then tap the grid: the shape's top-left corner lands on the cell you tap. Glider and LWSS are spaceships that travel. Gosper gun is the Gosper glider gun, which fires a new glider every 30 generations. Pulsar and Pentadecathlon are oscillators. R-pentomino and Acorn are methuselahs: a few cells that take hundreds of generations to settle. In Game of Life terms these are live cells; in WireWorld they are electron heads.
Grid
- Cells per sideSlider · 50 to 500 · starts at 200
- How many cells the square grid has along each side. It takes effect when you press Apply size. Phones stop at 250. See grid size.
- Apply sizeButton
- Rebuilds the grid at the new size. The grid starts empty.
- Grid linesOn or off · starts off
- Draws thin lines between cells. They show only when each cell is at least 4 pixels wide on screen, so zoom in if you do not see them.
- Wrap at the edgesOn or off · starts on
- When on, the grid wraps: the left edge touches the right and the top touches the bottom, so a glider that leaves one side comes back on the other. When off, cells past the edge count as empty. See wrap-around.
Colors
- SchemeChoice
- The colours of live and empty cells: Mint, Neon, Fire, Matrix, Ice, or Custom. Brian's Brain dying cells and WireWorld's wire, heads and tails keep their own colours.
- AliveColour · starts #10B981
- With the Custom scheme, the colour of live cells.
- DeadColour · starts #08080A
- With the Custom scheme, the colour of empty cells.
Stats
Shows the number of live cells, the share of the grid they fill, and a line of the live cell count over the last 200 generations. The line is drawn while the section is open.
Reset
- ResetButton
- Puts every setting back to how the page opened and fills a new random grid.