// 

// Jared Donovan 2022

//

// Implementation of the 'rule 30' cellular automata

// 

​

let siz = 10;

let cells = [];

let rows, cols;

let idx = 0;

let rule = [

  [false, true, true, true],

  [true, false, false, false]

];

​

function setup() {

  createCanvas(400, 400);

  //stroke(50);

  noStroke();

  rows = height / siz;

  cols = width / siz;

  for (let row = 0; row < rows; row++){

    cells.push([])

    for (let col = 0; col < cols; col++){

      cells[row][col] = false;      

    }

  }

​

  // Set the middle one true to begin with

  cells[0][floor(cols / 2)] = true;

}

​

function draw() {

  background(220);  

​

  if (idx < rows - 1){

    idx += 1;

  } else {

    // Copy each row down one

    cells.shift();

    cells.push(new Array(cols).fill(false));    

  }

  drawCells();

​

  //stroke(255, 0, 0);

  //line(0, idx * siz, width, idx * siz);

​

  // Calculate next row (shown on next draw loop)

  for (let col = 0; col < cols; col++){

    let row = idx;

    let prevRow = idx - 1;

​

    // Wrapping

    // let a = cells[prevRow][((col - 1) + cols) % cols] ? 1:0;

    // let b = cells[prevRow][col    ] ? 2 : 0;

    // let c = cells[prevRow][(col + 1) % cols] ? 1 : 0;

    let a = cells[prevRow][col - 1] ? 1:0;

    let b = cells[prevRow][col    ] ? 2 : 0;

    let c = cells[prevRow][(col + 1)] ? 1 : 0;

​

    if (col == 0){

      a = 0;

      if (b){

        a = random(100) > 20 ? 1 : 0;

      }

    }

​

    if (col == cols - 1){

      c = 0;

      if (b){

        c = random(100) > 20 ? 1 : 0;

      }      

    }

    cells[row][col] = rule[c][a + b];

  }

  // 

  //noLoop();

}

​

function drawCells(){

  for (let row = 0; row < rows; row++){

    for (let col = 0; col < cols; col++){

      if (cells[row][col]){

        fill(0);

      } else {

        fill(255);

      }

      //stroke(50);

      square(col * siz, row * siz, siz);      

    }

  }  

}

​

function keyPressed(){

  if (key == ' ' ){

    loop();

  }

}