//RULESET:

// 1) Each cell state is the average update of its neighbor and previous state

// 2) Two grids: Current holds current wave height; Previous holds wave from past time

// 3) Use Wave equation and add a damping factor to reduce wave energy

​

//Wave Equation: current[i][j] = 2 * previous[i][j] + damping(avg. neighbor - previous[i][j])

//The equation calculates the cell 'height' and determines its color based on this!

​

//START

let cols, rows;

let resolution = 10; //Cell size

let current, previous, islands;

let damping = 1; // Wave damping speed 

function setup() {

  createCanvas(600, 600);

  cols = width / resolution;

  rows = height / resolution;

​

  // Initialize grids

  current = make2DArray(cols, rows);

  previous = make2DArray(cols, rows);

  islands = make2DArray(cols, rows);

​

  // Generate random islands

  generateIslands();

}

​

function draw() {

  background(0);

  frameRate(12);

​

  // Draw CURRENT wave state & Islands 

  // Iterate over the cells

  for (let i = 0; i < cols; i++) {

    for (let j = 0; j < rows; j++) {

      let x = i * resolution;

      let y = j * resolution;

      //Check if cell is islands 

      if (islands[i][j] == 1) {

        fill(0); 

      } else {

        let value = current[i][j];

        fill(127 + value * 127); //This colors the wave based on height value 

      }

      rect(x, y, resolution, resolution);

    }

  }

​

  // Compute the next wave state

  let next = make2DArray(cols, rows);

  for (let i = 1; i < cols - 1; i++) {

    for (let j = 1; j < rows - 1; j++) {

      if (islands[i][j] == 1) {

        //DO NOTHING IF IT IS ISLANDS!

        next[i][j] = 0;

      } else {

        // Add the wave equation!

        next[i][j] =

          (2 * current[i][j] - previous[i][j]) +

          damping *

            ((current[i - 1][j] +

              current[i + 1][j] +

              current[i][j - 1] +

              current[i][j + 1]) /

              4 -

              current[i][j]);

      }

    }

  }

​

  // Update grids

  previous = current;

  current = next;

​

  // MOUSE PRESS INTERACTION

  if (mouseIsPressed) {

    let x = floor(mouseX / resolution);

    let y = floor(mouseY / resolution);

    if (x > 0 && x < cols && y > 0 && y < rows && islands[x][y] == 0) {

      current[x][y] = 1;

    }

  }

}

​

//FUNCTION TO MAKE 2D ARRAYS 

function make2DArray(cols, rows) {

  let arr = new Array(cols);

  for (let i = 0; i < cols; i++) {

    arr[i] = new Array(rows).fill(0);

  }

  return arr;

}

​

//FUNCTION TO GENERATE ISLANDS 

function generateIslands() {

  // Randomly generate islands of varying sizes

  for (let n = 0; n < 17; n++) { // Generate n number of islands 

    let startX = floor(random(cols));

    let startY = floor(random(rows));

    let size = floor(random(1, 10)); // Island size up to 5x5

​

    for (let i = startX; i < startX + size && i < cols; i++) {

      for (let j = startY; j < startY + size && j < rows; j++) {

        islands[i][j] = 1; //Turn cell into 1 if it is an Island 

      }

    }

  }

}

​