// Author: Christian Manderla

// adaptation of Marching Cubes algorithm to an underlying grid of hexagons

// possible use: map generation for role playing games

// each corner of each hexagon is connected to a perlin noise value on a basis

// of their x/y-position

// those values are rounded to 0 or 1.

// corners associated to 1 are enclosed in dark areas.

// for animation a third offset in the noise space is incremented

// known weaknesses:

// * no interpolation

// * hex-grid must have the same number of cells in every line

// * ineffective due to redundancy. Most cornervalues are calculated 3 times

//   due to beeing seen as e.g. south corner of 1 tile, northeast corner of 1 tile

//   and northwest corner of a third tile

// Benefits over usual marching swuares

// * underlying hexgrid is wanted in some circumstances

// * slightly softer/more organic looking than marching squares 

​

// Variables for customizing the result

​

// higher smooting leads to less but bigger structures

let smoothing = 60;

// speed of change

let speed = 0.01;

// "diameter" of the hexagons; less cellsize leads to more cells aka higher resolution

const cellsize = 20;

​

​

const nodes = [];

​

​

let cols;

let rows;

​

const xstep = cellsize;

const ystep = cellsize * (Math.sqrt(3) / 2);

​

let offset = 0;

​

​

function setup() {

  createCanvas(800, 450);

​

  cols = floor((width - cellsize/2) / cellsize);

  rows = floor(height / ystep);

​

  buildGrid(rows, cols);

}

​

function draw() {

  background(100);

​

  for (let n of nodes) {

    n.show();

    n.marchingHexes();

    n.updateCornerValues();

  }

  offset += speed;

}

​

​

function buildGrid(rows, cols) {

  let indent = false;

  let x = xstep / 2;

  let y = (ystep / 5) * 4;

​

  for (let j = 0; j < rows; j++) {

    for (let i = 0; i < cols; i++) {

      nodes.push(new HexField(x, y, xstep / sqrt(3), nodes.length));

      x += xstep;

    }

    y += ystep;

    if (indent) {

      x = xstep / 2;

    } else {

      x = xstep;

    }

    indent = !indent;

  }

}