# Inputs must be given

#demand width is _.

​

# Create a grid of regions, connected Manhattan-style

#builtin INT_MINUS minus

dim width.

dim (minus N 1) :- dim N, N > 1.

region (coord X Y) :- dim X, dim Y.

next_to (coord X Y) (coord (minus X 1) Y) :- dim X, dim Y, X > 1.

next_to (coord X Y) (coord X (minus Y 1)) :- dim X, dim Y, Y > 1.

next_to R1 R2 :- next_to R2 R1.

​

# Each region can be mountains, forest, or ocean

terrain R is { mountain, forest, ocean } :-

   region R.

​

# Mountains can't be next to the ocean

terrain R1 is { forest, ocean } :-

    next_to R1 R2,

    terrain R2 is ocean.

​

# Spanning tree rooted at the start

parent (coord 1 1) is (coord 1 1).

parent R2 is? R1 :-

    can_reach R1,

    terrain R1 is forest,

    next_to R1 R2.

can_reach R :- parent R is _.

​

# Connected components for oceans to ensure only one ocean

ocean_rep R is? R :- terrain R is ocean.

ocean_rep R2 is R :- ocean_rep R1 is R, next_to R1 R2, terrain R2 is ocean.

#forbid ocean_rep R1 is R, ocean_rep R2 is R', R != R'.

​

# You must be able to reach the lower-right, and ocean, and mountans

#demand can_reach (coord width width).

#demand can_reach R, terrain R is forest.

#demand can_reach R, terrain R is ocean.`);

​

const WIDTH = 6;

const CELL_SIZE = 50;

const REGIONS = {

  forest: [71,191,107],

  ocean: [77,176,209],

  mountain: [152,157,158],

}

​

MAP_GEN.assert({name: 'width', value: WIDTH });

​

function setup() {

  createCanvas(WIDTH * CELL_SIZE, WIDTH * CELL_SIZE);

}

​

function draw() {

  const solution = MAP_GEN.sample();

  text("🏠")

  noStroke();

  for (let x = 1; x <= WIDTH; x++) {

    for (let y = 1; y <= WIDTH; y++) {

      const { name: terrain } = solution.get("terrain", ({name: 'coord', args:[x, y]}));

      fill(...REGIONS[terrain]);

      square((x-1)*CELL_SIZE, (y-1)*CELL_SIZE, CELL_SIZE);

    }

  }

  stroke(0);

  let next;

  for (let coord = [WIDTH, WIDTH]; coord[0] > 1 || coord[1] > 1; coord = next) {

    next = solution.get("parent", {name: 'coord', args: coord}).args;

    line((coord[0]-0.5)*CELL_SIZE, (coord[1]-0.5)*CELL_SIZE, (next[0]-0.5)*CELL_SIZE, (next[1]-0.5)*CELL_SIZE);

  }

}

​