flying-squid/src/lib/worldGenerations/diamond_square.js

var Chunk = require('prismarine-chunk')(require("../version"));
var Vec3 = require('vec3');

function DiamondSquare(size, roughness, seed) {
  // public fields
  this.size = size;
  this.roughness = roughness;
  this.seed = seed;
  var opCount = 0;

  // private field
  var data = new Array();

  // public methods
  this.value = function(x, y, v) {
    x = parseInt(x);
    y = parseInt(y);
    if (typeof(v) != 'undefined')
      val(x, y, v);
    else
      return val(x, y);
  }
  this.clear = function() {
    data = new Array();
  }
  this.opCount = function(v) {
    if (typeof(v) != 'undefined')
      opCount = v;
    else
      return opCount;
  }

  // private methods
  function val(x, y, v) {
    if (typeof(v) != 'undefined')
      data[x + '_' + y] = Math.max(0.0, Math.min(1.0, v));
    else {
      if (x <= 0 || x >= size || y <= 0 || y >= size) return 0.0;

      if (data[x + '_' + y] == null) {
        opCount++;
        var base = 1;
        while (((x & base) == 0) && ((y & base) == 0))
          base <<= 1;

        if (((x & base) != 0) && ((y & base) != 0))
          squareStep(x, y, base);
        else
          diamondStep(x, y, base);
      }
      return data[x + '_' + y];
    }
  }

  function randFromPair(x, y) {
    for (var i = 0; i < 80; i++) {
      var xm7 = x % 7;
      var xm13 = x % 13;
      var xm1301081 = x % 1301081;
      var ym8461 = y % 8461;
      var ym105467 = y % 105467;
      var ym105943 = y % 105943;
      //y = (i < 40 ? seed : x);
      y = x + seed;
      x += (xm7 + xm13 + xm1301081 + ym8461 + ym105467 + ym105943);
    }

    return (xm7 + xm13 + xm1301081 + ym8461 + ym105467 + ym105943) / 1520972.0;
  }

  function displace(v, blockSize, x, y) {
    return (v + (randFromPair(x, y, seed) - 0.5) * blockSize * 2 / size * roughness);
  }

  function squareStep(x, y, blockSize) {
    if (data[x + '_' + y] == null) {
      val(x, y,
        displace((val(x - blockSize, y - blockSize) +
          val(x + blockSize, y - blockSize) +
          val(x - blockSize, y + blockSize) +
          val(x + blockSize, y + blockSize)) / 4, blockSize, x, y));
    }
  }

  function diamondStep(x, y, blockSize) {
    if (data[x + '_' + y] == null) {
      val(x, y,
        displace((val(x - blockSize, y) +
          val(x + blockSize, y) +
          val(x, y - blockSize) +
          val(x, y + blockSize)) / 4, blockSize, x, y));
    }
  }
}

function generation({seed,worldHeight=80,waterline=20}={}) {
  // Selected empirically
  var size = 10000000;
  var space = new DiamondSquare(size, size / 1000, seed);

  function generateSimpleChunk(chunkX, chunkZ) {
    var chunk = new Chunk();

    var worldX = chunkX * 16 + size / 2;
    var worldZ = chunkZ * 16 + size / 2;

    for (var x = 0; x < 16; x++) {
      for (var z = 0; z < 16; z++) {
        var level = Math.floor(space.value(worldX + x, worldZ + z) * worldHeight);
        var dirtheight = level - 4 + Math.round(Math.random()*2);
        var bedrockheight = 1 + Math.round(Math.random()*3)
        for (var y = 0; y < 256; y++) {
          let block;
          let data;

          var surfaceblock = level < waterline ? 12 : 2; // Sand below water, grass
          var belowblock = level < waterline ? 12 : 3; // 3-5 blocks below surface

          if (y < bedrockheight) block = 7; // Solid bedrock at bottom
          else if (y < level && y >= dirtheight) block = belowblock; // Dirt/sand below surface
          else if (y < level) block = 1; // Set stone inbetween
          else if (y == level) block = surfaceblock; // Set surface sand/grass
          else if (y <= waterline) block = 9; // Set the water
          else if (y == level+1 && level >= waterline && Math.random() < 0.1) { // 1/10 chance of grass
            block = 31;
            data = 1;
          }

          var pos = new Vec3(x, y, z);
          if (block) chunk.setBlockType(pos, block);
          if (data) chunk.setBlockData(pos, data);
          chunk.setSkyLight(pos, 15);
        }
      }
    }

    return chunk;
  }
  return generateSimpleChunk;
}

module.exports=generation;