silphius/app/create-forest.js

import alea from 'alea';
import {createNoise2D} from 'simplex-noise';

import {createRandom, Generator} from '@/util/math.js';

const seed = 42069;
const prng = alea(seed);
const rawNoise = createNoise2D(prng);
const noise = (x, y) => (1 + rawNoise(x, y)) / 2;
const random = createRandom(seed);

const indexComputer = (indices, randomizer) => (
  (position) => indices[Math.floor(indices.length * randomizer(position))]
);

const [w, h] = [256, 256];

const Forest = new Generator({
  calculate: indexComputer(
    [1, 3, 4, 10, 11, 12], // grass
    ({x, y}) => noise(x * 30, y * 30),
  ),
  covers: () => true,
  size: {w, h},
  children: [
    new Generator({
      calculate: indexComputer(
        [342, 456], // dirt
        ({x, y}) => noise(x * 30, y * 30),
      ),
      covers: ({x, y}) => noise(x * (1 / 16), y * (1 / 16)) < 0.5,
      size: {w, h},
      children: [
        new Generator({
          calculate: indexComputer(
            [407, 408, 423, 424], // stone path
            ({x, y}) => noise(x * 30, y * 30),
          ),
          covers: ({x, y}) => noise(x * (1 / 16), y * (1 / 16)) < 0.1625,
          size: {w, h},
        }),
      ],
    }),
    new Generator({
      calculate: indexComputer(
        [103, 104], // water
        ({x, y}) => noise(x * 30, y * 30),
      ),
      covers: ({x, y}) => noise(x * (1 / 32), y * (1 / 32)) < 0.3,
      size: {w, h},
    }),
  ],
});

export default async function createForest() {
  const area = {x: w, y: h};
  const entities = [];
  entities.push({
    AreaSize: {x: area.x * 16, y: area.y * 16},
    Ticking: {},
    TileLayers: {
      layers: [
        {
          area,
          data: Array(w * h).fill(0),
          source: '/assets/tileset.json',
          tileSize: {x: 16, y: 16},
        },
        {
          area,
          data: Array(w * h).fill(0),
          source: '/assets/tileset.json',
          tileSize: {x: 16, y: 16},
        },
      ],
    },
    Time: {},
    Water: {},
  });
  Forest.generate();
  const master = entities[0];
  const layer0 = master.TileLayers.layers[0];
  layer0.data = Forest.matrix;
  for (let y = 0; y < h; ++y)  {
    for (let x = 0; x < w; ++x)  {
      const dirt = Forest.children[0].matrix[y * w + x];
      if (dirt) {
        layer0.data[y * w + x] = dirt;
      }
      const stone = Forest.children[0].children[0].matrix[y * w + x];
      if (stone) {
        layer0.data[y * w + x] = stone;
      }
      const water = Forest.children[1].matrix[y * w + x];
      if (water) {
        layer0.data[y * w + x] = water;
      }
    }
  }

  const entityPosition = (x, y) => ({
    x: (8 + (x * 16) + random() * 8 - 4),
    y: (8 + (y * 16) + random() * 8 - 4),
  });

  for (let y = 0; y < h; ++y) {
    for (let x = 0; x < w; ++x) {
      let v = noise(x * (1 / 24), y * (1 / 24));
      if (v > 0.2) {
        v = noise(x * (1 / 7), y * (1 / 7));
        if (v < 0.15) {
          entities.push({
            Position: entityPosition(x, y),
            Sprite: {
              anchorY: 0.7,
              source: '/assets/ambient/shrub.json',
            },
            VisibleAabb: {},
          });
        }
        else if (v < 0.17) {
          entities.push({
            Position: entityPosition(x, y),
            Sprite: {
              anchorY: 0.875,
              source: '/assets/ambient/tree.json',
            },
            VisibleAabb: {},
          });
        }
        v = noise(x * (1 / 12), y * (1 / 12));
        if (v < 0.08) {
          entities.push({
            Position: entityPosition(x, y),
            Sprite: {
              anchorY: 0.7,
              source: '/assets/ambient/flower.json',
            },
            VisibleAabb: {},
          });
        }
      }
    }
  }
  return entities;
}