index.js

import { Universe } from "wasm-game-of-life";
import { memory } from "wasm-game-of-life/wasm_game_of_life_bg";

const CELL_SIZE = 10;
const GRID_COLOR = "#000";
const DEAD_COLOR = "#000";
let ALIVE_COLOR = getRandomColor();

const canvas = document.getElementById("game-of-life-canvas");
const reset = document.getElementById("reset");
const play = document.getElementById("toggle");
const autogen = document.getElementById("auto");
const gen = document.getElementById("gen");
const toolbar = document.getElementById("tools");

const loader = document.getElementById("loading");
const ctx = canvas.getContext("2d");

let universe = Universe.new();
let epoch = 1;
let auto = false;
let stats = undefined;

const width = universe.width();
const height = universe.height();

canvas.height = (CELL_SIZE + 1) * height + 1;
canvas.width = (CELL_SIZE + 1) * width + 1;

let running = false;

function getRandomColor(minBrightness = 50) {
  while (true) {
    // Generate random integer representing a color
    const randomColor = Math.floor(Math.random() * 16777215);

    // Ensure 6-character hex string with padding
    const hexColor = "#" + randomColor.toString(16).padStart(6, "0");

    // Convert hex to RGB (ignoring alpha channel)
    const r = parseInt(hexColor.slice(1, 3), 16);
    const g = parseInt(hexColor.slice(3, 5), 16);
    const b = parseInt(hexColor.slice(5, 7), 16);

    // Calculate normalized brightness (avoiding division by zero)
    const brightness = Math.max((r + g + b) / (255 * 3), 0);

    if (brightness >= minBrightness / 100) {
      return hexColor;
    }
  }
}

function hexToRgba(hexCode, alpha = 1) {
  if (!hexCode || hexCode.length !== 7) {
    throw new Error("Invalid hex code provided.");
  }

  const r = parseInt(hexCode.slice(1, 3), 16);
  const g = parseInt(hexCode.slice(3, 5), 16);
  const b = parseInt(hexCode.slice(5, 7), 16);
  return `rgba(${r}, ${g}, ${b}, ${alpha})`;
}

const getIndex = (row, column) => {
  return row * width + column;
};

const drawCells = () => {
  const cellsPtr = universe.cells_ptr();

  // This is updated!
  const cells = new Uint8Array(memory.buffer, cellsPtr, (width * height) / 8);

  ctx.beginPath();

  for (let row = 0; row < height; row++) {
    for (let col = 0; col < width; col++) {
      const idx = getIndex(row, col);

      // This is updated!
      ctx.fillStyle = bitIsSet(idx, cells) ? ALIVE_COLOR : DEAD_COLOR;

      ctx.fillRect(
        col * (CELL_SIZE + 1) + 1,
        row * (CELL_SIZE + 1) + 1,
        CELL_SIZE,
        CELL_SIZE
      );
    }
  }

  ctx.stroke();
};

const drawGrid = () => {
  ctx.beginPath();
  ctx.strokeStyle = GRID_COLOR;

  // Vertical lines.
  for (let i = 0; i <= width; i++) {
    ctx.moveTo(i * (CELL_SIZE + 1) + 1, 0);
    ctx.lineTo(i * (CELL_SIZE + 1) + 1, (CELL_SIZE + 1) * height + 1);
  }

  // Horizontal lines.
  for (let j = 0; j <= height; j++) {
    ctx.moveTo(0, j * (CELL_SIZE + 1) + 1);
    ctx.lineTo((CELL_SIZE + 1) * width + 1, j * (CELL_SIZE + 1) + 1);
  }

  ctx.stroke();
};

const renderLoop = () => {
  if (universe.get_epoch()) {
    if (auto) {
      reset.click();
      return;
    } else {
      running = false;
      play.innerText = "run";
      updateStatus();
      return;
    }
  }

  if (!running) return;

  universe.tick();
  drawGrid();
  drawCells();
  updateStatus();
  requestAnimationFrame(renderLoop);
};

const bitIsSet = (n, arr) => {
  const byte = Math.floor(n / 8);
  const mask = 1 << n % 8;
  return (arr[byte] & mask) === mask;
};

const updateStatus = () => {
  gen.innerText = "";
  gen.innerText += `Epoch: ${epoch} ${auto ? " [auto-generated]" : ""}\n`;
  gen.innerText += `Generation: ${universe.get_gen()}\n`;
  gen.innerText += running
    ? `[running]`
    : universe.get_epoch()
    ? `[epoch expired]`
    : `[paused]\n`;
};

const wasmSupported = (() => {
  try {
    if (
      typeof WebAssembly === "object" &&
      typeof WebAssembly.instantiate === "function"
    ) {
      const module = new WebAssembly.Module(
        Uint8Array.of(0x0, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00)
      );
      if (module instanceof WebAssembly.Module)
        return new WebAssembly.Instance(module) instanceof WebAssembly.Instance;
    }
  } catch (e) {}
  return false;
})();

const pageLoaded = () => {
  while (stats === undefined) {
    stats = document.getElementById("stats");
  }

  stats.style.position = "relative";
  stats.style.border = "1px solid rgba(50, 50, 50, 0.8)";
  autogen.style.border = "1px solid rgba(225,0,0,0.5)";
  autogen.style.backgroundColor = "rgba(225,0,0,0.2)";

  /*******************************************************************************
   * Event Listeners
   *******************************************************************************/

  autogen.addEventListener("mouseover", () => {
    // Change button styles on hover

    if (auto) {
      autogen.style.border = "1px solid rgba(225,0,0,0.5)";
      autogen.style.backgroundColor = "rgba(225,0,0,0.2)";
    }
    if (!auto) {
      autogen.style.border = "1px solid rgba(0,255,0,0.5)";
      autogen.style.backgroundColor = "rgba(0,255,0,0.2)";
    }
  });

  autogen.addEventListener("mouseout", () => {
    // Change button styles back to original on mouseout
    if (!auto) {
      autogen.style.border = "1px solid rgba(225,0,0,0.5)";
      autogen.style.backgroundColor = "rgba(225,0,0,0.2)";
    }
    if (auto) {
      autogen.style.border = "1px solid rgba(0,255,0,0.5)";
      autogen.style.backgroundColor = "rgba(0,255,0,0.2)";
    }
  });

  autogen.addEventListener("click", () => {
    auto = !auto;

    updateStatus();

    if (auto) {
      autogen.style.border = "2px solid rgba(0,225,0,0.5)";
      autogen.style.backgroundColor = "rgba(0,225,0,0.2)";
    }

    if (!auto) {
      autogen.style.border = "2px solid rgba(225,0,0,0.5)";
      autogen.style.backgroundColor = "rgba(225,0,0,0.2)";
    }
  });

  reset.addEventListener("click", () => {
    console.clear();
    console.log("starting new epoch");

    universe = Universe.new();
    epoch += 1;
    ALIVE_COLOR = getRandomColor();

    toolbar.style.backgroundColor = hexToRgba(ALIVE_COLOR, 0.1);
    running = true;
    play.innerText = "pause";
    renderLoop();
  });

  play.addEventListener("click", () => {
    console.log(process.env);
    if (running) {
      play.innerText = "run";
    }

    if (!running) {
      play.innerText = "pause";
    }

    running = !running;
    renderLoop();
    updateStatus();
  });

  canvas.addEventListener("click", (event) => {
    const boundingRect = canvas.getBoundingClientRect();

    const scaleX = canvas.width / boundingRect.width;
    const scaleY = canvas.height / boundingRect.height;

    const canvasLeft = (event.clientX - boundingRect.left) * scaleX;
    const canvasTop = (event.clientY - boundingRect.top) * scaleY;

    const row = Math.min(Math.floor(canvasTop / (CELL_SIZE + 1)), height - 1);
    const col = Math.min(Math.floor(canvasLeft / (CELL_SIZE + 1)), width - 1);

    universe.toggle_cell(row, col);
    drawGrid();
    drawCells();
  });

  toolbar.style.backgroundColor = hexToRgba(ALIVE_COLOR, 0.1);

  updateStatus();
  drawGrid();
  drawCells();

  if (wasmSupported) {
    if (loader) loader.style.display = "none";
  }

  if (!wasmSupported) {
    if (loader)
      loader.innerText =
        "Webassembly not supported.\nCheck if WASM JIT is enabled or change browser!";
  }
  requestAnimationFrame(renderLoop);
};

setTimeout(pageLoaded, 100);