From f6fa2759a6dce5379554d7294f00487bb1565004 Mon Sep 17 00:00:00 2001
From: Jean-Marie Mineau <jean-marie.mineau@protonmail.com>
Date: Fri, 14 May 2021 00:10:37 +0200
Subject: [PATCH] use a more compact memory rep

---
 index.js | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/index.js b/index.js
index 090aeef..0d5f7cc 100644
--- a/index.js
+++ b/index.js
@@ -7,7 +7,13 @@ const GRID_COLOR = "#444444";
 const DEAD_COLOR = "#000000";
 const ALIVE_COLOR = "#FFFFFF";
 
-const universe = Universe.new_space_ship();
+const seed = Math.random();
+const universe = ((seed) => {
+    if (seed < 1/3) return Universe.new();
+    else if (seed < 2/3) return  Universe.new_random();
+    else return Universe.new_space_ship();
+})(seed);
+
 const width = universe.width();
 const height = universe.height();
 
@@ -59,7 +65,7 @@ const getIndex = (row, column) => {
 
 const drawCells = () => {
   const cellsPtr = universe.cells();
-  const cells = new Uint8Array(memory.buffer, cellsPtr, width * height);
+  const cells = new Uint8Array(memory.buffer, cellsPtr, width * height / 8);
 
   ctx.beginPath();
 
@@ -67,9 +73,9 @@ const drawCells = () => {
     for (let col = 0; col < width; col++) {
       const i = getIndex(row, col);
 
-      ctx.fillStyle = cells[i] === Cell.Dead
-        ? DEAD_COLOR
-        : ALIVE_COLOR;
+      ctx.fillStyle = bitIsSet(i, cells)
+        ? ALIVE_COLOR
+        : DEAD_COLOR;
 
       ctx.fillRect(
         col * (CELL_SIZE + 1) + 1,
@@ -83,4 +89,10 @@ const drawCells = () => {
   ctx.stroke();
 }
 
+const bitIsSet = (n, arr) => {
+  const byte = Math.floor(n / 8);
+  const mask = 1 << (n % 8);
+  return (arr[byte] & mask) === mask;
+}
+
 requestAnimationFrame(renderLoop);