1 files changed, 13 insertions, 1 deletions
diff --git a/src/simulation/lattice_rules.js b/src/simulation/lattice_rules.js
index db027a3..80f3221 100644
--- a/src/simulation/lattice_rules.js
+++ b/src/simulation/lattice_rules.js
@@ -53,7 +53,19 @@ export const lattice_rules = {
     }
   },
 
-  mutable: () => {},
+  mutable: (lattice, x, y) => {
+    const num_active_neighbors = neighbors(lattice, x, y)
+      .map(([x, y, cell]) => cell.type)
+      .filter(type => type === 'active')
+      .length;
+    if (num_active_neighbors > 0) {
+      // become living cell
+      return { world_updates: [{ 
+        x, y, from: 'empty', to: 'active',
+        flags: { emit: [0, 0, 0, 0, 0, 0, 0, 1] },
+      }]};
+    }
+  },
   immutable: () => {},
   flag: () => {},