From a324d52df5a489ae82d8b21772f2d51581fed7be Mon Sep 17 00:00:00 2001
From: Marty Oehme <marty.oehme@gmail.com>
Date: Thu, 30 Aug 2018 12:03:23 +0200
Subject: [PATCH] Fix Simulation Neighbor Propagation

---
 lib/src/Simulation.dart | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/lib/src/Simulation.dart b/lib/src/Simulation.dart
index 7f221ba..ca7bb71 100644
--- a/lib/src/Simulation.dart
+++ b/lib/src/Simulation.dart
@@ -23,11 +23,14 @@ class Simulation {
   int get w => map.width;
   int get h => map.height;
 
-  Simulation(int w, int h) : this.map = new Grid.fill(w, h, _getGOLCell()) {
+  Simulation(int w, int h) : this.map = new Grid(w, h) {
+    for (int i = 0; i < map.length; i++) {
+      map[i] = _getGOLCell();
+    }
     print("Grid creation finished");
   }
 
-  static Cell _getGOLCell([bool defaultState = false]) {
+  Cell _getGOLCell([bool defaultState = false]) {
     Cell cell = Cell(defaultState);
     Rule threeTrue = new Rule((int n) {
       if (n == 3) return true;
@@ -37,8 +40,9 @@ class Simulation {
       if (n == 2) return true;
       return false;
     });
-    cell.surviveRules..add(twoTrue)..add(threeTrue);
-    cell.birthRules.add(twoTrue);
+    cell.surviveRules.add(twoTrue);
+    cell.surviveRules.add(threeTrue);
+    cell.birthRules.add(threeTrue);
     return cell;
   }
 
@@ -133,21 +137,20 @@ class Simulation {
       if (el.state != el.nextState) stateChanges = true;
       el.advanceState();
     });
+    stateChanges ? _dirty = true : false;
     return stateChanges;
   }
 
   int getSurroundingNeighbors(int x, int y, int range) {
     int count = 0;
-    for (int iy = y - range; iy <= y + range; iy++) {
-      for (int ix = x - range; ix <= x + range; ix++) {
-        if (ix > 0 &&
-            iy > 0 &&
-            iy < map.height &&
+    for (int ix = -range + x; ix <= range + x; ix++) {
+      for (int iy = -range + y; iy <= range + y; iy++) {
+        if (ix >= 0 &&
+            iy >= 0 &&
             ix < map.width &&
-            map.get(x, y).state == true &&
-            !(x == ix && y == iy)) {
-          count++;
-        }
+            iy < map.height &&
+            map.get(ix, iy).state == true &&
+            !(x == ix && y == iy)) count++;
       }
     }
     return count;
@@ -161,8 +164,7 @@ class Simulation {
     int brickW = (canvas.width ~/ map.width);
     int brickH = (canvas.height ~/ map.height);
     ctx.clearRect(0, 0, canvas.width, canvas.height);
-
-    for (int i; i < map.length; i++) {
+    for (int i = 0; i < map.length; i++) {
       math.Point p = map.toCoordinates(i);
       if (_renderEdges) {
         ctx.setStrokeColorRgb(100, 100, 100);
@@ -175,7 +177,6 @@ class Simulation {
         ctx.setFillColorRgb(0, 0, 0);
       ctx.fillRect(p.x * brickW, p.y * brickH, brickW, brickH);
     }
-
     _dirty = false;
   }