Allow Switching between Random and Ordered Rectangle Updates

lib/game/Game.dart

@@ -13,6 +13,9 @@ class Game {
   bool _oscillDir = true; // oscillate upwards (true) or downwards (false)
   double _OSCILLSPEED = 1.0;
   bool _fwd = true;
+  Point _curPos = Point(-1, 0);
+
+  bool isRandom = false;
 
   Game(CanvasElement this.canvas) {
     grid = _buildGrid(5, new Color(255, 255, 255));
@@ -20,8 +23,24 @@ class Game {
 
   // In-World Logic Updates
   void update([num dt]) {
+    Point next = isRandom ? nextPosRandom() : nextPosOrdered(_curPos);
+    print(_curPos.toString());
+    grid[next.y][next.x] =
+        new Color(rng.nextInt(255), rng.nextInt(255), rng.nextInt(255));
+    _curPos = next;
+  }
+
+  Point nextPosOrdered(Point curPos) {
+    Point pos = Point(curPos.x, curPos.y);
+    if (pos.x >= grid[pos.y].length - 1) pos = Point(-1, pos.y + 1);
+    if (pos.y >= grid.length) pos = Point(-1, 0);
+    pos = Point(pos.x + 1, pos.y);
+    return pos;
+  }
+
+  Point nextPosRandom() {
     int ry = rng.nextInt(grid.length);
-    grid[ry][rng.nextInt(grid[ry].length)] = new Color(rng.nextInt(255), rng.nextInt(255), rng.nextInt(255));
+    return Point(rng.nextInt(grid[ry].length), ry);
   }
 
   // Render Pipeline
@@ -40,7 +59,7 @@ class Game {
 
     // This should usually be place in update()
     // Placed here to highlight render speed changes for some examples
-    // See dirty flag Loop for details
+    // See variable timestep & dirty flag Loops for details
     _oscillate();
   }
 
@@ -89,6 +108,10 @@ class Game {
       this.grid = _buildGrid(grid.length + 5, Color(255, 255, 255));
     }
   }
+
+  void toggleRandomOrder() {
+    isRandom = !isRandom;
+  }
 }
 
 class Color {