From 57fb02daf2fda6ed400a150c9a25e02213a59576 Mon Sep 17 00:00:00 2001
From: Evan Hemsley <evan@moonside.games>
Date: Mon, 27 Jul 2020 14:12:47 -0700
Subject: [PATCH] add update method to code blocks for clarity

---
 content/pong/ball/bouncing/motion_engine.md | 101 ++++++++++----------
 1 file changed, 52 insertions(+), 49 deletions(-)

diff --git a/content/pong/ball/bouncing/motion_engine.md b/content/pong/ball/bouncing/motion_engine.md
index 2a56404..4e0e205 100644
--- a/content/pong/ball/bouncing/motion_engine.md
+++ b/content/pong/ball/bouncing/motion_engine.md
@@ -81,28 +81,28 @@ Next, in a separate block, let's consolidate our MotionMessages per Entity.
 
     private readonly Dictionary<Entity, Vector2> _moveAmounts = new Dictionary<Entity, Vector2>();
 
-    ...
-
-    _spatialHash.Clear();
-    _moveAmounts.Clear();
-
-    foreach (var entity in TrackedEntities)
+    public override void Update(double dt)
     {
-        ...
-    }
+        _spatialHash.Clear();
+        _moveAmounts.Clear();
 
-    foreach (ref readonly var entity in ReadEntities<PositionComponent>())
-    {
-        ref readonly var positionComponent = ref GetComponent<PositionComponent>(entity);
-
-        _moveAmounts[entity] = Vector2.Zero;
-        foreach (var motionMessage in ReadMessagesWithEntity<MotionMessage>(entity))
+        foreach (var entity in TrackedEntities)
         {
-            _moveAmounts[entity] += motionMessage.Movement;
+            ...
         }
-    }
 
-    ...
+        foreach (ref readonly var entity in ReadEntities<PositionComponent>())
+        {
+            ref readonly var positionComponent = ref GetComponent<PositionComponent>(entity);
+
+            _moveAmounts[entity] = Vector2.Zero;
+            foreach (var motionMessage in ReadMessagesWithEntity<MotionMessage>(entity))
+            {
+                _moveAmounts[entity] += motionMessage.Movement;
+            }
+        }
+
+        ...
 ```
 
 This is where our *IHasEntity* optimization comes in. It allows us to use the **ReadMessagesWithEntity** method. This method efficiently queries messages that refer to the given entity.
@@ -236,45 +236,48 @@ namespace PongFE.Engines
 Now, in the final block of our **MotionEngine**, we can perform our collision tests and send out our messages.
 
 ```cs
-    ...
-
-    foreach (var entity in TrackedEntities)
+    public override void Update(double dt)
     {
         ...
-    }
 
-    foreach (ref readonly var entity in ReadEntities<PositionComponent>())
-    {
-        ...
-    }
-
-    foreach (var entity in TrackedEntities)
-    {
-        Vector2 moveAmount = _moveAmounts[entity];
-
-        ref readonly var positionComponent = ref GetComponent<PositionComponent>(entity);
-        var projectedPosition = positionComponent.Position + moveAmount;
-
-        ref readonly var collisionComponent = ref GetComponent<CollisionComponent>(entity);
-        var rectangle = collisionComponent.Rectangle;
-        var (xHit, yHit, newPosition, collisionEntity) = SolidCollisionPosition(rectangle, positionComponent.Position, projectedPosition);
-
-        if (xHit || yHit)
+        foreach (var entity in TrackedEntities)
         {
-            projectedPosition = newPosition;
-
-            if (xHit)
-            {
-                SendMessage(new CollisionMessage(entity, collisionEntity, HitOrientation.Horizontal));
-            }
-            else
-            {
-                SendMessage(new CollisionMessage(entity, collisionEntity, HitOrientation.Vertical));
-            }
+            ...
         }
 
+        foreach (ref readonly var entity in ReadEntities<PositionComponent>())
+        {
+            ...
+        }
 
-        SendMessage(new UpdatePositionMessage(entity, projectedPosition));
+        foreach (var entity in TrackedEntities)
+        {
+            Vector2 moveAmount = _moveAmounts[entity];
+
+            ref readonly var positionComponent = ref GetComponent<PositionComponent>(entity);
+            var projectedPosition = positionComponent.Position + moveAmount;
+
+            ref readonly var collisionComponent = ref GetComponent<CollisionComponent>(entity);
+            var rectangle = collisionComponent.Rectangle;
+            var (xHit, yHit, newPosition, collisionEntity) = SolidCollisionPosition(rectangle, positionComponent.Position, projectedPosition);
+
+            if (xHit || yHit)
+            {
+                projectedPosition = newPosition;
+
+                if (xHit)
+                {
+                    SendMessage(new CollisionMessage(entity, collisionEntity, HitOrientation.Horizontal));
+                }
+                else
+                {
+                    SendMessage(new CollisionMessage(entity, collisionEntity, HitOrientation.Vertical));
+                }
+            }
+
+
+            SendMessage(new UpdatePositionMessage(entity, projectedPosition));
+        }
     }
 ```