fix some errata

content/pong/draw_paddle/texture_renderer.md

@@ -18,7 +18,7 @@ namespace PongFE.Renderers
 {
     public class Texture2DRenderer : OrderedRenderer<Texture2DComponent>
     {
-        public override void Render(Entity entity, in Texture2DComponent drawComponent)
+        public override void Render(Entity entity, in Texture2DComponent textureComponent)
         {
 
         }
@@ -46,6 +46,7 @@ Now let's fill out the Renderer some more.
 
 ```cs
 using Encompass;
+using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 using PongFE.Components;
 
@@ -118,6 +119,10 @@ When we define a method in this way, it means that we can add a new method to an
 Now we can rewrite our SpriteBatch draw call:
 
 ```cs
+using PongFE.Extensions;
+
+...
+
     _spriteBatch.Draw(
         textureComponent.Texture,
         positionComponent.Position.ToXNAVector(),

content/pong/move_paddle/input_handling.md

@@ -17,6 +17,8 @@ using Encompass;
 using Microsoft.Xna.Framework.Input;
 using PongFE.Messages;
 
+namespace PongFE.Engines
+{
     public class InputEngine : Engine
     {
         public override void Update(double dt)
@@ -29,6 +31,7 @@ public class InputEngine : Engine
             }
         }
     }
+}
 ```
 
 *record scratch*

content/pong/move_paddle/motion_engine.md

@@ -11,6 +11,8 @@ Create a file: **PongFE/Engines/MotionEngine.cs**
 ```cs
 using Encompass;
 
+namespace PongFE.Engines
+{
     public class MotionEngine : Engine
     {
         public override void Update(double dt)
@@ -18,6 +20,7 @@ public class MotionEngine : Engine
 
         }
     }
+}
 ```
 
 Every Engine must implement an *Update* method, which takes a *delta-time* value as a parameter.
@@ -78,6 +81,12 @@ namespace PongFE.Engines
 }
 ```
 
+Let's add this engine to the WorldBuilder.
+
+```cs
+WorldBuilder.AddEngine(new MotionEngine());
+```
+
 If we run the game right now, Encompass will yell at us. Why? Because it can't guarantee that this Engine runs after Engines which *send* MotionMessages, which is no good. So we need to declare what is called a *class attribute* on the Engine. We'll talk about sending messages soon. But for now, we need to let Encompass know that this Engine will be receiving MotionMessages with a *Receives* attribute.
 
 ```cs
@@ -165,11 +174,10 @@ namespace PongFE.Engines
 }
 ```
 
-Before we move on any farther, let's make sure to add this Engine to our WorldBuilder.
+Before we move on any farther, let's make sure to add this Renderer to our WorldBuilder.
 
 ```cs
     ...
-    WorldBuilder.AddEngine(new MotionEngine());
     WorldBuilder.AddOrderedRenderer(new Texture2DRenderer(SpriteBatch));
     ...
 ```