Refactored GameObject to Entity, replaced @x,@y,@z with @position, added @velocity vector to Entity, bricked Player terrain interaction while authoring Axis Aligned Bounding Box Tree for CollisionManager to handle all collision interaction. Added PhysicsManager stub.

lib/managers/entity_manager.rb

@@ -0,0 +1,28 @@
+class IMICFPS
+  TextureCoordinate = Struct.new(:u, :v, :weight)
+  Point = Struct.new(:x, :y)
+  Color = Struct.new(:red, :green, :blue, :alpha)
+
+  module EntityManager # Get included into GameState context
+    def add_entity(entity)
+      @collision_manager.add(entity) if entity.collidable?
+      @entities << entity
+    end
+
+    def find_entity(entity)
+      @entities.detect {|entity| entity == entity}
+    end
+
+    def remove_entity(entity)
+      ent = @entities.detect {|entity| entity == entity}
+      if ent
+        @collision_manager.remove(entity)
+        @entities.delete(ent)
+      end
+    end
+
+    def entities
+      @entities
+    end
+  end
+end