Simple MapEntity visibility culling (structures outside the camera view or items with nothing to render aren't drawn)

Could be optimized further, but already gives a pretty nice performance boost

Subsurface/Source/Map/MapEntity.cs

@@ -319,6 +319,11 @@ namespace Barotrauma
             mapEntityList.Insert(i, this);
         }
 
+        public virtual bool IsVisible(Rectangle worldView)
+        {
+            return true;
+        }
+
         public virtual void Draw(SpriteBatch spriteBatch, bool editing, bool back=true) {}
 
         public virtual void DrawDamage(SpriteBatch spriteBatch, Effect damageEffect) {}

Subsurface/Source/Map/Structure.cs

@@ -475,6 +475,15 @@ namespace Barotrauma
             if (convexHulls != null) convexHulls.ForEach(x => x.Remove());
         }
 
+        public override bool IsVisible(Rectangle WorldView)
+        {
+            Rectangle worldRect = WorldRect;
+
+            if (worldRect.X > WorldView.Right || worldRect.Right < WorldView.X) return false;
+            if (worldRect.Y < WorldView.Y - WorldView.Height || worldRect.Y - worldRect.Height > WorldView.Y) return false;
+
+            return true;
+        }
 
         public override void Draw(SpriteBatch spriteBatch, bool editing, bool back = true)
         {
@@ -514,7 +523,7 @@ namespace Barotrauma
                         spriteBatch,
                         new Vector2(rect.X + drawOffset.X, -(rect.Y + drawOffset.Y)),
                         new Vector2(rect.Width, rect.Height),
-                        Vector2.Zero, color, Point.Zero);
+                        color, Point.Zero);
                 }
             }
 
@@ -553,7 +562,7 @@ namespace Barotrauma
                         spriteBatch,
                         new Vector2(sections[i].rect.X + drawOffset.X, -(sections[i].rect.Y + drawOffset.Y)),
                         new Vector2(sections[i].rect.Width, sections[i].rect.Height),
-                        Vector2.Zero, color,
+                        color,
                         textureOffset, depth);
                 }
             }

Subsurface/Source/Map/Submarine.cs

@@ -289,10 +289,10 @@ namespace Barotrauma
         }
 
         //drawing ----------------------------------------------------
-        
+
         public static void CullEntities(Camera cam)
         {
-            List<Submarine> visibleSubs = new List<Submarine>();
+            HashSet<Submarine> visibleSubs = new HashSet<Submarine>();
             foreach (Submarine sub in Submarine.Loaded)
             {
                 Rectangle worldBorders = new Rectangle(
@@ -301,19 +301,20 @@ namespace Barotrauma
                     sub.Borders.Width + 1000,
                     sub.Borders.Height + 1000);
 
-
                 if (Submarine.RectsOverlap(worldBorders, cam.WorldView))
                 {
                     visibleSubs.Add(sub);
                 }
             }
 
+            Rectangle worldView = cam.WorldView;
+
             visibleEntities = new List<MapEntity>();
             foreach (MapEntity me in MapEntity.mapEntityList)
             {
                 if (me.Submarine == null || visibleSubs.Contains(me.Submarine))
                 {
-                    visibleEntities.Add(me);
+                    if (me.IsVisible(worldView)) visibleEntities.Add(me);
                 }
             }
         }