misc optimization & refactoring

Subsurface/Source/Characters/BackgroundSprite/BackgroundSprite.cs

@@ -15,6 +15,8 @@ namespace Subsurface
 
         const float CheckWallsInterval = 5.0f;
 
+        public bool Enabled;
+
         private BackgroundSpritePrefab prefab;
 
         private Vector2 position;
@@ -29,6 +31,12 @@ namespace Subsurface
 
         public Swarm Swarm;
 
+        Vector2 drawPosition;
+        public Vector2 TransformedPosition
+        {
+            get { return drawPosition; }
+        }
+
         public Vector2 Position
         {
             get { return position; }
@@ -51,6 +59,8 @@ namespace Subsurface
 
             this.position = position;
 
+            drawPosition = position + Level.Loaded.Position;
+
             steeringManager = new SteeringManager(this);
 
             velocity = new Vector3(
@@ -141,18 +151,16 @@ namespace Subsurface
                 if (velocity.X < 0.0f) rotation -= MathHelper.Pi;
             }
 
-            Vector2 drawPos = position;
-
-            if (Level.Loaded != null) drawPos += Level.Loaded.Position;
+            if (Level.Loaded != null) drawPosition = position + Level.Loaded.Position;
 
             if (depth > 0.0f)
             {
-                Vector2 camOffset = drawPos - GameMain.GameScreen.Cam.WorldViewCenter;
+                Vector2 camOffset = drawPosition - GameMain.GameScreen.Cam.WorldViewCenter;
 
-                drawPos = drawPos - camOffset * (depth / MaxDepth) * 0.05f;
+                drawPosition = drawPosition - camOffset * (depth / MaxDepth) * 0.05f;
             }
 
-            prefab.Sprite.Draw(spriteBatch, new Vector2(drawPos.X, -drawPos.Y), Color.Lerp(Color.White, Color.DarkBlue, (depth/MaxDepth)*0.3f),
+            prefab.Sprite.Draw(spriteBatch, new Vector2(drawPosition.X, -drawPosition.Y), Color.Lerp(Color.White, Color.DarkBlue, (depth/MaxDepth)*0.3f),
                 rotation, 1.0f - (depth / MaxDepth) * 0.2f, velocity.X > 0.0f ? SpriteEffects.None : SpriteEffects.FlipHorizontally, (depth / MaxDepth));
         }
     }

Subsurface/Source/Characters/BackgroundSprite/BackgroundSpriteManager.cs

@@ -12,6 +12,10 @@ namespace Subsurface
     {
         const int MaxSprites = 100;
 
+        const float checkActiveInterval = 1.0f;
+
+        float checkActiveTimer;
+
         private List<BackgroundSpritePrefab> prefabs;
         private List<BackgroundSprite> activeSprites;
 
@@ -31,7 +35,6 @@ namespace Subsurface
 
         public void SpawnSprites(int count)
         {
-
             activeSprites.Clear();
 
             if (prefabs.Count == 0) return;
@@ -77,10 +80,26 @@ namespace Subsurface
             activeSprites.Clear();
         }
 
-        public void Update(float deltaTime)
+        public void Update(Camera cam, float deltaTime)
         {
+            if (checkActiveTimer<0.0f)
+            {
+                foreach (BackgroundSprite sprite in activeSprites)
+                {
+                    sprite.Enabled = (Math.Abs(sprite.TransformedPosition.X - cam.WorldViewCenter.X) < 4000.0f &&
+                    Math.Abs(sprite.TransformedPosition.Y - cam.WorldViewCenter.Y) < 4000.0f);                    
+                }
+
+                checkActiveTimer = checkActiveInterval;
+            }
+            else
+            {
+                checkActiveTimer -= deltaTime;
+            }
+
             foreach (BackgroundSprite sprite in activeSprites)
             {
+                if (!sprite.Enabled) continue;
                 sprite.Update(deltaTime);
             }
         }
@@ -89,6 +108,7 @@ namespace Subsurface
         {
             foreach (BackgroundSprite sprite in activeSprites)
             {
+                if (!sprite.Enabled) continue;
                 sprite.Draw(spriteBatch);
             }
         }