fix(game): implement spawn probability

src/CorePluginAPI/Game/World/SpawnGroup.cs

@@ -4,10 +4,15 @@ public class SpawnMember
     {
         public uint Id { get; init; }
     }
+
     public class SpawnGroupCollectionMember
     {
         public uint Id { get; init; }
-        public byte Amount { get; init; }
+
+        /// <summary>
+        /// 0 to 1 probability of spawning
+        /// </summary>
+        public float Probability { get; set; }
     }
 
     public class SpawnGroup

src/Libraries/Game.Server/Extensions/ParserExtensions.cs

@@ -11,10 +11,7 @@ public static SpawnGroup ToSpawnGroup(this ParserService.DataFileGroup group)
         {
             Id = group.GetField<uint>("Vnum"),
             Leader = group.GetField<uint>("Leader"),
-            Members = group.Data.Select(data => new SpawnMember
-            {
-                Id = uint.Parse(data.LastOrDefault()!)
-            }).ToList(),
+            Members = group.Data.Select(data => new SpawnMember {Id = uint.Parse(data.LastOrDefault()!)}).ToList(),
             Name = group.Name
         };
     }
@@ -25,11 +22,13 @@ public static SpawnGroupCollection ToSpawnGroupCollection(this ParserService.Dat
         {
             Id = group.GetField<uint>("Vnum"),
             Name = group.Name,
-            Groups = group.Data.Select(data => new SpawnGroupCollectionMember
+            Groups = group.Data.Select(data =>
             {
-                Id = uint.Parse(data[1]),
-                Amount = byte.TryParse(data.ElementAtOrDefault(2), out var amount) ? amount : (byte) 1
+                var p = byte.TryParse(data.ElementAtOrDefault(2), out var probability) && probability > 1
+                    ? (float)(probability / 100m)
+                    : 1;
+                return new SpawnGroupCollectionMember {Id = uint.Parse(data[1]), Probability = p};
             }).ToList()
         };
     }
-}
+}

src/Libraries/Game.Server/World/Map.cs

@@ -53,7 +53,7 @@
         private readonly IItemManager _itemManager;
         private readonly IServerBase _server;
 
         public Map(IMonsterManager monsterManager, IAnimationManager animationManager, ICacheManager cacheManager,
             IWorld world, ILogger logger, ISpawnPointProvider spawnPointProvider,
             IDropProvider dropProvider, IItemManager itemManager, IServerBase server, string name, Coordinates position,
             uint width, uint height, TownCoordinates? townCoordinates)
@@ -80,9 +80,7 @@
                     Shinsoo = Position + townCoordinates.Shinsoo * SPAWN_POSITION_MULTIPLIER,
                     Common = Position + townCoordinates.Common * SPAWN_POSITION_MULTIPLIER
                 }
-                : null;
-            _quadTree = new QuadTree((int)position.X, (int)position.Y, (int)(width * MapUnit), (int)(height * MapUnit),
-                20);
+                : null;            _quadTree = new QuadTree((int)position.X, (int)position.Y, (int)(width * MapUnit), (int)(height * MapUnit), 20);
             _entityGauge = GameServer.Meter.CreateObservableGauge($"Map:{name}:EntityCount", () => Entities.Count);
         }
 
@@ -237,7 +235,15 @@
                         var group = _world.GetGroup(collectionGroup.Id);
                         if (group != null)
                         {
-                            for (var i = 0; i < collectionGroup.Amount; i++)
+                            if (collectionGroup.Probability < 1)
+                            {
+                                var rand = Random.Shared.NextSingle();
+                                if (rand > collectionGroup.Probability)
+                                {
+                                    SpawnGroup(groupInstance, spawnPoint, group);
+                                }
+                            }
+                            else
                             {
                                 SpawnGroup(groupInstance, spawnPoint, group);
                             }

src/Tests/Core.Tests/MapTests.cs

@@ -78,13 +78,13 @@ public MapTests(ITestOutputHelper testOutputHelper)
                     {
                         Id = 101,
                         Name = "TestGroupCollection",
-                        Groups = {new SpawnGroupCollectionMember {Id = 101, Amount = 1}}
+                        Groups = {new SpawnGroupCollectionMember {Id = 101, Probability = 1}}
                     },
                     new SpawnGroupCollection
                     {
                         Id = 101,
                         Name = "TestGroupCollection",
-                        Groups = {new SpawnGroupCollectionMember {Id = 101, Amount = 1}}
+                        Groups = {new SpawnGroupCollectionMember {Id = 101, Probability = 1}}
                     }
                 });
                 return mock;