Initial Upload;

Runtime/Models/VolumeEntity.cs

@@ -0,0 +1,17 @@
+namespace Misaki.AoVolume
+{
+    internal readonly struct VolumeEntity
+    {
+        private const int _INVALID_INDEX = -1;
+
+        public readonly int entityIndex;
+        public readonly bool IsValid => entityIndex != _INVALID_INDEX;
+
+        public static readonly VolumeEntity InvalidEntity = new(_INVALID_INDEX);
+
+        public VolumeEntity(int index)
+        {
+            entityIndex = index;
+        }
+    }
+}