Log when two layers use the same priority

Assets.Scripts.Core.Scene/Layer.cs

@@ -1,4 +1,5 @@
 using Assets.Scripts.Core.AssetManagement;
+using MOD.Scripts.Core;
 using MOD.Scripts.Core.Scene;
 using System.Collections;
 using System.IO;
@@ -651,6 +652,22 @@ public void SetPriority(int newpriority)
 			Vector3 localPosition2 = base.transform.localPosition;
 			targetPosition = new Vector3(x, localPosition2.y, (float)Priority * -0.1f);
 			base.transform.localPosition = targetPosition;
+
+			try
+			{
+				if (GameSystem.Instance.SceneController.PriorityInUseByOtherLayer(this, out int layerUsingPriority, out int thisLayerNumber))
+				{
+					// In-engine "Priority" is 1 higher than the priority you specify in the game script.
+					MODLogger.Log(
+						$"WARNING: Attempted to use [Layer {thisLayerNumber}] with priority {Priority - 1}, " +
+						$"but [Layer {layerUsingPriority}] is already using priority {Priority - 1}. " +
+						$"This layer may not be drawn correctly/graphical artifacts may occur.", true);
+				}
+			}
+			catch (System.Exception e)
+			{
+				MODLogger.Log($"Error while checking Layer Priority: {e}", true);
+			}
 		}
 
 		public void FadeInLayer(float time)

Assets.Scripts.Core.Scene/SceneController.cs

@@ -119,6 +119,44 @@ public void RemoveLayerReference(Layer l)
 			}
 		}
 
+		public bool PriorityInUseByOtherLayer(Layer layerToCheck, out int layerUsingPriority, out int layerToCheckNumber)
+		{
+			layerToCheckNumber = -1;
+			layerUsingPriority = -1;
+
+			for (int id = 0; id < layers.Length; id++)
+			{
+				if (layers[id] == null)
+				{
+					continue;
+				}
+
+				if (LayerPool.IsInPool(layers[id].gameObject))
+				{
+					continue;
+				}
+
+				if (!layers[id].IsInUse)
+				{
+					continue;
+				}
+
+				// Don't check layer against itself
+				if (layers[id].gameObject == layerToCheck.gameObject)
+				{
+					layerToCheckNumber = id;
+					continue;
+				}
+
+				if (layers[id].Priority == layerToCheck.Priority)
+				{
+					layerUsingPriority = id;
+				}
+			}
+
+			return layerUsingPriority != -1;
+		}
+
 		public int GetActiveLayerMask()
 		{
 			if (activeScene == 0)