Add LOD cross-fade support, null safety, and consistent LODGroup initialization

CHANGELOG.md

@@ -4,6 +4,19 @@ All notable changes to this package will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## 0.2.0 - 2026-03-11
+### Added
+- LOD fade mode support (None, CrossFade, SpeedTree) to reduce popping artifacts during LOD transitions
+- Animate cross-fading toggle for smooth automated LOD blending
+- `LODGroupHelper.InvalidateCache()` method for manual cache refresh after external LODGroup changes
+- Fade mode settings exposed in Preferences UI, per-model LODData overrides, and LODData inspector
+
+### Fixed
+- Consistent `ForceLOD(0)/ForceLOD(-1)` initialization pattern in `ModelImporterLODGenerator.CreateLODGroup`
+- Null renderer filtering when building LOD arrays for LODGroup setup in `ModelImporterLODGenerator`
+- Null safety for renderer arrays in `Extensions.HasLODChain()`
+- Null safety for LOD arrays and renderer arrays in `LODGroupExtensions.SetRenderersEnabled`
+
 ## 0.1.2 - 2024-05-23
 - Adds option to use same material for all LODs
 - More Instalod integration fixes

Editor/AutoLOD.cs

@@ -114,6 +114,8 @@ static public void GenerateLODs(GameObject go)
                 lodGroup.ForceLOD(0);
                 lodGroup.SetLODs(lods.ToArray());
                 lodGroup.RecalculateBounds();
+                lodGroup.fadeMode = autoLODSettingsData.FadeMode;
+                lodGroup.animateCrossFading = autoLODSettingsData.AnimateCrossFading;
                 lodGroup.ForceLOD(-1);
 
                 var prefab = PrefabUtility.GetCorrespondingObjectFromSource(go);

Editor/AutoLODSettings.cs

@@ -34,6 +34,7 @@ static void DisplayPreferencesGUI()
             GenerateLODsOnImportGUI();
             SaveAssetsGUI();
             SameMaterialLODsGUI();
+            FadeModeGUI();
             UseSceneLODGUI();
             HierarchyTypeGUI();
             ParentNameGUI();
@@ -180,6 +181,30 @@ static void SameMaterialLODsGUI()
                 autoLODSettingsData.UseSameMaterialForLODs = useSameMaterial;
         }
 
+        static void FadeModeGUI()
+        {
+            var label = new GUIContent("LOD Fade Mode", "Controls how LOD levels transition. "
+                                                        + "None uses hard cuts between LODs. CrossFade enables blending between LOD levels "
+                                                        + "to reduce popping artifacts. SpeedTree is optimized for SpeedTree assets.");
+
+            EditorGUI.BeginChangeCheck();
+            var fadeModeValue = (LODFadeMode)EditorGUILayout.EnumPopup(label, autoLODSettingsData.FadeMode);
+            if (EditorGUI.EndChangeCheck())
+                autoLODSettingsData.FadeMode = fadeModeValue;
+
+            if (autoLODSettingsData.FadeMode != LODFadeMode.None)
+            {
+                EditorGUI.indentLevel++;
+                var animateLabel = new GUIContent("Animate Cross-Fading", "When enabled, Unity will automatically "
+                                                                          + "animate the transition between LOD levels over time for smoother visual results.");
+                EditorGUI.BeginChangeCheck();
+                var animate = EditorGUILayout.Toggle(animateLabel, autoLODSettingsData.AnimateCrossFading);
+                if (EditorGUI.EndChangeCheck())
+                    autoLODSettingsData.AnimateCrossFading = animate;
+                EditorGUI.indentLevel--;
+            }
+        }
+
         static void UseSceneLODGUI()
         {
             var label = new GUIContent("Scene LOD", "Enable Hierarchical LOD (HLOD) support for scenes, "

Editor/Extensions.cs

@@ -14,7 +14,7 @@ public static bool HasLODChain(this LODGroup lodGroup)
                     for (var l = 1; l < lods.Length; l++)
                     {
                         var lod = lods[l];
-                        if (lod.renderers.Length > 0)
+                        if (lod.renderers != null && lod.renderers.Length > 0)
                         {
                             return true;
                         }

Editor/LODDataEditor.cs

@@ -41,6 +41,8 @@ public override void OnInspectorGUI()
                 m_ImportSettings.FindPropertyRelative("initialLODMaxPolyCount").intValue = autoLODSettingsData.InitialLODMaxPolyCount;
                 m_ImportSettings.FindPropertyRelative("hierarchyType").enumValueIndex = (int)autoLODSettingsData.HierarchyType;
                 m_ImportSettings.FindPropertyRelative("parentName").stringValue = autoLODSettingsData.ParentName;
+                m_ImportSettings.FindPropertyRelative("fadeMode").enumValueIndex = (int)autoLODSettingsData.FadeMode;
+                m_ImportSettings.FindPropertyRelative("animateCrossFading").boolValue = autoLODSettingsData.AnimateCrossFading;
             }
 
             if (settingsOverridden)

Editor/ModelImporterLODGenerator.cs

@@ -464,12 +464,20 @@ void CreateLODGroup(GameObject go, LODData lodData)
 
             for (int i = 0; i <= maxLODFound; i++)
             {
-                var lod = new LOD { renderers = lodData[i], screenRelativeTransitionHeight = GetScreenPercentage(i, maxLODFound, importerLODLevels) };
+                var renderers = lodData[i];
+                if (renderers != null)
+                    renderers = renderers.Where(r => r != null).ToArray();
+
+                var lod = new LOD { renderers = renderers ?? Array.Empty<Renderer>(), screenRelativeTransitionHeight = GetScreenPercentage(i, maxLODFound, importerLODLevels) };
                 lods.Add(lod);
             }
 
+            lodGroup.ForceLOD(0);
             lodGroup.SetLODs(lods.ToArray());
             lodGroup.RecalculateBounds();
+            lodGroup.fadeMode = autoLODSettingsData.FadeMode;
+            lodGroup.animateCrossFading = autoLODSettingsData.AnimateCrossFading;
+            lodGroup.ForceLOD(-1);
 
             SyncImporterLODLevels(importerRef, importerLODLevels, lods);
 
@@ -610,6 +618,8 @@ internal static LODData GetLODData(string assetPath)
                 importSettings.initialLODMaxPolyCount = autoLODSettingsData.InitialLODMaxPolyCount;
                 importSettings.hierarchyType = autoLODSettingsData.HierarchyType;
                 importSettings.parentName = autoLODSettingsData.ParentName;
+                importSettings.fadeMode = autoLODSettingsData.FadeMode;
+                importSettings.animateCrossFading = autoLODSettingsData.AnimateCrossFading;
             }
 
             return lodData;

Runtime/AutoLODSettingsData.cs

@@ -32,6 +32,8 @@ public class AutoLODSettingsData : ScriptableObject
         [SerializeField] private bool showVolumeBounds = false;
         [SerializeField] private int maxLOD = AutoLODConst.k_DefaultMaxLOD;
         [SerializeField] private bool useSameMaterialForLODs = false;
+        [SerializeField] private LODFadeMode fadeMode = LODFadeMode.None;
+        [SerializeField] private bool animateCrossFading = false;
 
         [SerializeField] private List<Type> meshSimplifiers;
         [SerializeField] private List<Type> batchers;
@@ -369,6 +371,26 @@ public bool UseSameMaterialForLODs
             }
         }
 
+        public LODFadeMode FadeMode
+        {
+            get => fadeMode;
+            set
+            {
+                fadeMode = value;
+                OnSettingsUpdated?.Invoke();
+            }
+        }
+
+        public bool AnimateCrossFading
+        {
+            get => animateCrossFading;
+            set
+            {
+                animateCrossFading = value;
+                OnSettingsUpdated?.Invoke();
+            }
+        }
+
         public IPreferences SimplifierPreferences
         {
             get => simplifierPreferences;

Runtime/Extensions/LODGroupExtensions.cs

@@ -32,11 +32,17 @@ public static void SetEnabled(this LODGroupHelper lodGroupHelper, bool enabled)
 
         static void SetRenderersEnabled(LOD[] lods, bool enabled)
         {
+            if (lods == null)
+                return;
+
             for (var i = 0; i < lods.Length; i++)
             {
                 var lod = lods[i];
 
                 var renderers = lod.renderers;
+                if (renderers == null)
+                    continue;
+
                 foreach (var r in renderers)
                 {
                     if (r)

Runtime/LODGroupHelper.cs

@@ -66,6 +66,18 @@ public int maxLOD
             }
         }
 
+        /// <summary>
+        /// Invalidates all cached LODGroup data, forcing it to be re-fetched on next access.
+        /// Call this after modifying the LODGroup's LODs, transform, or size externally.
+        /// </summary>
+        public void InvalidateCache()
+        {
+            m_LODs = null;
+            m_ReferencePoint = null;
+            m_WorldSpaceSize = null;
+            m_MaxLOD = null;
+        }
+
         [SerializeField] LODGroup m_LODGroup;
 
         LOD[] m_LODs;

Runtime/LODImportSettings.cs

@@ -1,4 +1,5 @@
 using System;
+using UnityEngine;
 using UnityEngine.Serialization;
 
 namespace Unity.AutoLOD
@@ -13,5 +14,7 @@ public class LODImportSettings
         public int initialLODMaxPolyCount = Int32.MaxValue;
         public LODHierarchyType hierarchyType = LODHierarchyType.ChildOfSource;
         public string parentName = String.Empty;
+        public LODFadeMode fadeMode = LODFadeMode.None;
+        public bool animateCrossFading = false;
     }
 }

Runtime/LODVolume_Editor.cs

@@ -193,6 +193,8 @@ public IEnumerator GenerateHLOD(bool propagateUpwards = true)
 
             lod.renderers = hlodRoot.GetComponentsInChildren<Renderer>(false);
             lodGroup.SetLODs(new LOD[] { lod });
+            lodGroup.fadeMode = AutoLODSettingsData.Instance.FadeMode;
+            lodGroup.animateCrossFading = AutoLODSettingsData.Instance.AnimateCrossFading;
 
             if (propagateUpwards)
             {
@@ -270,6 +272,8 @@ void GenerateLODs()
                 lodGroup.ForceLOD(0);
                 lodGroup.SetLODs(lods.ToArray());
                 lodGroup.RecalculateBounds();
+                lodGroup.fadeMode = AutoLODSettingsData.Instance.FadeMode;
+                lodGroup.animateCrossFading = AutoLODSettingsData.Instance.AnimateCrossFading;
                 lodGroup.ForceLOD(-1);
 
                 var prefab = PrefabUtility.GetCorrespondingObjectFromSource(go);