Fix scene lightmaps removal clearing actors linkage to lightmaps

Source/Engine/Foliage/Foliage.cpp

@@ -993,6 +993,12 @@ void Foliage::RemoveAllInstances()
     RebuildClusters();
 }
 
+void Foliage::RemoveLightmap()
+{
+    for (auto& e : Instances)
+        e.RemoveLightmap();
+}
+
 static float GlobalDensityScale = 1.0f;
 
 float Foliage::GetGlobalDensityScale()

Source/Engine/Foliage/Foliage.h

@@ -139,6 +139,11 @@ public:
     /// </summary>
     API_FUNCTION() void RemoveAllInstances();
 
+    /// <summary>
+    /// Removes the lightmap data from the foliage instances.
+    /// </summary>
+    API_FUNCTION() void RemoveLightmap();
+
 public:
     /// <summary>
     /// Gets the global density scale for all foliage instances. The default value is 1. Use values from range 0-1. Lower values decrease amount of foliage instances in-game. Use it to tweak game performance for slower devices.

Source/Engine/Level/Scene/Scene.cpp

@@ -7,6 +7,7 @@
 #include "Engine/Content/Content.h"
 #include "Engine/Content/Deprecated.h"
 #include "Engine/Content/Factories/JsonAssetFactory.h"
+#include "Engine/Foliage/Foliage.h"
 #include "Engine/Physics/Colliders/MeshCollider.h"
 #include "Engine/Level/Actors/StaticModel.h"
 #include "Engine/Level/ActorsCache.h"
@@ -15,6 +16,7 @@
 #include "Engine/Navigation/NavMesh.h"
 #include "Engine/Profiler/ProfilerCPU.h"
 #include "Engine/Serialization/Serialization.h"
+#include "Engine/Terrain/Terrain.h"
 #if USE_EDITOR
 #include "Engine/Engine/Globals.h"
 #endif
@@ -98,6 +100,19 @@ void Scene::SetLightmapSettings(const LightmapSettings& value)
 void Scene::ClearLightmaps()
 {
     LightmapsData.ClearLightmaps();
+
+    // Unlink any actors from lightmap
+    Function<bool(Actor*)> function = [this](Actor* actor)
+    {
+        if (auto* staticModel = Cast<StaticModel>(actor))
+            staticModel->RemoveLightmap();
+        else if (auto* terrain = Cast<Terrain>(actor))
+            terrain->RemoveLightmap();
+        else if (auto* foliage = Cast<Foliage>(actor))
+            foliage->RemoveLightmap();
+        return true;
+    };
+    TreeExecute(function);
 }
 
 void Scene::BuildCSG(float timeoutMs)