Fix prefab preview to wait for the assets streaming

Source/Editor/Content/Proxy/PrefabProxy.cs

@@ -122,9 +122,7 @@ namespace FlaxEditor.Content
                 return false;
 
             // Check if asset is streamed enough
-            var asset = (Prefab)request.Asset;
-            // TODO: check all prefab actors to have loaded resources (models/textures/etc.)
-            return asset.IsLoaded;
+            return ThumbnailsModule.HasMinimumQuality((Prefab)request.Asset);
         }
 
         private void Prepare(Actor actor, ref BoundingBox bounds)

Source/Editor/Content/Thumbnails/ThumbnailsModule.cs

@@ -181,6 +181,14 @@ namespace FlaxEditor.Content.Thumbnails
             return baseMaterial == null || HasMinimumQualityInternal(baseMaterial);
         }
 
+        internal static bool HasMinimumQuality(Prefab asset)
+        {
+            if (!asset.IsLoaded)
+                return false;
+            var defaultInstance = asset.GetDefaultInstance();
+            return defaultInstance == null || HasMinimumQualityInternal(defaultInstance);
+        }
+
         private static bool HasMinimumQualityInternal(MaterialBase asset)
         {
             if (!asset.IsLoaded)
@@ -194,6 +202,43 @@ namespace FlaxEditor.Content.Thumbnails
             return true;
         }
 
+        private static bool HasMinimumQualityInternal(Actor actor)
+        {
+            if (!actor.IsActive)
+                return true;
+
+            if (actor is ModelInstanceActor modelInstance)
+            {
+                var model = modelInstance.GetModel();
+                if (model && !HasMinimumQuality(model))
+                    return false;
+                var slots = modelInstance.MaterialSlots;
+                foreach (var slot in slots)
+                {
+                    if (slot.Material && !HasMinimumQuality(slot.Material))
+                        return false;
+                }
+            }
+            if (actor is SpriteRender spriteRender)
+            {
+                if (spriteRender.Material && !HasMinimumQuality(spriteRender.Material))
+                    return false;
+            }
+            if (actor is TextRender textRender)
+            {
+                if (textRender.Material && !HasMinimumQuality(textRender.Material))
+                    return false;
+            }
+
+            for (int i = 0; i < actor.ChildrenCount; i++)
+            {
+                if (!HasMinimumQualityInternal(actor.GetChild(i)))
+                    return false;
+            }
+
+            return true;
+        }
+
         #region IContentItemOwner
 
         /// <inheritdoc />

Source/Engine/Level/Actors/AnimatedModel.cpp

@@ -1332,6 +1332,11 @@ MaterialBase* AnimatedModel::GetMaterial(int32 entryIndex)
     return material;
 }
 
+ModelBase* AnimatedModel::GetModel()
+{
+    return SkinnedModel.Get();
+}
+
 bool AnimatedModel::IntersectsEntry(int32 entryIndex, const Ray& ray, Real& distance, Vector3& normal)
 {
     auto model = SkinnedModel.Get();

Source/Engine/Level/Actors/AnimatedModel.h

@@ -476,6 +476,7 @@ public:
     void Deserialize(DeserializeStream& stream, ISerializeModifier* modifier) override;
     const Span<MaterialSlot> GetMaterialSlots() const override;
     MaterialBase* GetMaterial(int32 entryIndex) override;
+    ModelBase* GetModel() override;
     bool IntersectsEntry(int32 entryIndex, const Ray& ray, Real& distance, Vector3& normal) override;
     bool IntersectsEntry(const Ray& ray, Real& distance, Vector3& normal, int32& entryIndex) override;
     bool GetMeshData(const MeshReference& ref, MeshBufferType type, BytesContainer& result, int32& count, GPUVertexLayout** layout) const override;

Source/Engine/Level/Actors/ModelInstanceActor.h

@@ -66,6 +66,11 @@ public:
     /// <param name="entryIndex">The material slot entry index.</param>
     API_FUNCTION(Sealed) virtual MaterialBase* GetMaterial(int32 entryIndex) = 0;
 
+    /// <summary>
+    /// Gets the model (base class).
+    /// </summary>
+    API_FUNCTION(Sealed) virtual ModelBase* GetModel() = 0;
+
     /// <summary>
     /// Sets the material to the entry slot. Can be used to override the material of the meshes using this slot.
     /// </summary>

Source/Engine/Level/Actors/SplineModel.cpp

@@ -367,6 +367,11 @@ MaterialBase* SplineModel::GetMaterial(int32 entryIndex)
     return material;
 }
 
+ModelBase* SplineModel::GetModel()
+{
+    return Model.Get();
+}
+
 void SplineModel::UpdateBounds()
 {
     OnSplineUpdated();

Source/Engine/Level/Actors/SplineModel.h

@@ -117,6 +117,7 @@ public:
     void OnParentChanged() override;
     const Span<MaterialSlot> GetMaterialSlots() const override;
     MaterialBase* GetMaterial(int32 entryIndex) override;
+    ModelBase* GetModel() override;
     void UpdateBounds() override;
 
 protected:

Source/Engine/Level/Actors/StaticModel.cpp

@@ -599,6 +599,11 @@ MaterialBase* StaticModel::GetMaterial(int32 entryIndex)
     return material;
 }
 
+ModelBase* StaticModel::GetModel()
+{
+    return Model.Get();
+}
+
 bool StaticModel::IntersectsEntry(int32 entryIndex, const Ray& ray, Real& distance, Vector3& normal)
 {
     auto model = Model.Get();

Source/Engine/Level/Actors/StaticModel.h

@@ -178,6 +178,7 @@ public:
     void Deserialize(DeserializeStream& stream, ISerializeModifier* modifier) override;
     const Span<MaterialSlot> GetMaterialSlots() const override;
     MaterialBase* GetMaterial(int32 entryIndex) override;
+    ModelBase* GetModel() override;
     bool IntersectsEntry(int32 entryIndex, const Ray& ray, Real& distance, Vector3& normal) override;
     bool IntersectsEntry(const Ray& ray, Real& distance, Vector3& normal, int32& entryIndex) override;
     bool GetMeshData(const MeshReference& ref, MeshBufferType type, BytesContainer& result, int32& count, GPUVertexLayout** layout) const override;