New: Add interface-filtered object references

Add native hard and soft reference types for scene objects that implement
a scripting interface:

- ScriptingObjectInterfaceReference<T>
- SoftObjectInterfaceReference<T>

Source/Engine/Scripting/Attributes/Editor/ScriptingObjectInterfaceReferenceAttribute.cs

@@ -0,0 +1,14 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+using System;
+
+namespace FlaxEngine
+{
+    /// <summary>
+    /// Marks a generated interface property as a native scripting object interface reference.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property)]
+    public sealed class ScriptingObjectInterfaceReferenceAttribute : Attribute
+    {
+    }
+}

Source/Engine/Scripting/Attributes/Editor/SoftObjectInterfaceReferenceAttribute.cs

@@ -0,0 +1,14 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+using System;
+
+namespace FlaxEngine
+{
+    /// <summary>
+    /// Marks a generated interface property as a native soft object interface reference.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property)]
+    public sealed class SoftObjectInterfaceReferenceAttribute : Attribute
+    {
+    }
+}

Source/Engine/Scripting/Internal/InternalCalls.h

@@ -37,7 +37,7 @@ struct FLAXENGINE_API VTableFunctionInjector
 
 #if USE_NETCORE
 #define ADD_INTERNAL_CALL(fullName, method)
-#define DEFINE_INTERNAL_CALL(returnType) extern "C" DLLEXPORT returnType
+#define DEFINE_INTERNAL_CALL(returnType) extern "C" DLLEXPORT USED returnType
 #else
 extern "C" FLAXENGINE_API void mono_add_internal_call(const char* name, const void* method);
 #define ADD_INTERNAL_CALL(fullName, method) mono_add_internal_call(fullName, (const void*)method)

Source/Engine/Scripting/ManagedCLR/MUtils.h

@@ -278,6 +278,10 @@ struct MConverter<T, typename TEnableIf<TIsBaseOf<class ScriptingObject, T>::Val
 // Converter for ScriptingObject References.
 template<typename T>
 class ScriptingObjectReference;
+template<typename T>
+class ScriptingObjectInterfaceReference;
+template<typename T>
+class SoftObjectInterfaceReference;
 
 template<typename T>
 struct MConverter<ScriptingObjectReference<T>>
@@ -311,6 +315,50 @@ struct MConverter<ScriptingObjectReference<T>>
     }
 };
 
+template<typename TReference, typename TInterface>
+struct MInterfaceReferenceConverter
+{
+    MObject* Box(const TReference& data, const MClass* klass)
+    {
+        return data.GetManagedInstance();
+    }
+
+    void Unbox(TReference& result, MObject* data)
+    {
+        result = ScriptingObject::ToInterface<TInterface>(ScriptingObject::ToNative(data));
+    }
+
+    void ToManagedArray(MArray* result, const Span<TReference>& data)
+    {
+        if (data.Length() == 0)
+            return;
+        MObject** objects = (MObject**)Allocator::Allocate(data.Length() * sizeof(MObject*));
+        for (int32 i = 0; i < data.Length(); i++)
+            objects[i] = data[i].GetManagedInstance();
+        MCore::GC::WriteArrayRef(result, Span<MObject*>(objects, data.Length()));
+        Allocator::Free(objects);
+    }
+
+    void ToNativeArray(Span<TReference>& result, const MArray* data)
+    {
+        MObject** dataPtr = MCore::Array::GetAddress<MObject*>(data);
+        for (int32 i = 0; i < result.Length(); i++)
+            result.Get()[i] = ScriptingObject::ToInterface<TInterface>(ScriptingObject::ToNative(dataPtr[i]));
+    }
+};
+
+// Converter for Scripting Interface References.
+template<typename T>
+struct MConverter<ScriptingObjectInterfaceReference<T>> : MInterfaceReferenceConverter<ScriptingObjectInterfaceReference<T>, T>
+{
+};
+
+// Converter for Soft Object Interface References.
+template<typename T>
+struct MConverter<SoftObjectInterfaceReference<T>> : MInterfaceReferenceConverter<SoftObjectInterfaceReference<T>, T>
+{
+};
+
 // Converter for Asset References.
 template<typename T>
 class AssetReference;

Source/Engine/Scripting/ScriptingObjectInterfaceReference.h

@@ -0,0 +1,195 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Scripting/ScriptingObjectInterfaceReferenceUtils.h"
+
+/// <summary>
+/// The scene object interface reference.
+/// </summary>
+/// <typeparam name="T">The type of the scripting interface.</typeparam>
+template<typename T>
+API_CLASS(InBuild) class ScriptingObjectInterfaceReference : public ScriptingObjectReferenceBase
+{
+    typedef ScriptingObjectInterfaceReferenceHelper<T> Helper;
+
+public:
+    typedef ScriptingObjectInterfaceReference<T> Type;
+
+public:
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    ScriptingObjectInterfaceReference()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="obj">The object to link.</param>
+    ScriptingObjectInterfaceReference(SceneObject* obj)
+        : ScriptingObjectReferenceBase(Helper::IsValidObject(obj) ? obj : nullptr)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="interfaceObj">The interface object to link.</param>
+    ScriptingObjectInterfaceReference(T* interfaceObj)
+        : ScriptingObjectReferenceBase(Helper::GetSceneObject(interfaceObj))
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="other">The other property.</param>
+    ScriptingObjectInterfaceReference(const ScriptingObjectInterfaceReference& other)
+        : ScriptingObjectReferenceBase(other._object)
+    {
+    }
+
+    ScriptingObjectInterfaceReference(ScriptingObjectInterfaceReference&& other) noexcept
+        : ScriptingObjectReferenceBase(MoveTemp(other))
+    {
+    }
+
+    /// <summary>
+    /// Finalizes an instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    ~ScriptingObjectInterfaceReference()
+    {
+    }
+
+public:
+    FORCE_INLINE bool operator==(SceneObject* other) const
+    {
+        return _object == other;
+    }
+
+    FORCE_INLINE bool operator!=(SceneObject* other) const
+    {
+        return _object != other;
+    }
+
+    FORCE_INLINE bool operator==(T* other) const
+    {
+        return Get() == other;
+    }
+
+    FORCE_INLINE bool operator!=(T* other) const
+    {
+        return Get() != other;
+    }
+
+    FORCE_INLINE bool operator==(const ScriptingObjectInterfaceReference& other) const
+    {
+        return _object == other._object;
+    }
+
+    FORCE_INLINE bool operator!=(const ScriptingObjectInterfaceReference& other) const
+    {
+        return _object != other._object;
+    }
+
+    FORCE_INLINE ScriptingObjectInterfaceReference& operator=(SceneObject* other)
+    {
+        OnSet(Helper::IsValidObject(other) ? other : nullptr);
+        return *this;
+    }
+
+    FORCE_INLINE ScriptingObjectInterfaceReference& operator=(T* other)
+    {
+        OnSet(Helper::GetSceneObject(other));
+        return *this;
+    }
+
+    ScriptingObjectInterfaceReference& operator=(const ScriptingObjectInterfaceReference& other)
+    {
+        OnSet(other._object);
+        return *this;
+    }
+
+    ScriptingObjectInterfaceReference& operator=(ScriptingObjectInterfaceReference&& other) noexcept
+    {
+        ScriptingObjectReferenceBase::operator=(MoveTemp(other));
+        return *this;
+    }
+
+    FORCE_INLINE ScriptingObjectInterfaceReference& operator=(const Guid& id)
+    {
+        OnSet(Helper::FindSceneObject(id));
+        return *this;
+    }
+
+    /// <summary>
+    /// Implicit conversion to the interface.
+    /// </summary>
+    FORCE_INLINE operator T*() const
+    {
+        return Get();
+    }
+
+    /// <summary>
+    /// Implicit conversion to boolean value.
+    /// </summary>
+    FORCE_INLINE operator bool() const
+    {
+        return _object != nullptr;
+    }
+
+    /// <summary>
+    /// Interface accessor.
+    /// </summary>
+    FORCE_INLINE T* operator->() const
+    {
+        return Get();
+    }
+
+    /// <summary>
+    /// Gets the interface pointer.
+    /// </summary>
+    FORCE_INLINE T* Get() const
+    {
+        return ScriptingObject::ToInterface<T>(_object);
+    }
+
+    /// <summary>
+    /// Gets the referenced object.
+    /// </summary>
+    FORCE_INLINE SceneObject* GetObject() const
+    {
+        return static_cast<SceneObject*>(_object);
+    }
+
+    /// <summary>
+    /// Copies the object ID into the raw storage.
+    /// </summary>
+    FORCE_INLINE void CopyID(uint32 id[4]) const
+    {
+        memset(id, 0, sizeof(uint32) * 4);
+        if (_object)
+        {
+            const Guid value = GetID();
+            memcpy(id, &value, sizeof(uint32) * 4);
+        }
+    }
+
+    /// <summary>
+    /// Gets the object as a given type (static cast).
+    /// </summary>
+    template<typename U>
+    FORCE_INLINE U* As() const
+    {
+        return static_cast<U*>(_object);
+    }
+
+};
+
+template<typename T>
+uint32 GetHash(const ScriptingObjectInterfaceReference<T>& key)
+{
+    return GetHash(key.GetID());
+}

Source/Engine/Scripting/ScriptingObjectInterfaceReferenceUtils.h

@@ -0,0 +1,30 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Scripting/ScriptingObjectReference.h"
+#include "Engine/Level/SceneObject.h"
+
+/// <summary>
+/// Utility methods for scene object interface references.
+/// </summary>
+/// <typeparam name="T">The type of the scripting interface.</typeparam>
+template<typename T>
+struct ScriptingObjectInterfaceReferenceHelper
+{
+    FORCE_INLINE static bool IsValidObject(const SceneObject* obj)
+    {
+        return !obj || obj->GetType().GetInterface(T::TypeInitializer) != nullptr;
+    }
+
+    FORCE_INLINE static SceneObject* GetSceneObject(T* interfaceObj)
+    {
+        return ScriptingObject::Cast<SceneObject>(ScriptingObject::FromInterface<T>(interfaceObj));
+    }
+
+    FORCE_INLINE static SceneObject* FindSceneObject(const Guid& id)
+    {
+        SceneObject* obj = static_cast<SceneObject*>(FindObject(id, SceneObject::GetStaticClass()));
+        return IsValidObject(obj) ? obj : nullptr;
+    }
+};

Source/Engine/Scripting/SoftObjectInterfaceReference.h

@@ -0,0 +1,258 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Scripting/SoftObjectReference.h"
+#include "Engine/Scripting/ScriptingObjectInterfaceReferenceUtils.h"
+
+/// <summary>
+/// The scene object soft interface reference. Objects gets referenced on use (ID reference is resolving it).
+/// </summary>
+/// <typeparam name="T">The type of the scripting interface.</typeparam>
+template<typename T>
+API_CLASS(InBuild) class SoftObjectInterfaceReference : public SoftObjectReferenceBase
+{
+    typedef ScriptingObjectInterfaceReferenceHelper<T> Helper;
+
+public:
+    typedef SoftObjectInterfaceReference<T> Type;
+
+public:
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SoftObjectInterfaceReference"/> class.
+    /// </summary>
+    SoftObjectInterfaceReference()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SoftObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="obj">The object to link.</param>
+    SoftObjectInterfaceReference(SceneObject* obj)
+    {
+        OnSet(Helper::IsValidObject(obj) ? obj : nullptr);
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SoftObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="interfaceObj">The interface object to link.</param>
+    SoftObjectInterfaceReference(T* interfaceObj)
+    {
+        OnSet(Helper::GetSceneObject(interfaceObj));
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SoftObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="other">The other property.</param>
+    SoftObjectInterfaceReference(const SoftObjectInterfaceReference& other)
+    {
+        OnSet(other.GetID());
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="SoftObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="other">The other property.</param>
+    SoftObjectInterfaceReference(SoftObjectInterfaceReference&& other)
+    {
+        OnSet(other.GetID());
+        other.OnSet(nullptr);
+    }
+
+    /// <summary>
+    /// Finalizes an instance of the <see cref="SoftObjectInterfaceReference"/> class.
+    /// </summary>
+    ~SoftObjectInterfaceReference()
+    {
+    }
+
+public:
+    FORCE_INLINE bool operator==(SceneObject* other)
+    {
+        return GetObject() == other;
+    }
+
+    FORCE_INLINE bool operator!=(SceneObject* other)
+    {
+        return GetObject() != other;
+    }
+
+    FORCE_INLINE bool operator==(T* other)
+    {
+        return Get() == other;
+    }
+
+    FORCE_INLINE bool operator!=(T* other)
+    {
+        return Get() != other;
+    }
+
+    FORCE_INLINE bool operator==(const SoftObjectInterfaceReference& other)
+    {
+        return GetID() == other.GetID();
+    }
+
+    FORCE_INLINE bool operator!=(const SoftObjectInterfaceReference& other)
+    {
+        return GetID() != other.GetID();
+    }
+
+    SoftObjectInterfaceReference& operator=(const SoftObjectInterfaceReference& other)
+    {
+        if (this != &other)
+            OnSet(other.GetID());
+        return *this;
+    }
+
+    SoftObjectInterfaceReference& operator=(SoftObjectInterfaceReference&& other)
+    {
+        if (this != &other)
+        {
+            OnSet(other.GetID());
+            other.OnSet(nullptr);
+        }
+        return *this;
+    }
+
+    FORCE_INLINE SoftObjectInterfaceReference& operator=(SceneObject* other)
+    {
+        OnSet(Helper::IsValidObject(other) ? other : nullptr);
+        return *this;
+    }
+
+    FORCE_INLINE SoftObjectInterfaceReference& operator=(T* other)
+    {
+        OnSet(Helper::GetSceneObject(other));
+        return *this;
+    }
+
+    FORCE_INLINE SoftObjectInterfaceReference& operator=(const Guid& id)
+    {
+        OnSet(id);
+        return *this;
+    }
+
+    /// <summary>
+    /// Implicit conversion to the interface.
+    /// </summary>
+    FORCE_INLINE operator T*() const
+    {
+        return Get();
+    }
+
+    /// <summary>
+    /// Implicit conversion to boolean value.
+    /// </summary>
+    FORCE_INLINE operator bool() const
+    {
+        return Get() != nullptr;
+    }
+
+    /// <summary>
+    /// Interface accessor.
+    /// </summary>
+    FORCE_INLINE T* operator->() const
+    {
+        return Get();
+    }
+
+    /// <summary>
+    /// Gets the object as a given type (static cast).
+    /// </summary>
+    template<typename U>
+    FORCE_INLINE U* As() const
+    {
+        return static_cast<U*>(GetObject());
+    }
+
+public:
+    /// <summary>
+    /// Gets the interface pointer.
+    /// </summary>
+    FORCE_INLINE T* Get() const
+    {
+        return ScriptingObject::ToInterface<T>(GetObject());
+    }
+
+    /// <summary>
+    /// Gets the referenced object.
+    /// </summary>
+    SceneObject* GetObject() const
+    {
+        if (!_object)
+            const_cast<SoftObjectInterfaceReference*>(this)->OnResolve(SceneObject::GetStaticClass());
+        return Helper::IsValidObject(static_cast<SceneObject*>(_object)) ? static_cast<SceneObject*>(_object) : nullptr;
+    }
+
+    /// <summary>
+    /// Gets managed instance object (or null if no object linked).
+    /// </summary>
+    MObject* GetManagedInstance() const
+    {
+        auto object = GetObject();
+        return object ? object->GetOrCreateManagedInstance() : nullptr;
+    }
+
+    /// <summary>
+    /// Determines whether object is assigned and managed instance of the object is alive.
+    /// </summary>
+    bool HasManagedInstance() const
+    {
+        auto object = GetObject();
+        return object && object->HasManagedInstance();
+    }
+
+    /// <summary>
+    /// Gets the managed instance object or creates it if missing or null if not assigned.
+    /// </summary>
+    MObject* GetOrCreateManagedInstance() const
+    {
+        auto object = GetObject();
+        return object ? object->GetOrCreateManagedInstance() : nullptr;
+    }
+
+    /// <summary>
+    /// Copies the object ID into the raw storage.
+    /// </summary>
+    FORCE_INLINE void CopyID(uint32 id[4]) const
+    {
+        const Guid value = GetID();
+        memcpy(id, &value, sizeof(uint32) * 4);
+    }
+
+    /// <summary>
+    /// Sets the object.
+    /// </summary>
+    /// <param name="id">The object ID. Uses Scripting to find the registered object of the given ID.</param>
+    FORCE_INLINE void Set(const Guid& id)
+    {
+        OnSet(id);
+    }
+
+    /// <summary>
+    /// Sets the object.
+    /// </summary>
+    /// <param name="object">The object.</param>
+    FORCE_INLINE void Set(SceneObject* object)
+    {
+        OnSet(Helper::IsValidObject(object) ? object : nullptr);
+    }
+
+    /// <summary>
+    /// Sets the object.
+    /// </summary>
+    /// <param name="interfaceObj">The interface object.</param>
+    FORCE_INLINE void Set(T* interfaceObj)
+    {
+        OnSet(Helper::GetSceneObject(interfaceObj));
+    }
+};
+
+template<typename T>
+uint32 GetHash(const SoftObjectInterfaceReference<T>& key)
+{
+    return GetHash(key.GetID());
+}