Add RenderBuffers::LinkedCustomBuffers to reuse main game viewport rendered state (eg. GI) in sub-rendered view

Source/Engine/Graphics/RenderBuffers.cpp

@@ -128,6 +128,8 @@ void RenderBuffers::SetUseAlpha(bool value)
 
 const RenderBuffers::CustomBuffer* RenderBuffers::FindCustomBuffer(const StringView& name) const
 {
+    if (LinkedCustomBuffers)
+        return LinkedCustomBuffers->FindCustomBuffer(name);
     for (const CustomBuffer* e : CustomBuffers)
     {
         if (e->Name == name)
@@ -196,6 +198,7 @@ bool RenderBuffers::Init(int32 width, int32 height)
 void RenderBuffers::Release()
 {
     LastEyeAdaptationTime = 0;
+    LinkedCustomBuffers = nullptr;
 
     for (int32 i = 0; i < _resources.Count(); i++)
         _resources[i]->ReleaseGPU();

Source/Engine/Graphics/RenderBuffers.h

@@ -178,6 +178,8 @@ public:
     template<class T>
     T* GetCustomBuffer(const StringView& name)
     {
+        if (LinkedCustomBuffers)
+            return LinkedCustomBuffers->GetCustomBuffer<T>(name);
         CustomBuffer* result = (CustomBuffer*)FindCustomBuffer(name);
         if (!result)
         {
@@ -206,6 +208,11 @@ public:
     /// </remarks>
     API_FIELD(ReadOnly) GPUTexture* MotionVectors;
 
+    /// <summary>
+    /// External Render Buffers used to redirect FindCustomBuffer/GetCustomBuffer calls. Can be linked to other rendering task (eg. main game viewport) to reuse graphics effect state from it (eg. use GI from main game view in in-game camera renderer).
+    /// </summary>
+    API_FIELD() RenderBuffers* LinkedCustomBuffers = nullptr;
+
 public:
     /// <summary>
     /// Allocates the buffers.