Share sampler state objects between textures

#rb none

#ROBOMERGE-OWNER: dmitriy.dyomin
#ROBOMERGE-AUTHOR: dmitriy.dyomin
#ROBOMERGE-SOURCE: CL 11596383 via CL 11596386 via CL 11596387
#ROBOMERGE-BOT: (v656-11643781)

[CL 11722115 by dmitriy dyomin in Main branch]

Engine/Source/Runtime/RenderCore/Private/RenderResource.cpp

@@ -796,3 +796,36 @@ void FMipBiasFade::SetNewMipCount( float ActualMipCount, float TargetMipCount, d
 		}
 	}
 }
+
+class FTextureSamplerStateCache : public FRenderResource
+{
+public:
+	TMap<FSamplerStateInitializerRHI, FRHISamplerState*> Samplers;
+
+	virtual void ReleaseRHI() override
+	{
+		for (auto Pair : Samplers)
+		{
+			Pair.Value->Release();
+		}
+		Samplers.Empty();
+	}
+};
+
+TGlobalResource<FTextureSamplerStateCache> GTextureSamplerStateCache;
+
+FRHISamplerState* FTexture::GetOrCreateSamplerState(const FSamplerStateInitializerRHI& Initializer)
+{
+	FRHISamplerState** Found = GTextureSamplerStateCache.Samplers.Find(Initializer);
+	if (Found)
+	{
+		return *Found;
+	}
+	
+	FSamplerStateRHIRef NewState = RHICreateSamplerState(Initializer);
+	
+	// Add an extra reference so we don't have TRefCountPtr in the maps
+	NewState->AddRef();
+	GTextureSamplerStateCache.Samplers.Add(Initializer, NewState);
+	return NewState;
+}