Read data from GPU to CPU

[anonymous_user_d9f4baab]

Hi, I’m trying to read data from the GPU to the CPU, sometimes when resize the viewport or start up a new Modal window, I start getting garbage from the GPU, here is the code:

                if (StatsReadback->FrameStatsBuffer.IsValid())
                {
                    FRHICommandListImmediate& RHICmdList = FRHICommandListExecutor::GetImmediateCommandList();
                    //RHICmdList.ImmediateFlush(EImmediateFlushType::FlushRHITwhreadFlushResources);
                    dovi::FrameStats prev = StatsReadback->Stats;
                    void* SrcPtr = RHICmdList.LockStructuredBuffer(StatsReadback->FrameStatsBuffer->StructuredBuffer, 0, StatsReadback->FrameStatsBuffer->StructuredBuffer->GetSize(), RLM_ReadOnly);
                    FMemory::Memcpy(&StatsReadback->Stats, SrcPtr, StatsReadback->FrameStatsBuffer->StructuredBuffer->GetSize());
                    RHICmdList.UnlockStructuredBuffer(StatsReadback->FrameStatsBuffer->StructuredBuffer);


                    if (isnan(StatsReadback->Stats.source_min) || isnan(StatsReadback->Stats.source_mid) || isnan(StatsReadback->Stats.source_max))
                    {
                        //todo: when resizing the window rapidly we may get nans, should we flush?? 
                        StatsReadback->Stats = prev;
                    }

                    StatsReadback->FrameStatsBuffer = nullptr;

                }

                GraphBuilder.QueueBufferExtraction(FrameStats, &StatsReadback->FrameStatsBuffer, FRDGResourceState::EAccess::Read, FRDGResourceState::EPipeline::Compute);

What could be wrong with this code?