[UE4] 將RenderTarget轉成Color陣列以儲存至SaveData

有時我們會需要儲存RenderTarget的Pixel資訊在遊戲存檔，如地圖探索範圍、拍照照片等等。然而UE4的SaveData不支援直接儲存RenderTarget，因此需要轉化成可以儲存的格式。這邊我們使用FColor的陣列儲存。

儲存：RenderTarget至TArray

使用ReadPixels

TArray<FColor> OutputBuffer; UTextureRenderTarget2D* RenderTarget = GetSourceFogRenderTarget(); FTextureRenderTarget2DResource* TextureResource = (FTextureRenderTarget2DResource*)RenderTarget->GameThread_GetRenderTargetResource(); TextureResource->ReadPixels(OutputBuffer);

之後將OutputBuffer以一般陣列儲存即可。

讀取：TArray至RenderTarget

透過Canvas將Pixel資訊畫回RenderTarget\

TArray<FColor> InputBuffer; UTextureRenderTarget2D* RenderTarget = GetSourceFogRenderTarget(); UCanvas* Canvas; FVector2D Size; FDrawToRenderTargetContext RenderContext; UKismetRenderingLibrary::BeginDrawCanvasToRenderTarget(this, RenderTarget, Canvas, Size, RenderContext); if (Canvas) { // 讀取的PixelData寫入Texture (MipMaps [0]) UTexture2D* ReconstructedTexture = UTexture2D::CreateTransient(RenderTarget->SizeX, RenderTarget->SizeY, PF_B8G8R8A8); uint8* MipData = (uint8*)ReconstructedTexture->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE); const int32 DataSize = RenderTarget->SizeY * RenderTarget->SizeX * 4; FMemory::Memcpy(MipData, InputBuffer.GetData(), DataSize); ReconstructedTexture->PlatformData->Mips[0].BulkData.Unlock(); ReconstructedTexture->UpdateResource(); // 將Texture填滿Canvas Canvas->K2_DrawTexture(ReconstructedTexture, FVector2D::ZeroVector, Size, FVector2D(0, 0), FVector2D(1, 1), FLinearColor::White, EBlendMode::BLEND_Opaque); } UKismetRenderingLibrary::EndDrawCanvasToRenderTarget(this, RenderContext);