How can I copy Render target to UTexture2D ?

Development Programming & Scripting C++
1

Hi,
Everything is in the title, how can I copy data from UTextureRendertarget to UTexture2D.
I tried this code :


UTexture2D* texsample = RenderTarget->ConstructTexture2D(this, "TextureSample", EObjectFlags::RF_NoFlags, CTF_DeferCompression);

But pixels from texsample are all black.

3

Do you need to create a UTexture2D at runtime?

Because if you need it at runtime, that’s not the way to go. Instead read the pixels from the RenderTarget using the GameThread_GetRenderTargetResource and ReadPixels functions. Once you have a TArray<FColor> you can create a UTexture2DDynamic which is the correct way to create textures at runtime.

4

Sorry, for reviving an old thread, but I’ve been seeing this same explanation all day, but they all leave one important bit out: how to actually copy the pixels to the UTexture2D/UTexture2DDynamic. The constructors for them do not take a TArray<FColor>. Nor do any of their member functions. Below is the function I’m trying to implement, but I don’t know what to fill in in place of the comment.

UTexture2D* ACameraLens::CapturePhoto()
{
    if (SceneCaptureComponent == nullptr || SceneCaptureComponent->TextureTarget == nullptr) {return nullptr;}
    SceneCaptureComponent->CaptureScene();

    FName TextureName = *FDateTime::Now().ToString();
    UTexture2D* Photo = UTexture2D::CreateTransient(
        SceneCaptureComponent->TextureTarget->SizeX,
        SceneCaptureComponent->TextureTarget->SizeY,
        SceneCaptureComponent->TextureTarget->GetFormat(),
        TextureName);

    TArray<FColor> Pixels;
    SceneCaptureComponent->TextureTarget->GetRenderTargetResource()->ReadPixels(Pixels);
    
    // Now what??

    return Photo;
}
5

Hi BadScientist89,

You don’t need to copy it manually, check out “UpdateTexture2D”:

6

Unfortunately, that does not seem to work for me. Perhaps because the RenderTarget is not square. It’s the same as the screen resolution. The Photo texture remains a blank white texture.

EDIT: It doesn’t work with the screen resolution set to 1080x1080 either, so I’m not sure what the issue is.

7

here’s an extract from some live code of mine:

renderTarget->UpdateTexture2D(texture2d,TSF_RGBA16F,CTF_Compress|CTF_AllowMips|CTF_SRGB,nullptr);

If you do need to copy the pixel data, you can write to it like (just replace the Memset with a Memcopy of the rendertarget pixels):

uint8* TextureData=tex->Source.LockMip(0);
FMemory::Memset(TextureData,clearCol,res*res*tex->Source.GetBytesPerPixel());
tex->Source.UnlockMip(0);
8

Thanks, RecourseDesign!

But for now, I’ve just decided to create a new TextureRenderTarget2D for each image capture and then display them to the player with a dynamic material instance on the image widget. I’m not sure what the difference in overhead is between Texture2D and TextureRenderTarget2D, but if I ever end up needing to convert again, I’ll keep your solution in mind!

[video-to-gif output image]

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