Custom Post Process Downsampling

Development Rendering
1

Hello!

Is there any method in Material Editor to use at least half-res downsampling on a custom post process materials? Some post process materials such as blur or lens distortion may be really heavy because of computing every pixel on screen which is a waste.
Didn’t found a single material node about that, but I found some shaders in Engine directories such as:


UE_4.24\Engine\Shaders\Private\PostProcessDownsample.usf
UE_4.24\Engine\Shaders\Private\PostProcessMitchellNetravali.usf

Both of them claim to be “PostProcessing down sample”. But is there any practical method of using it? I should clarify that I’m not exactly good in HLSL just at the moment.
Thanks in advance!

2

Nope, there isn’t.

3

That’s too bad :frowning: And also a bit strange. So many Post Process FX assets on Marketplace and no way to downsample any of it? Some of them are ridiculously expensive on a 4K resolutions…

4

You would need at least a plugin and moving post process material into a global shader to perform that pass at different resolution currently.
I, however, do agree, that lack of such functionality in stock is limiting.

5

I know this is a bit of a necropost, but I think the new user scene texture feature will accomplish this. Essentially you can save the scene texture to a temporary render target which supports downscaling and use it as an input for further post processing. The linked tutorial above shows a post process that is blending between a half and quarter res input before applying a multi pass blur, which should serve as good practice for the workflow.