Modifying the postprocessing pipeline through a plugin

Development Rendering
, , , , , ,
1

Hi everyone,

I was wondering if there currently is a roadmap for making the postprocessing pipeline available for modification using the C++ plugin system. In this way there would be possibilities to make new effects and use compute shaders in the postprocessing pipeline and distribute them to users without having them generate a custom UE4 build. As a proof of concept I exposed all of the post processing classes and effects in the renderer module and wrote an override of the FPostProcessing::Process function, the proof of concept worked but is almost certainly going to clash with any of the code changes that would touch the postprocessing codebase. I think that the current implementation of the postprocessing passes using the composition graph works really well and would lend itself to custom pass injection and the removal of passes by a plugin system.

Thanks for looking into this and I look forward to a reply!

Thanks and have a great day,

Juul

2

Not out of the box, no. The problem with the current approach is that many post process effects rely on outputs from other effects, ie, they are order-dependent. So is the deferred renderer, which processes the post processing effects at a set stage. It is almost impossible to have non-data driven approach that would somehow sort the post processing effects and pipe them properly. Imagine that I have an effect that goes after DOF, and you have an effect that goes after DOF, who goes first? There is a substantial amount of work required to have correctly sorted and piped pipeline.

TLDR: No, you cannot do a PP effect from module without modifying the engine, but you are on the right track. You can modify the PostProcessing class or the deferred renderer to fit your need.

3

Does your answer still hold true for UE 4.21?