Dynamic shadows artifacts

[IronicParadox]

Like I posted earlier in the thread:

@IronicParadox

*There is a whole section about screen space PCF ddx/ddy filtering. It also states that it’s a pretty complex operation, meaning it has a non-trivial performance cost. *Keep in mind that you can quickly google to find more versions and variations of these types of filtering

Cascaded Shadow Maps - Win32 apps | Microsoft Learn

The problem lies in properly fitting it into the UE rendering path and doing it in a way that minimizes impact on frame time. There is a lot asynchronicity in the rendering engine and I’m pretty sure that plays a lot into the mix as to why they haven’t implemented it already. In that article, it even states “Because this technique is computationally complex, it should be used only when a GPU has compute cycles to spare.” The problem is that the UE rendering engine is already pretty optimized in filling up empty cycles.

You’d have a few options to pick from:
1)Let it lock up GPU to calculate completely and immediately
2)Mess around with priorities and “spare cycles,” so that this filtering would have a higher priority and finish sooner
3)Let it constantly update over several frames like DFAO

#3 would be the best trade off between performance vs quality. It would be made to have an iterative approach where it’s filter quality starts out course and progresses into finer and finer accuracy. So it might start out looking a tiny bit like the faceting problem and over a couple frames, it would smooth out to look closer to what the soft shadow filtering looks like.