Is Nanite without Virtual shadows only a Myth?

Trastrastras
Thu, 10 Nov 2022 19:48:49 +0000
Rendering

I have a question about Nanites and not using Virtual shadows map. It is about whether it is possible to use Nanite without Virtual shadow maps so that using a highpoly mesh is as efficient as using a lowpoly mesh without Nanite. If i use Nanite with classic dynamic lights, i get a warning:

“Actor uses Nanite but Virtual Shadow Maps are not enabled in the project settings. Nanite geometry does not support stationary light shadows, and may yield poor visual quality and reduced performance. Nanite geometry works best with virtual shadow maps enabled”

And in documentation to UE5 shadowing is:

Shadow Mapping

The default shadowing method that renders geometry into shadow depth maps. This shadowing method works for all platforms that support dynamic shadowing, but it requires manual setup of shadowing distances and only culls per-component, causing poor performance with high polygon scenes. Also, it does not support Nanite geometry.

I do not use stationary lights. But as far as I understand, classic dynamic lights use Nanite mesh and not fallback mesh and Per Object Shadows? From this I assume that using Nanite with highpoly mesh without Virtual shadow maps is much more expensive than using lowpoly mesh without Nanite? Is it right?

So i have Questions:
If I use Nanite with a mesh that has 50 thousand polygons and with the same mesh that has 500 thousand polygons with lights that are movable and i dont use Distance field shadows or Virtual Shadows. Will there be a big drop in performance?

Is there a way to force Unreal to make the dynamic lights cast shadows from the fallback mesh? Would it save performance if its possible, or is that already solved with Nanite? How? Can somebody explain to me? Pleeeease, help

3 posts - 2 participants