FPS drop when Ray Tracing shadows disabled

Development Rendering
1

Hi all,

Yes, it may sound strange, but in a project with Ray Tracing enabled and with a directiona light, if I force to disable ray traced shadows with “r.RayTracing.Shadows 0” (so it changes to “raster” shadows), the performance is less than leaving them enabled. You too?

Thanks!

2

There are cases where raytraced shadows can be cheaper than cascaded shadow maps. It’s generally when you have a very far CSM draw distance and/or high triangle counts in the shadow mesh(or in the case for default Unreal, the rendermesh).

3

Yeah it could make sense. Search for one of the Epic official RTX livestreaming (on the Unreal Engine youtube channel), and you will find some interesting explanation for this.