[cubefox]

The mesh shader pipeline isn't just an addition, it replaces several pieces of the old pipeline, like vertex shader, tesselation and geometry shaders. It's a pretty big departure. Though most engines don't use it yet I believe.

[hnuser123456]

Does switching a UE5 game to lumen/nanite switch from essentially the "old pipeline" to the new mesh shader path, or do even the non-lumen/nanite modes use the mesh shaders?

[cubefox]

Maybe optionally if the hardware supports it, but new UE5 features also work with older cards that already support compute shaders (a specialized pipeline which was introduced somewhat earlier) but no mesh shaders.