do explicit vertex normals cost anything?

AtticusMars

Simple maybe dumb question
Is there any performance cost to using explicit vertex normals?

Eric Chadwick

No.

But if you split a vertex into multiple normals, for example to make a hard edge, that can increase the vertex count of the model, which can cost more memory, which may slow down frame rate. It all depends!

http://wiki.polycount.com/PolygonCount
and
You're making me hard. Making sense of hard edges, uvs, normal maps and vertex counts

AtticusMars

Understood

Thank you for the answer!