Specular Color

[Daerst]

I’m interested, how to actually set a specular color in UE4, despite it being physically unplausible?

@Real Shading in Unreal Engine 4. Brian Karis

Fortnite has a non-photorealistic art direction and purposefully uses complementary colors for diffuse and specular reflectance, something that is not physically plausible and intentionally cannot be represented in our new material model. After long discussions, we decided to continue to support the old DiffuseColor/SpecularColor as an engine switch in order to maintain quality in Fortnite, since it was far into development.

How to use that ‘engine switch’? Do I have to recompile the engine, or can I just activate it somewhere?