UDK comes pre-packed with material functions for various blending modes including overlay. In the mat editor, in the Material Function Library panel (should be on the right under the Material Expressions panel by default), drag in the Blend_Overlay node.
Hi all! I am trying to mimic the overlay function in 3D Max in the UDK material editor. Any tips on what node I should use? Use: Trying to add a grunge map to overlay a base material. * it needs to act like overlay function: add and multiply haven't produced the correct effect.