polygon smoothing on procedural mesh

i have created a procedural mesh of say, a picture frame, and have chamfered the edges at 45 degrees, and created flattened out uv coordinates, and assigned a dynamic material, but it seems the engine applies polygon smoothing over the edges so i can not see the chamfer really.

i know wheni import fbx files there are smoothing groups. can i program these or something similar myself for my procedural mesh so the chamfers are more visible? where do i look?