Cube soften/harden
 

Hey Guys!

Yesterday i was building a WindshieldViper when i faced a thing. Can someone explain me why is it or what is it?
i picked a cube, insert edge loop on it than delete half. I used append poly face than i saw its darker shade than normal.

i used harden edges on it & it became normal (on the rendered picture too).
But why is that dark thing?

check the normals going to Display>Polygons>Face Normals

You can also use the Fill Hole feature instead of the append to polygon. The Fill Hole feature doesn't usually mess with the normals.

Mesh>Fill Hole

What this likely is, is softened normals for the edges. You can select the originally border edges and go Normals > Harden Edge. That should straighten it out.
(oops, didn't read that you already did that)

Maya has to guess whether an edge represents a corner, and the faces should have a hard edge between, or whether this is a smooth surface and it will try to adjust/interpolate the normals to simulate a smoother surface, which is what is happening here it looks like. It's just an artifact of Maya trying to smooth the normals out.

understanding how normals works will tell you what you need to do, stwert said why, although it's not an artifact, it's correct for it to look like that, basically normals on all points of the face will face the same direction, but when you have a 'soft' edge the normals aren't all facing the same way, they point in other directions to make the edge look smooth. normals determine how the light bounces off the surface and affects how dark(?) it is at that point

but to resolve it without hardening the edges you'd have to insert more edges