If you calculate the angle of impact for the impacted polygon and adjust the angle based on shell caliber Vs the armor thickness
We do this in every game since 2004. This is elementary.
In GTMF also considered a contact place of projectile head shape (not a material point) with the barrier/armor.
The only way to calculate a game more accurately is if every polygon contains density data.
This is also done for each texel, using the armor map. Here, too, there is nothing difficult.
