An additive manufacturing system includes one or more processors configured to determine one or more geometrical characteristics of each of multiple segments of a build part at a candidate position of the build part relative to an additive manufacturing instrument. The one or more geometrical characteristics include an angle of incidence between a beam line extending from an electromagnetic energy source of the additive manufacturing instrument and a surface normal of a respective skin of the corresponding segment proximate to the beam line. The one or more processors are configured to determine, based on one or more geometrical characteristics of the segments at the candidate position, one or more locations of support material to be formed adjacent the build part during a build process of the build part.