Shadowing surfaces

To reduce the calculation time for shadowing calculations, the thermal solver creates internal shadowing surfaces by combining adjacent elements that lie in the same plane and point in the same direction. Shadowing surfaces form n-sided polygons that do not have holes.

Warped quadrilateral elements are split into two separate triangular shadowing surfaces. Lump mass and beam elements also become separate shadowing surfaces.

Elements flagged as non-shadowing are not included in shadowing surfaces.