Polyhedron Loop Element (POLOOP)

Primitive Element

Description

The POLOOP represents a planar profile which defines all or part of the shape of a Polyhedron Face (POLFAC). It is defined by a set of edges linking adjacent Point (POIN) elements, the latter being identified by references held in a Loop Points element (LOOPTS) owned by the POLOOP.

The order of the vertices (that is whether they are sequenced clockwise or anticlockwise) is significant. The order for a loop representing a positive polyhedron face is the opposite to that representing a negative polyhedron face. The LMIRR attribute determines whether the face points are read from start to end of the list, or in reverse. Reversing the order changes the loop from a positive outer boundary to a negative hole boundary, or vice versa. By default, points listed anticlockwise correspond to a positive boundary.

Attributes

Legal Owners

Polyhedron Face Element (POLFACE)

Legal Members

Loop Points Element (LOOPTS)

The directions clockwise and anticlockwise refer to the sense when looking from outside of the face into the polyhedron.