Faces

Faces exist in planar topology only and represent the interior of an area formed by enclosing edges. A polygon is represented by one or more faces.

The edges describe the outer and inner boundaries of the face geometry and any edges contained by, but not bounding, the face.

To ensure that faces never overlap, 1Integrate will automatically insert a node and split into multiple edges wherever lines or polygon boundaries cross or meet. The features are not spit, but the underlying topology will be represented using multiple edges.

Adjacent faces share an edge, which means that the automatically maintained face-to-edge relationship can be used to very rapidly calculate geometric adjacency using Reference conditions.

Example: In the example diagram below, f0 is a universe face (sys:is_universe_face) that surrounds all other faces. When creating Rules and Actions the universe face is often ignored.

Two overlapping hexagons with faces and nodes labled (n1, n2, f1, f2 etc) — Example faces

A face class has the following references:

Reference	Description
`sys:face_to_edge`	A `sys:face` and a `sys:edge` are related by the reference if an edge represents a boundary of the face.
`sys:face_to_node`	A `sys:face` and `sys:node` are related by this reference if the node is isolated and contained by the face.
`sys:area_to_face`	Faces can also use `sys:area_to_face` reference on any polygon features that use the face.