Module rings 

Practical SSSR and ring-interior normals for depiction.

Layout backends own coordinates. This module only supplies drawing helpers: which bonds sit in small rings, and unit normals toward the ring centroid so Kekulé offsets stay short and inside (not the acyclic extend-onto-singles path). Mirrors python/xpict/draw/rings.py.

Structs

Ring

One SSSR ring as an ordered atom cycle (atom indices).

Functions

apply_ring_interiors

Fill [BondIn::interior] for ring bonds from SSSR normals.

bond_interior_normals

Unit normals for ring bonds pointing toward the owning (smallest) ring centroid.

find_sssr

Practical SSSR for depiction: unique shortest cycles through each bond.