Module edge 

Low-level segment and edge geometry primitives.

Used by ST_Contains, ST_Intersects, and ST_Distance. All operations are planar (coordinate-space), not spherical. This is correct for the small-area geometries typical of spatial predicates (city blocks, not hemispheres). For large-area work, haversine handles the globe.

Enums

Orientation

Orientation of three points (collinear, clockwise, counter-clockwise). Uses the cross product of vectors (p→q) and (p→r).

Functions

on_segment

Whether point q lies on segment p-r (given that p, q, r are collinear).

orientation

Compute orientation of ordered triplet (p, q, r).

point_on_ring_boundary

Whether a point lies on any edge of a polygon ring.

point_on_segment

Whether a point lies exactly on a line segment (within epsilon tolerance).

point_to_segment_dist_sq

Minimum squared distance from a point to a line segment.

ring_edges

Extract all edges from a polygon ring as segment pairs.

segment_to_segment_dist_sq

Minimum squared distance between two line segments.

segments_intersect

Whether two segments (p1-q1) and (p2-q2) intersect.