Module offset 

Polygon offset via raw edge offset with miter/bevel joins.

Offsets a simple polygon by moving each edge along its outward normal, then computing miter (or bevel) joins at vertices. Self-intersections in the raw offset are detected and resolved by splitting into sub-loops and filtering by signed area.

Algorithm

1. Ensure CCW winding
2. Offset each edge by translating along its outward normal
3. Compute miter joins at consecutive offset edges
4. Apply miter limit – bevel if ratio exceeds threshold
5. Detect and resolve self-intersections

Complexity

O(n^2) worst case for self-intersection resolution on concave polygons, O(n) for convex polygons.

References

• Held (1998), “On the Computational Geometry of Pocket Machining”, Ch. 3
• Chen & McMains (2005), “Polygon Offsetting by Computing Winding Numbers”

Functions

line_intersection

Computes the intersection of two lines defined by point + direction.

offset_edge

Offsets a single directed edge segment by translating along its outward normal.

offset_polygon

Offsets a simple polygon by distance using the default miter limit (2.0).

offset_polygon_miter

Offsets a simple polygon by distance with a configurable miter limit.