Recursively replace every edge of a shape's boundary with a bump, the classic Koch curve construction.
Split divides the perimeter into this many equal units before the pattern is applied -- required for a circle (default 24); for a polygon, leave it blank to use the polygon's own sides as-is (e.g. leave it blank with 3 sides for a classic Koch snowflake).
Each iteration replaces every edge with a bump, so point count grows fast -- roughly (bump polygon + 1)× per iteration. Bump polygon 3 (the default) is a triangle, i.e. the classic construction; higher numbers use more sides of a bigger regular polygon for a wider, flatter bump.