Subpath

Subpath (from scenerystack/kite) holds one connected, ordered run of Segments — the layer between individual segments and a whole Shape. Every Shape is really just an array of these: shape.subpaths is a Subpath[], and each call to moveTo() on a Shape starts a new one. A single moveTo().lineTo().lineTo() traces one Subpath; calling moveTo() again (or drawing a shape with multiple disconnected pieces, like the two loops of a letter "B") starts another.

import { Shape } from 'scenerystack/kite';

const shape = new Shape()
  .moveTo( 0, 0 ).lineTo( 100, 0 ).lineTo( 50, 80 ).close()   // subpath 0: a triangle
  .moveTo( 200, 0 ).lineTo( 300, 0 );                          // subpath 1: an open line

shape.subpaths.length;          // 2
shape.subpaths[ 0 ].closed;     // true  - closed with .close()
shape.subpaths[ 0 ].segments;   // the 3 Line segments making up the triangle
shape.subpaths[ 1 ].closed;     // false - never closed

A Subpath being closed isn't the same as its first and last points coinciding

closed reflects whether .close() was called (which also appends a real closing segment connecting the last point back to the first, via getClosingSegment()) — it's not inferred from geometry. A subpath whose last lineTo() happens to land exactly on the start point, but which never called .close(), still reports closed === false and has no closing segment. Use isClosed() (equivalent to reading .closed) rather than comparing getFirstPoint()/getLastPoint() yourself.

Constructor

new Subpath( segments?: Segment[], points?: Vector2[], closed?: boolean )

You'll rarely construct a Subpath directly — build shapes through Shape's fluent API (moveTo/lineTo/arc/...) and read the resulting shape.subpaths instead. The constructor mainly exists for Shape's own internals (copy(), transform methods) and for advanced code assembling a Shape from pre-built segments.

Public API

Member	Description
segments	The ordered Segment[] making up this subpath
points	The Vector2[] of segment start points, plus the final segment's end point
closed	Whether .close() was called on this subpath
bounds	The Bounds2 union of every segment's bounds
getFirstPoint() / getLastPoint()	The subpath's first and last points
getFirstSegment() / getLastSegment()	The subpath's first and last segments
isClosed()	Same as reading .closed
hasClosingSegment() / getClosingSegment()	A purely geometric check — whether (and what) synthetic Line segment would connect the last point back to the first. This is independent of the closed flag: it returns true whenever the first and last points differ by more than a tiny epsilon, even on a subpath that never called .close()
isDrawable()	Whether there's at least one segment to draw
getArcLength()	Sum of every contained segment's arc length
getFillSegments()	Segments to use for filling — includes the closing segment even if .close() was never explicitly called, since fills always implicitly close
stroked( lineStyles )	Returns Subpath[] describing the outline this subpath would have when stroked with the given LineStyles — what Shape.getStrokedShape() delegates to per subpath
transformed( matrix )	A new Subpath with every segment transformed by a Matrix3
copy()	A shallow-ish copy (new Subpath, same segment/point arrays sliced)

Related

• Shape — the subpaths: Subpath[] container, and the fluent builder that creates them.
• LineStyles — the stroke configuration subpath.stroked() consumes.
• Line — the segment type used for a subpath's synthetic closing segment.