A path is a series of points, connected by very thin (invisible) line segments. Paths can be created as a line from an array of points, or by calling various functions to create or extend another path.

const { line } = require('@jscad/modeling').primitives
const { path2 } = require('@jscad/modeling').geometries
 
const mypathA = line([[10, 10], [-10, 10]])
const mypathB = line([[-10, -10], [10, -10]])
let mypath = path2.concat(mypathA, mypathB)
mypath = path2.close(mypath)

In addition, a path can be open or closed. An open path is typically used to create another by appending additional points. A closed path is final, and has a line segment between first and last points.

The 'path2' geometry is accessed through the modeling API using the following:

const { path2 } = require('@jscad/modeling').geometries

Curved paths can also be simulated. Paths can be created as an 'arc'. (See Appending Points below for more options.)

The 'arc' primitive creates a curved path about a center. The arc is created from line segments placed the same distance from the center, at the given radius. Start and end angles for the arc can also be supplied. The segments specify the number of segments to create per full rotation.

Defaults:

• center : [0, 0]
• radius : 1
• startAngle : 0
• endAngle : PI * 2
• segments : 32

const { arc } = require('@jscad/modeling').primitives
 
const mypath = arc({radius: 5, startAngle: Math.PI / 2})
const mypath = arc({center: [5, 5], radius: 5, startAngle: Math.PI, endAngle: Math.PI / 2, segments: 4})

Any number of points can be appended to a path, which produces a new path.

const { path2 } = require('@jscad/modeling').geometries
const { line } = require('@jscad/modeling').primitives
 
const mypath = line([[27, -22], [27, 22]])
const newpath = path2.appendPoints([[-27, 22], [-27, -27], [27, -22]], mypath)

An 'arc' can be appended to a path as well, which creates a series of line segments that simulate an 'arc'.

Defaults:

• radius : [0, 0]
• clockwise : false
• large : false
• segments : 32

Note: This implementation follows the SVG specifications.

const { path2 } = require('@jscad/modeling').geometries
 
let p1 = path2.create([[10,-20]])
p1 = path2.appendPoints([[27.5,-3.28125]], p1)
p1 = path2.appendArc({endpoint: [12.5, -22.96875], radius: [15, -19.6875]}, p1)

In addition, 'bézier' curves can be appended to a path, which creates a series of line segments that simulate a 'bézier' curve.

The 'bézier' curve starts at the last point in the given path, and ends at the last control point. The other control points are intermediate control points to transition the curve from start to end points. The first control point may be 'null' to ensure a smooth transition occurs between curves.

Note: This implementation follows the SVG specifications.

const { path2 } = require('@jscad/modeling').geometries
 
let p5 = path2.create([[10,-20]])
p5 = path2.appendBezier({controlPoints: [[10,-10],[25,-10],[25,-20]]}, p5)
p5 = path2.appendBezier({controlPoints: [null, [25,-30],[40,-30],[40,-20]]}, p5)

There are many ways to convert paths into to two dimensional shapes. The following provide some examples.

First, a two dimensional shape can be created from the points inside a path, but the path must be closed.

const { geom2, path2 } = require('@jscad/modeling').geometries
const { line } = require('@jscad/modeling').primitives
 
// create a closed path in shape of triangle
const mypath = line([[10, 10], [-10, 10], [-10, -10], [10, 10]])
const myshape = geom2.fromPoints(path2.toPoints(mypath))

Second, a path can be expanded into a two dimensional shape. The result is a two dimensional shape that fits around the path.

// create an open path in shape of L
const { expand } = require('@jscad/modeling').expansions
const { line } = require('@jscad/modeling').primitives
 
const mypath = line([[10, 10], [-10, 10], [-10, -10]])
const myshape = expand({delta: 2, corners: 'chamfer'}, mypath)

Two dimensional shapes can be extruded into three dimensional shapes.

const { path2 } = require('@jscad/modeling').geometries
const { extrudeLinear } = require('@jscad/modeling').extrusions
 
// create a closed path in shape of triangle
const mypath = path2.fromPoints({ closed: true }, [[0, 0], [12, 0], [6, 10]])
// extrude into triangular prism
const myshape = extrudeLinear({ height: 15 }, mypath)