---
title: "Chained path notation: API"
package: "@phaser-ae/path-notation"
tier: Free
version: 3.0.0-0
released: 2026-10-19
updated: 2026-10-19
description: "Routes written as plain data, a start point and a chain of lines, beziers, arcs, spirals and waves, baked so followers move at an even speed."
url: https://phaser.io/packs/path-notation/api
site: Phaser - https://phaser.io
---

# Chained path notation: API

`@phaser-ae/path-notation` — Routes authored as chained segments in plain data (lines, béziers, arcs, spirals, waves), eased and baked for even speed.

## The pack

### `pathNotation`

```ts
function pathNotation(): Pack<{ pathNotation: PathNotationApi }>
```

The `path-notation` pack: routes authored as chained segments in plain data, baked for even speed. Pure maths.

## Classes

### `Path`

```ts
class Path
```

A 2D path: curve segments chained into one constant-speed route, baked once.

```ts
const swoop = new Path({
  start: [400, 40],
  segments: [
    { cubic: [[300, 40], [220, 200], [120, 200]], ease: 'easeOutQuad' },
    { wave: { to: [-20, 120], amplitude: 18, cycles: 2 } },
  ],
});
const p = swoop.getPoint(0.5);          // halfway ALONG the route (by distance)
sprite.x = p.x; sprite.y = p.y;
sprite.rot = swoop.getAngle(0.5);       // facing its direction of travel
```

`getPoint(t)` is O(log samples) — a binary search over the baked table — so
hundreds of followers per frame are cheap.

- `readonly length: number` — Total geometric length of the path, in pixels.
- `constructor(data: PathData, options: PathOptions = {})`
- `static fromJSON(json: string | PathData, options: PathOptions = {}): Path` — Build a Path from a JSON string or an already-parsed data object.
- `getPoint(t: number, out: Vec2 = { x: 0, y: 0 }): Vec2` — The point at `t` (0 = start, 1 = end) measured BY DISTANCE along the path (constant speed unless eased). Pass `out` to avoid allocating.
- `getAngle(t: number): number` — The direction of travel at `t`, in radians (atan2 convention — feed it straight to `sprite.rot` so art faces along the path).

## Types

### `PathData`

```ts
interface PathData
```

The plain-data path notation — JSON-friendly: author it inline, in config
tables, or load it with `loadJson`.

- `start: PathPoint` — Where the path begins, `[x, y]`.
- `segments: PathSegmentData[]` — The chained segments, each continuing from the previous end point.
- `ease?: PathEase` — Ease applied across the WHOLE path's travel (on top of per-segment eases).

### `PathEase`

```ts
type PathEase = EaseName | EaseFn
```

An ease across a segment or a whole path: a name, or your own function.

### `PathNotationApi`

```ts
interface PathNotationApi
```

`game.pathNotation`: the chained path notation.

- `Path: typeof Path` — A route baked from its plain-data notation; `Path.fromJSON` takes a string too.

### `PathOptions`

```ts
interface PathOptions
```

Parse-time options — transform the authored coordinates once, at the bake.

- `flipX?: number` — Mirror every x about this vertical axis (`flipX: W / 2` flips a wave to the other side of the screen).
- `flipY?: number` — Mirror every y about this horizontal axis.
- `offset?: PathPoint` — Translate the whole path by `[dx, dy]`.
- `samplesPerSegment?: number` — Samples baked per segment (the arc-length table resolution). Default 48 — raise for very long or very curly segments.

### `PathPoint`

```ts
type PathPoint = [number, number]
```

A point in the data notation — `[x, y]`.

### `PathSegmentData`

```ts
interface PathSegmentData
```

One segment of the plain-data path notation. Every segment continues from the
path's current point; coordinates are absolute (transform at parse time via
{@link PathOptions}). Exactly one of the shape keys per segment.

- `line?: PathPoint` — Straight line to `[x, y]`.
- `quad?: [PathPoint, PathPoint]` — Quadratic bézier: `[control, to]`.
- `cubic?: [PathPoint, PathPoint, PathPoint]` — Cubic bézier: `[control1, control2, to]`.
- `arc?: { center: PathPoint; to: number; ry?: number }` — Elliptical arc about a centre. Starts at the current point (start angle and x-radius are derived from it); sweeps to absolute angle `to` (DEGREES — beyond ±360 keeps orbiting). `ry` defaults to the derived x-radius (circle).
- `spiral?: { center: PathPoint; turns: number; endRadius: number }` — Spiral about a centre: like `arc`, but the radius glides to `endRadius` over `turns` full revolutions (positive = clockwise, negative = counter).
- `wave?: { to: PathPoint; amplitude: number; cycles: number; shape?: 'sine' | 'triangle' }` — Sinusoidal wave: ride the straight chord to `to` while oscillating perpendicular by `amplitude` px over `cycles` full waves. `shape: 'triangle'` makes it a zigzag.
- `ease?: PathEase` — Ease applied across THIS segment's travel (name or function).

---

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