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• About
• Status
• Related packages
• Installation
• Dependencies
• Usage examples
• API
  • Cubic curve conversion from polygons & polylines
    • Poly vertices as control points
    • Poly vertices as break points
• Authors
• License

About

nD cubic & quadratic curve analysis, conversion, interpolation, splitting. This is a support package for @thi.ng/geom.

Current implementations partially based on toxiclibs (Java) and Clojure version of thi.ng/geom.

Status

STABLE - used in production

Search or submit any issues for this package

Related packages

• @thi.ng/geom-subdiv-curve - Freely customizable, iterative nD subdivision curves for open / closed geometries

Installation

yarn add @thi.ng/geom-splines

ESM import:

import * as gs from "@thi.ng/geom-splines";

Browser ESM import:

<script type="module" src="https://esm.run/@thi.ng/geom-splines"></script>

JSDelivr documentation

For Node.js REPL:

const gs = await import("@thi.ng/geom-splines");

Package sizes (brotli'd, pre-treeshake): ESM: 2.79 KB

Dependencies

• @thi.ng/api
• @thi.ng/checks
• @thi.ng/geom-arc
• @thi.ng/geom-resample
• @thi.ng/math
• @thi.ng/vectors

Note: @thi.ng/api is in most cases a type-only import (not used at runtime)

Usage examples

One project in this repo's /examples directory is using this package:

Screenshot	Description	Live demo	Source
	Polygon to cubic curve conversion & visualization	Demo	Source

API

Generated API docs

Cubic curve conversion from polygons & polylines

Currently, there're two ways to convert a polygon/polyline into a sequence of cubic curve segments. Both modes support customizable curve tightness.

Furthermore, both conversion modes can be instructed to use uniformly scaled control point tangents: In uniform mode, the tangents have a uniform, user defined length, resulting in equidistant control points for each poly vertex. In non-uniform mode, each tangent is scaled by the length of its parent poly edge.

Poly vertices as control points

In this mode the curve always goes through the midpoints each polygon edge, with the original polygon vertices being used to compute control points.

Proportional tangent scale	Uniform tangent scale

Poly vertices as break points

In this mode the curve always goes through the original polygon vertices and additional control points are created via symmetric tangents at each poly vertex. The tangents themselves are computed via the bisector of each vertex corner, taking into the convexity of each poly vertex.

Proportional tangent scale	Uniform tangent scale

Authors

• Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-geom-splines,
  title = "@thi.ng/geom-splines",
  author = "Karsten Schmidt",
  note = "https://thi.ng/geom-splines",
  year = 2016
}

License

© 2016 - 2025 Karsten Schmidt // Apache License 2.0