regular-polygon.md

title	regularPolygon
description	Create a filled regular polygon in TypeScript with Code3D. Learn circumradius, side count, Y-axis rotation, inradius, area and local bounds.
sourceReview	packageVersion sources 0.0.1-alpha.14 path sha256 packages/core/src/library/regular-polygon.ts 06880f0103927de24bf0ba80036ea032b34bc92dbd1fe11d5b60d7ee85031c59 path sha256 packages/core/src/library/validation.ts dae9300aea522c8aee83ef09e6716f31cd17f0cf6fb6df537218ecb72c63419d path sha256 packages/core/src/library/planar-face-model.ts 75e2238441da9e4b097ea229dec22947f165601bb1266e3731f791837a531f65
sidebar	hidden true
head	tag content title regularPolygon() — Code3D TypeScript API reference

Create a filled regular polygonal face with a chosen number of equal sides. Use it as a cross-section for polygonal parts, lofts or extrusions.

Example

import {regularPolygon} from '@code3d/core';

export const pentagonalFace = regularPolygon(6, 5);

Select pentagonalFace in the App to inspect the geometry.

Complete example: basic shapes.

Signature

function regularPolygon(
  radius: number,
  sides: number,
  rotation?: number,
): FaceModel;

Import the function and any named types above from @code3d/core. The same call works in the App and Node; Node initializes the kernel automatically.

Parameters

Parameter	Meaning	Accepted values
radius	Circumradius, from polygon center to a vertex	Positive finite number
sides	Number of equal sides	Integer at least 3
rotation	Rotation about local +Y, in degrees	Finite number; defaults to 0

Radius uses the model's common length units. It is not the inradius or the full width across flats. Only rotation is optional in TypeScript; signed angles and angles beyond one turn are accepted.

Result and coordinates

The result is a FaceModel<PlanarElements> in the XZ plane at y = 0, facing +Y. It has sides straight boundary edges and vertices. The model origin is the polygon center. At zero rotation, one vertex is [0, 0, radius]; positive rotation about +Y turns that vertex toward +X.

.plane references the supporting plane. .center is the bounding-box center, which can differ from the polygon center for odd side counts. For the example, the bounds are approximately [-5.706339, 0, -4.854102] to [5.706339, 0, 6], so .center has Z approximately 0.572949 while the origin remains zero. A rotation changes the axis-aligned bounding box.

.originCenter() chooses the current bounding-box center as the new origin; it does not mean "put the circumcenter at zero". See local coordinates.

Measurements and extrusion

For n = sides and r = radius:

Quantity	Formula
Side length	2 * r * Math.sin(Math.PI / n)
Inradius	r * Math.cos(Math.PI / n)
Area	n * r ** 2 * Math.sin(2 * Math.PI / n) / 2

For even side counts, the distance across opposite parallel sides is twice the inradius. Odd polygons have no opposite parallel side pairs; do not use that formula as their axis-aligned width.

The example's .area is approximately 85.595086. The face has no .volume. .extrude(distance) builds a solid from the starting plane along its normal; regularPrism directly constructs a prism whose height is centered around zero. See profile operations.

Validation and editing defaults

A nonpositive or nonfinite radius is rejected. Noninteger side counts or values below 3 report sides must be an integer greater than or equal to 3. Nonfinite angles report rotation must be a finite number. Extremely small features can also encounter the modeling kernel's tolerance.

Incomplete calls use radius = 5, sides = 6 and rotation = 0 for omitted or undefined arguments. This does not remove the two required TypeScript arguments. Select an argument and press Tab to edit it in the App.

Related APIs

• regularPrism creates a centered polygonal solid.
• circle creates a smooth circular profile.
• rectangle uses full X and Z dimensions.
• Model values covers shared face capabilities.