length.md

title	length
description	Read the actual arc length of an edge model or finite edge reference.
sourceReview	packageVersion sources 0.0.1-alpha.16 path sha256 packages/core/src/library/runtime.ts dcee3d2388a9b7b3819bb4897edd894463daa0e5b519e832a3349fac98c3bff8 path sha256 commit packages/core/src/library/topology.ts f9f0d048fe30cc80046a25123aa8101ca51e85cdb5b2e66260c6a68f43f84715 67228dd8559d584852df7bfbd47ed89f1d8003e9
sidebar	hidden true
head	tag content title length — Code3D TypeScript API reference

Read the actual arc length of an edge model or finite edge reference.

Example

import {arc, circle, group, line} from '@code3d/core';

const straight = line([0, 0, 0], [30, 40, 0]);
const curved = arc([20, 0, 0], [0, 20, 0], [-20, 0, 0]).originOffset(-60, 0, 0);
const ring = circle(18).originOffset(-115, 0, 0);

// Select each .length to inspect the measured edge and its read-only value.
const straightLength = straight.length; // 50
const arcLength = curved.length; // 20 * Math.PI, not the endpoint distance
const circumference = ring.edges()[0].length; // 36 * Math.PI

export default group([straight, curved, ring]);

Complete example: measurement example.

Signature

edgeModel.length: number;
edgeReference.length: number;

Import the functions and named types from @code3d/core.

Receivers and units

EdgeModel and Edge expose a readonly length. The value is a plain number in model units. A straight edge measures its endpoint distance; curves measure their actual path, including the whole circumference of a closed edge. For the example: straight length is 50, semicircle length is 20 * Math.PI, and the ring's single edge length is 36 * Math.PI.

A face model does not have a perimeter getter. Select its edges and sum their lengths when that is the desired measurement. Groups and generic LineAnchor references do not provide length: the latter may represent an infinite axis. Select finite edge geometry instead.

Transforms and references

Origin edits, rotations and placement preserve length. Positive uniform scaled multiplies it by the scale factor. Exposed edge references include the scale of their actual geometry. reverse changes reference direction without changing the length.

The result is computed when read; it does not update a previously assigned number when a new model value is constructed. Re-evaluating source reads the current value. Numerical measurements can differ from an analytic value by floating-point tolerance. No editable constraint is created by this getter.

Inspection

Select .length in App to highlight the measured finite path. Straight edges show an endpoint dimension; curves show an arc-length label. A curve's parameter midpoint need not be its half-length point. Use distance between start and end for the endpoint chord instead of the path length.