Measure and validate - OpenGeometry

Volume and area

body.measure({ deflection? }) returns { volume, area, errorBound, areaErrorBound, deflection }, in the body’s own coordinates. A scale in the placement is not applied.

import { OpenGeometry, Solid, OG_PRIMITIVE_CYLINDER, type Measure } from 'opengeometry';

await OpenGeometry.create(
  { wasmURL: '/opengeometry_bg.wasm' },
  { workerURL: '/tessellation-worker.js' },
);

const leg = new Solid(OG_PRIMITIVE_CYLINDER, { radius: 0.1, height: 0.7 });
const size: Measure = leg.measure({ deflection: 0.001 });
const exact = Math.PI * 0.1 * 0.1 * 0.7;
console.log(Math.abs(size.volume - exact) <= size.errorBound);

The values are approximate, with a stated bound:

|volume − exact| ≤ errorBound.
|area − exact| ≤ areaErrorBound.
A body with only flat faces measures exactly, within 1e-10 of its size.
A smaller deflection gives a smaller bound and a slower call. The default is 0.01.
A bound is Infinity when a triangle is too coarse to bound. JSON.stringify writes it as null.

A deflection that is not a positive finite number throws InvalidParameter. A mesh of more than 2 000 000 triangles throws LimitExceeded. The call does not change the document.

Validity

body.validity() returns { valid, closed, bodyType }, and error: { code, message } when the body is not valid.

import { OpenGeometry, Solid, OG_PRIMITIVE_CUBOID, type Validity } from 'opengeometry';

await OpenGeometry.create(
  { wasmURL: '/opengeometry_bg.wasm' },
  { workerURL: '/tessellation-worker.js' },
);

const box = new Solid(OG_PRIMITIVE_CUBOID, { width: 1, height: 1, depth: 1 });
const check: Validity = box.validity();
console.log(check);

A valid closed solid gives { valid: true, closed: true, bodyType: 'Solid' }. closed is true when every shell of a sheet or a solid is closed, and when every wire of a wire body is closed.

Point classification

body.classifyPoint([x, y, z]) says where a point is, in the body’s own coordinates: 'Inside', 'Outside', 'Boundary' or 'Unknown'.

import { OpenGeometry, Solid, OG_PRIMITIVE_CYLINDER, type PointClassification } from 'opengeometry';

await OpenGeometry.create(
  { wasmURL: '/opengeometry_bg.wasm' },
  { workerURL: '/tessellation-worker.js' },
);

const leg = new Solid(OG_PRIMITIVE_CYLINDER, { radius: 0.1, height: 0.7 });
const middle: PointClassification = leg.classifyPoint([0, 0.35, 0]);
const top: PointClassification = leg.classifyPoint([0, 0.7, 0]);
console.log(middle, top);

A point within 1e-8 of the surface is 'Boundary'.
A body is 'Inside' if any of its solids holds the point.
A wire or a sheet throws InvalidOperand.
Known limit: on a cylinder, cone or frustum that was mirrored, a point outside the body can read 'Inside'.
For a world point, first call OpenGeometry.flush(), then body.worldToLocal(new THREE.Vector3(x, y, z)).

Other queries

Call	Returns
`getBounds()`	`[minX, minY, minZ, maxX, maxY, maxZ]` in the world, or `null`
`getBrep()`	The B-rep in the body’s own coordinates: `topology` with faces, edges and vertices
`getWorldBrep()`	The same B-rep, placed in the world. It makes no body
`faceNormalAt(faceId, point)`	The face’s unit normal at a point, in the body’s own coordinates
`solid.getReport()`	The report of the last boolean, or `null`

To turn a normal into the world, call OpenGeometry.flush(), then use new THREE.Vector3(...normal).transformDirection(body.matrixWorld).

​Volume and area

​Validity

​Point classification

​Other queries

Volume and area

Validity

Point classification

Other queries