Quick start

GeoSpec, geometry specifications for CAD: state what a model must be, and the engine measures the delivered geometry and answers passed, failed or refused. A claim the engine cannot decide on the given geometry is refused with a typed reason, never passed.

Install

npm i geospec-engine@next

Every commit on main publishes a next prerelease. Node 24 or later is required. See Install for the native addon and the Python wheel.

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The engine exchanges JSON request bytes and binary geometry bytes. This script builds a 10 × 20 × 30 mm box, admits it, and claims its bounding box:

quick-start.mjs

import { createHash } from 'node:crypto';
import { Engine, initialize } from 'geospec-engine';

// A 10 × 20 × 30 mm box in mesh-buffer-v1: 'GSM1', two u32 counts,
// f64 vertex coordinates, then u32 triangle indices, all little-endian.
const vertices = [0, 1, 2, 3, 4, 5, 6, 7].map((i) => [(i & 1) * 10, ((i >> 1) & 1) * 20, ((i >> 2) & 1) * 30]);
const triangles = [
  [0, 2, 1],
  [1, 2, 3],
  [4, 5, 6],
  [5, 7, 6],
  [0, 1, 4],
  [1, 5, 4],
  [2, 6, 3],
  [3, 6, 7],
  [0, 4, 2],
  [2, 4, 6],
  [1, 3, 5],
  [3, 7, 5],
];
const mesh = new Uint8Array(12 + vertices.length * 24 + triangles.length * 12);
const view = new DataView(mesh.buffer);
mesh.set(new TextEncoder().encode('GSM1'));
view.setUint32(4, vertices.length, true);
view.setUint32(8, triangles.length, true);
vertices.flat().forEach((value, index) => view.setFloat64(12 + index * 8, value, true));
const indexStart = 12 + vertices.length * 24;
triangles.flat().forEach((value, index) => view.setUint32(indexStart + index * 4, value, true));

const encode = (value) => new TextEncoder().encode(JSON.stringify(value));
const decode = (bytes) => JSON.parse(new TextDecoder().decode(bytes));
const header = { protocolVersion: 3, registryVersion: 5, canonicalProfile: 'geospec-jcs-v1' };
const contentHash = createHash('sha256').update(mesh).digest('hex');

await initialize(); // loads the WASM module shipped in the package
const engine = new Engine();
engine.ingestMesh(
  encode({
    method: 'ingestSubject',
    requestId: 'ingest',
    ...header,
    contentHash,
    format: 'mesh-buffer-v1',
    frame: { coordinateSystem: 'z-up', unit: 'mm' },
  }),
  mesh,
);
const response = decode(
  engine.processRequest(
    encode({
      method: 'submitClaims',
      requestId: 'size',
      ...header,
      plan: {
        subjects: [{ slot: 'part', contentHash }],
        claims: [
          {
            claimId: 'size',
            capability: 'toHaveBoundingBox',
            subjectSlots: ['part'],
            polarity: 'positive',
            workUnitBudget: 100,
            payload: { kind: 'boundingBox', expected: { size: { x: 10, y: 20, z: 30 } } },
          },
        ],
      },
    }),
  ),
);
engine.close();
console.log(response.result.results[0].status); // passed

node quick-start.mjs

The tutorial adds a failing and a refused claim to the same box.
How it works explains subjects, plans and results.
The geospec package wraps these bytes in expectGeo assertions; the API reference lists what the engine package exports.

Install

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