Glossary

The words these pages use, in alphabetical order. Each links to the page that explains it further. How Bitbybit works puts most of them together.

API

The functions under bitbybit, such as bitbybit.occt.fillets.filletEdges, which every editor, runner and package calls. A Rete component, a Blockly block and a TypeScript call with the same name are the same function. Code maps it.

Assembly

Parts placed together with names and colours, kept in a document that a STEP file can carry and other CAD programs read. Assemblies; in the Designer, components and joints.

Asset

The word has three uses:

• A file in a project, such as a STEP model, a font or an image, that its scripts load, kept in the cloud or in this browser and moved with the project. The editor's browser asset catalog keeps files for every project in this browser, for quick tests. Assets.
• bitbybit.asset, the open-source functions that load such files, fetch files from a URL and start downloads.
• In 3D Bits, the 3D models a merchant uploads for the storefront.

Await

Kernel calls take time and run in a worker, so in TypeScript each returns a promise you await before using its result. Rete components and Blockly blocks wait for you.

B-rep

Boundary representation: a solid described by the exact surfaces and curves that bound it, as OpenCascade keeps it, rather than by triangles. It is why a fillet stays round and a STEP file stays exact.

BabylonJS, ThreeJS, PlayCanvas

The three 3D engines Bitbybit draws with. The editors on bitbybit.dev use BabylonJS; the npm packages and runners come in all three. Game engines.

Blockly

The editor where you build a script by snapping blocks together. Blockly.

CAD Cloud

Bitbybit's servers, which run geometry through a REST API, a TypeScript SDK and an MCP server, and return STEP, glTF or mesh files. CAD Cloud API.

Code component

A Rete component that holds a TypeScript function, for the few lines where code says more than nodes. Code components.

Community

Who may open a shared project: everyone (public), or members of the Silver or Gold plan. Projects.

Component

In Rete, one node of the graph: a function with its inputs on the left and its outputs on the right. In the Designer, a part or sub-assembly placed in an assembly.

Composer

The 3D Bits tool for building a Shopify product's 3D viewer and configurator without code. Composer.

Compound

A group of OpenCascade shapes kept together as one shape but not joined, drawn and moved at once. Compounds.

Converter

The bitbybit.dev tool that turns STEP files into glTF in your browser, for Silver and Gold members. CAD Cloud converts in bulk. Converter.

Design document

The JSON the Designer keeps a part or an assembly in: its parameters, sketches, features and joints, in order. Agents can write one, and bitbybit.occt.design.build builds it. Design documents.

Designer

Bitbybit's parametric CAD modeller, where you build by clicking: sketches, features, parts and assemblies with joints, every step editable. Part of the Gold plan. The Designer.

Draw

Turning geometry into a mesh a 3D engine shows. A shape is computed whether or not it is drawn, and the drawing never changes the shape. Drawing, the draw functions.

Edge, wire, face, shell, solid

The kinds of OpenCascade shape, from small to large: an edge is a curve between two vertices, a wire a chain of edges, a face a surface bounded by wires, a shell faces joined at their edges, and a solid the volume a closed shell bounds. OCCT shapes.

Export to runner

Turning an editor's script into JavaScript a runner executes on another website. Runners.

glTF, GLB

The standard format for 3D models on the web, with meshes, materials and animations; GLB is its single-file form. Bitbybit draws, imports and exports it.

IFC

The open format of building models (BIM). bitbybit.ifc reads, writes and authors it. IFC.

Inspector

The bitbybit.dev tool for looking inside glTF, GLB and STL files, for Silver and Gold members. 3D inspector.

JSCAD

A kernel that builds solids from polygons, good for quick shapes and 3D text. It builds along Z. How it works.

Kernel

The library that computes geometry. Bitbybit runs OpenCascade, Manifold, JSCAD and an IFC library, compiled to WebAssembly. The kernels.

Manifold

A mesh kernel whose booleans are fast and always give a closed solid, for thousands of cuts, lattices and scanned meshes. It builds along Z. How it works.

MCP

Model Context Protocol, the way AI agents connect to tools. The Bitbybit CAD MCP answers questions about the API; the CAD Cloud MCP runs geometry on CAD Cloud. Using AI.

Mesh

A surface made of triangles: what every engine draws, what Manifold computes with, and what STL files hold.

Module

The word has three uses:

• A Rete module: part of a graph packaged with its own inputs and outputs and used as a component, many times. Modules.
• A TypeScript file that other files import from. Files and imports.
• In JavaScript tooling, an ES module an npm package ships as.

npm packages

Bitbybit's open-source libraries, @bitbybit-dev/*, for your own web app or Node service. npm packages.

OCCT, OpenCascade

The exact CAD kernel under most of Bitbybit's modelling: solids, fillets, booleans, STEP and IGES. What is OCCT.

Platform algorithms

The bitbybit.advanced and bitbybit.things functions, closed source, which run on bitbybit.dev and in the runners; some need the Silver or Gold plan. Tools that list the API call them platform-pro. Plans.

Preview

The page that shows a published script's result without its editor, and the address an embed frames on another website. Publishing.

Project

What holds your work on bitbybit.dev: scripts and the files they use, kept in the cloud or in this browser. Projects.

Rete

The editor where you wire nodes into a graph that reruns as you change it. Rete.

Runner

One JavaScript file that carries the kernels and an engine, so a script made in an editor, or code you write, runs on any web page from a <script> tag. Runners.

Script

One piece of work in a project, written in one editor: a Rete graph, a Blockly workspace, TypeScript files or a Designer design. Scripts.

Shape, shape handle

What an OpenCascade, Manifold or JSCAD function returns. In a browser the kernel keeps the shape in its worker and your code holds a handle, { hash, type }, that it passes to the next call. How it works.

STEP, IGES, BREP

CAD file formats that keep exact geometry. STEP is the one most CAD programs exchange, and it can carry assemblies with names and colours; BREP is OpenCascade's own. STEP and IGES.

STL

A mesh file of triangles, the usual format for 3D printing.

Studio

Bitbybit Studio, the dashboard of CAD Cloud, where you get API keys, try operations and follow tasks. Studio.

Task

One CAD Cloud job: submitted, then followed until its result is ready to download. CAD Cloud API.

Tolerance, precision

How close is close enough. A kernel's tolerance decides when two points are the same; a drawing's precision decides how finely a curve is divided into triangles. Neither is a modelling dimension.

TypeScript editor

The editor where you write code against the whole API, in many files, with IntelliSense. It is built on Monaco, the editor of Visual Studio Code. TypeScript.

Vertex

An OpenCascade point that belongs to a shape, at the ends of its edges. A plain point is just [x, y, z].

Web worker

A background thread of the browser. Each kernel runs in one, so long calculations never freeze the page. How it works.

WebAssembly

The format that lets compiled C++ run in a browser at close to native speed. The kernels are compiled to it.

3D Bits

Bitbybit's Shopify app, which puts 3D viewers and product configurators on product pages. 3D Bits.