nc://construct

Construct: one exact description of a thing becomes geometry you can look at, print and hand on -- a checked scene, a glTF, an OBJ, an STL and a page that turns. A Nodecode rewrite of rtmandreyev/construct by rtmandreyev.

A project is a folder with a scene.json in it: named parts, each of a shape (box, cylinder, cone, sphere) at a full size in metres, a centre, a rotation, and how it is known. The cell checks the scene, compiles it once into triangles and lines, and every output comes from that one compile, so the page, the model and the mesh cannot disagree. Nothing is downloaded, nothing is fetched at run time, and no Python, Node or browser is needed: the geometry is written here, and the page is one HTML file with its viewer inlined.

Get it

Tell the agent "add the construct cell", or run nodecode add nc://construct.

Set it up

Nothing is required: the projects live under the home's construct/ folder, and a cube is a size and a place away from being a thing.

Use it

Ask for a thing, and the model works in a project:

1. construct_start begins one -- cube, shed, or a whole scene you write as JSON.
2. construct_edit changes one part by its id: move, size, rotate, certainty, role, color, or remove. The whole scene is checked first, so a change that breaks it writes nothing and comes back with every problem; what did move comes back as the diff.
3. construct_check says what is wrong, each problem with its JSON path and the fix (parts[2].size: size 0,0,0 is outside ... -- metres; a part is at least 0.1 mm), and what the scene compiles to.
4. construct_inspect is what the record says is known: the parts by certainty, role and size, the overall size, and every fact with the source it came from.
5. construct_build writes build/index.html: the construct drawn in lines of light with pale faces, turning, drag to turn it, wheel to zoom, every part named and in its own colour. Open it in a browser.
6. construct_export writes export/construct.gltf with construct.bin, export/construct.obj and export/construct.stl (millimetres, as a slicer reads it), reads each one back and answers what it carries.

/construct lists the projects and what each checks to; /construct <slug> shows one and where its page is.

A scene in full:

{
  "format": "construct-scene",
  "version": 2,
  "name": "a shed",
  "category": "architecture",
  "sources": [{"id": "plan", "kind": "drawing", "title": "the plan"}],
  "facts": [{"text": "the shed is 3 m wide", "certainty": "verified", "source": "plan"}],
  "parts": [
    {"id": "floor", "shape": "box", "size": [3, 2.4, 0.1], "position": [0, 0, 0.05],
     "certainty": "inferred", "role": "mass", "color": "#8a7f6a"}
  ]
}

Size is the part's full extent in X, Y and Z, not half of it; position is its centre, not its corner; rotation is XYZ degrees about that centre; Z is up. A part with no certainty is inferred, and the page and the inspect both say so.

Test

.github/test-cell.sh tools/nodecode-construct

Everything in the slice is offline: the scenes are written by the test, and the geometry, the checks, the three exports and the page are proved from the files they leave on disk.

What is not here

The original also does CAD (FreeCAD, STEP, 3MF), films, model kits, headless review images, NetLogo runs drawn as constructs, and joints with animation, and it ships sixteen constructs and sixteen tutorials. Each needs a program or an engine this cell does not bundle. NOTICE says what was left out and why.

License

Apache-2.0, the original's. See LICENSE and NOTICE.