toByteArray produces invalid 3dm file in some cases

Here’s a simple node.js script that produces an invalid .3dm file.

The script solves a simple Grasshopper definition on Compute (see below) that produces a very simple mesh box and then adds that mesh to a doc and writes it to “box_test.3dm”.

Uncomment the line to also add the sphere to the doc. In this case the .3dm file will be valid and the mesh box will be present and valid.

const rhino3dm = require('rhino3dm')
const compute = require('compute-rhino3d')
const fs = require('fs')

compute.url = 'http://localhost:8081/'

const name = 'box_test.gh'

const buffer = fs.readFileSync(name)
const definition = new Uint8Array(buffer)

async function doStuff() {
    const rhino = await rhino3dm()
    let res = await compute.Grasshopper.evaluateDefinition(definition, [])

    const json = JSON.parse(res.values[0].InnerTree['{ 0; }'][0].data)
    const mesh = rhino.CommonObject.decode(json)

    const doc = new rhino.File3dm()
    doc.objects().add(mesh, null)

    const sphere = new rhino.Sphere([0,0,0], 12)
    
    // add this sphere and the 3dm file will be valid!
    //doc.objects().addSphere(sphere, null)

    console.log('saved')
    fs.writeFileSync('box_test.3dm', doc.toByteArray())
}

doStuff()

box_test.zip

[fraguada]

Got around to testing the changes by @kovacsv and this bug is no longer present in js.

[fraguada]

@pearswj @sbaer here is another case of this issue popping up: https://discourse.mcneel.com/t/rhino3dm-threejs-geometry-import-failing/118635/6