index.js

const {CSG} = require('@jscad/csg')
const stringify = require('onml/lib/stringify')

const mimeType = 'image/svg+xml'

const serialize = function (cagObject, options) {
  options && options.statusCallback && options.statusCallback({progress: 0})
  var decimals = 1000

  // mirror the CAG about the X axis in order to generate paths into the POSITIVE direction
  var plane = new CSG.Plane(CSG.Vector3D.Create(0, 1, 0), 0)
  var cag = cagObject.transform(CSG.Matrix4x4.mirroring(plane))

  var bounds = cag.getBounds()
  var paths = cag.getOutlinePaths()
  var width = Math.round((bounds[1].x - bounds[0].x) * decimals) / decimals
  var height = Math.round((bounds[1].y - bounds[0].y) * decimals) / decimals

  var body = ['svg',
    {
      width: width + 'mm',
      height: height + 'mm',
      viewBox: ('0 0 ' + width + ' ' + height),
      version: '1.1',
      baseProfile: 'tiny',
      xmlns: 'http://www.w3.org/2000/svg',
      'xmlns:xlink': 'http://www.w3.org/1999/xlink'
    },
    PathsToSvg(paths, bounds)
  ]

  var svg = `<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated by OpenJSCAD.org -->
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1 Tiny//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11-tiny.dtd">
${stringify(body)}`

  options && options.statusCallback && options.statusCallback({progress: 100})
  return [svg]
}

const PathsToSvg = function (paths, bounds, options) {
  // calculate offsets in order to create paths orientated from the 0,0 axis
  var xoffset = 0 - bounds[0].x
  var yoffset = 0 - bounds[0].y

  return paths.reduce(function (res, path, i) {
    options && options.statusCallback && options.statusCallback({progress: 100 * i / paths.length})
    return res.concat([['path', {d: dPath(path, xoffset, yoffset)}]])
  }, ['g'])
}

const dPath = function (path, xoffset, yoffset) {
  var pointindex
  var str = ''
  var numpointsClosed = path.points.length + (path.closed ? 1 : 0)
  for (pointindex = 0; pointindex < numpointsClosed; pointindex++) {
    var pointindexwrapped = pointindex
    if (pointindexwrapped >= path.points.length) pointindexwrapped -= path.points.length
    var point = path.points[pointindexwrapped]
    if (pointindex > 0) {
      str += `L${(point.x + xoffset)} ${(point.y + yoffset)}`
    } else {
      str += `M${(point.x + xoffset)} ${(point.y + yoffset)}`
    }
  }
  return str
}

module.exports = {
  serialize,
  mimeType
}