@jscad/modeling/src/measurements/measureVolume.js

Constructive Solid Geometry (CSG) Library for JSCAD

const flatten = require('../utils/flatten')

const geom2 = require('../geometries/geom2')
const geom3 = require('../geometries/geom3')
const path2 = require('../geometries/path2')
const poly3 = require('../geometries/poly3')

const cache = new WeakMap()

/*
 * Measure the volume of the given geometry.
 * NOTE: paths are infinitely narrow and do not have an volume
 *
 * @param {Path2} geometry - geometry to measure
 * @returns {Number} volume of the geometry
 */
const measureVolumeOfPath2 = () => 0

/*
 * Measure the volume of the given geometry.
 * NOTE: 2D geometry are infinitely thin and do not have an volume
 *
 * @param {Geom2} geometry - 2D geometry to measure
 * @returns {Number} volume of the geometry
 */
const measureVolumeOfGeom2 = () => 0

/*
 * Measure the volume of the given geometry.
 *
 * @param {Geom3} geometry - 3D geometry to measure
 * @returns {Number} volume of the geometry
 */
const measureVolumeOfGeom3 = (geometry) => {
  let volume = cache.get(geometry)
  if (volume) return volume

  const polygons = geom3.toPolygons(geometry)
  volume = polygons.reduce((volume, polygon) => volume + poly3.measureSignedVolume(polygon), 0)

  cache.set(geometry, volume)

  return volume
}

/**
 * Measure the volume of the given geometries.
 * @param {...Object} geometries - the geometries to measure
 * @return {Number|Array} the volume, or a list of volumes for each geometry
 * @alias module:modeling/measurements.measureVolume
 *
 * @example
 * let volume = measureVolume(sphere())
 */
const measureVolume = (...geometries) => {
  geometries = flatten(geometries)
  if (geometries.length === 0) throw new Error('wrong number of arguments')

  const results = geometries.map((geometry) => {
    if (path2.isA(geometry)) return measureVolumeOfPath2(geometry)
    if (geom2.isA(geometry)) return measureVolumeOfGeom2(geometry)
    if (geom3.isA(geometry)) return measureVolumeOfGeom3(geometry)
    return 0
  })
  return results.length === 1 ? results[0] : results
}

module.exports = measureVolume