@jscad/modeling/src/geometries/poly3/measureSignedVolume.test.js

Constructive Solid Geometry (CSG) Library for JSCAD

const test = require('ava')

const { measureSignedVolume, create, invert, fromPoints, transform } = require('./index')

const mat4 = require('../../maths/mat4')

const { nearlyEqual } = require('../../../test/helpers/index')

test('poly3: measureSignedVolume() should return correct values', (t) => {
  let ply1 = create()
  let ret1 = measureSignedVolume(ply1)
  nearlyEqual(t, ret1, 0.0, Number.EPSILON)

  // simple triangle
  let ply2 = fromPoints([[5, 5, 5], [5, 15, 5], [5, 15, 15]])
  let ret2 = measureSignedVolume(ply2)
  nearlyEqual(t, ret2, 83.33333333333333, Number.EPSILON)

  // simple square
  let ply3 = fromPoints([[5, 5, 5], [5, 15, 5], [5, 15, 15], [5, 5, 15]])
  let ret3 = measureSignedVolume(ply3)
  nearlyEqual(t, ret3, 166.66666666666666, Number.EPSILON)

  // V-shape
  const points = [
    [-50, 3, 0],
    [-50, 5, 0],
    [-50, 8, 2],
    [-50, 6, 5],
    [-50, 8, 6],
    [-50, 5, 6],
    [-50, 5, 2],
    [-50, 2, 5],
    [-50, 1, 3],
    [-50, 3, 3]
  ]
  let ply4 = fromPoints(points)
  let ret4 = measureSignedVolume(ply4)
  nearlyEqual(t, ret4, -325.00000, Number.EPSILON)

  // rotated to various angles
  const rotation = mat4.fromZRotation(mat4.create(), (45 * 0.017453292519943295))
  ply1 = transform(rotation, ply1)
  ply2 = transform(rotation, ply2)
  ply3 = transform(rotation, ply3)
  ply4 = transform(rotation, ply4)
  ret1 = measureSignedVolume(ply1)
  ret2 = measureSignedVolume(ply2)
  ret3 = measureSignedVolume(ply3)
  ret4 = measureSignedVolume(ply4)
  nearlyEqual(t, ret1, 0.0, Number.EPSILON)
  nearlyEqual(t, ret2, 83.33333333333331, Number.EPSILON)
  nearlyEqual(t, ret3, 166.66666666666663, Number.EPSILON)
  nearlyEqual(t, ret4, -324.9999999999994, Number.EPSILON)

  // inverted (opposite rotation, normal)
  ply2 = invert(ply2)
  ply3 = invert(ply3)
  ply4 = invert(ply4)
  ret2 = measureSignedVolume(ply2)
  ret3 = measureSignedVolume(ply3)
  ret4 = measureSignedVolume(ply4)
  nearlyEqual(t, ret2, -83.33333333333331, Number.EPSILON)
  nearlyEqual(t, ret3, -166.66666666666663, Number.EPSILON)
  nearlyEqual(t, ret4, 324.9999999999994, Number.EPSILON)

  t.true(true)
})