@jscad/modeling/src/geometries/poly2/measureArea.test.js

Constructive Solid Geometry (CSG) Library for JSCAD

const test = require('ava')

const { measureArea, create } = require('./index')

test('poly2: measureArea() should return correct values', (t) => {
  const ply1 = create()
  const ret1 = measureArea(ply1)
  t.is(ret1, 0.0)

  // simple triangle
  let ply2 = create([[0, 0], [10, 0], [10, 10]])
  let ret2 = measureArea(ply2)
  t.is(ret2, 50.0)

  ply2 = create([[10, 10], [10, 0], [0, 0]])
  ret2 = measureArea(ply2)
  t.is(ret2, -50.0)

  // simple square
  let ply3 = create([[0, 0], [10, 0], [10, 10], [0, 10]])
  let ret3 = measureArea(ply3)
  t.is(ret3, 100.0)

  ply3 = create([[0, 10], [10, 10], [10, 0], [0, 0]])
  ret3 = measureArea(ply3)
  t.is(ret3, -100.0)

  // V-shape
  const points = [
    [3, 0],
    [5, 0],
    [8, 2],
    [6, 5],
    [8, 6],
    [5, 6],
    [5, 2],
    [2, 5],
    [1, 3],
    [3, 3]
  ]
  const ply4 = create(points)
  const ret4 = measureArea(ply4)
  t.is(ret4, 19.5)
})