@jscad/modeling/src/maths/line3/closestPoint.js

Constructive Solid Geometry (CSG) Library for JSCAD

const vec3 = require('../vec3')

/**
 * Determine the closest point on the given line to the given point.
 *
 * @param {line3} line - line of reference
 * @param {vec3} point - point of reference
 * @returns {vec3} a point
 * @alias module:modeling/maths/line3.closestPoint
 */
const closestPoint = (line, point) => {
  const lpoint = line[0]
  const ldirection = line[1]

  const a = vec3.dot(vec3.subtract(vec3.create(), point, lpoint), ldirection)
  const b = vec3.dot(ldirection, ldirection)
  const t = a / b

  const closestpoint = vec3.scale(vec3.create(), ldirection, t)
  vec3.add(closestpoint, closestpoint, lpoint)
  return closestpoint
}

module.exports = closestPoint