StackGenVis/frontend/node_modules/gl-matrix/cjs/vec3.js

"use strict";

function _typeof(obj) { "@babel/helpers - typeof"; if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.create = create;
exports.clone = clone;
exports.length = length;
exports.fromValues = fromValues;
exports.copy = copy;
exports.set = set;
exports.add = add;
exports.subtract = subtract;
exports.multiply = multiply;
exports.divide = divide;
exports.ceil = ceil;
exports.floor = floor;
exports.min = min;
exports.max = max;
exports.round = round;
exports.scale = scale;
exports.scaleAndAdd = scaleAndAdd;
exports.distance = distance;
exports.squaredDistance = squaredDistance;
exports.squaredLength = squaredLength;
exports.negate = negate;
exports.inverse = inverse;
exports.normalize = normalize;
exports.dot = dot;
exports.cross = cross;
exports.lerp = lerp;
exports.hermite = hermite;
exports.bezier = bezier;
exports.random = random;
exports.transformMat4 = transformMat4;
exports.transformMat3 = transformMat3;
exports.transformQuat = transformQuat;
exports.rotateX = rotateX;
exports.rotateY = rotateY;
exports.rotateZ = rotateZ;
exports.angle = angle;
exports.zero = zero;
exports.str = str;
exports.exactEquals = exactEquals;
exports.equals = equals;
exports.forEach = exports.sqrLen = exports.len = exports.sqrDist = exports.dist = exports.div = exports.mul = exports.sub = void 0;

var glMatrix = _interopRequireWildcard(require("./common.js"));

function _getRequireWildcardCache() { if (typeof WeakMap !== "function") return null; var cache = new WeakMap(); _getRequireWildcardCache = function _getRequireWildcardCache() { return cache; }; return cache; }

function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } if (obj === null || _typeof(obj) !== "object" && typeof obj !== "function") { return { "default": obj }; } var cache = _getRequireWildcardCache(); if (cache && cache.has(obj)) { return cache.get(obj); } var newObj = {}; var hasPropertyDescriptor = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) { var desc = hasPropertyDescriptor ? Object.getOwnPropertyDescriptor(obj, key) : null; if (desc && (desc.get || desc.set)) { Object.defineProperty(newObj, key, desc); } else { newObj[key] = obj[key]; } } } newObj["default"] = obj; if (cache) { cache.set(obj, newObj); } return newObj; }

/**
 * 3 Dimensional Vector
 * @module vec3
 */

/**
 * Creates a new, empty vec3
 *
 * @returns {vec3} a new 3D vector
 */
function create() {
  var out = new glMatrix.ARRAY_TYPE(3);

  if (glMatrix.ARRAY_TYPE != Float32Array) {
    out[0] = 0;
    out[1] = 0;
    out[2] = 0;
  }

  return out;
}
/**
 * Creates a new vec3 initialized with values from an existing vector
 *
 * @param {vec3} a vector to clone
 * @returns {vec3} a new 3D vector
 */


function clone(a) {
  var out = new glMatrix.ARRAY_TYPE(3);
  out[0] = a[0];
  out[1] = a[1];
  out[2] = a[2];
  return out;
}
/**
 * Calculates the length of a vec3
 *
 * @param {vec3} a vector to calculate length of
 * @returns {Number} length of a
 */


function length(a) {
  var x = a[0];
  var y = a[1];
  var z = a[2];
  return Math.hypot(x, y, z);
}
/**
 * Creates a new vec3 initialized with the given values
 *
 * @param {Number} x X component
 * @param {Number} y Y component
 * @param {Number} z Z component
 * @returns {vec3} a new 3D vector
 */


function fromValues(x, y, z) {
  var out = new glMatrix.ARRAY_TYPE(3);
  out[0] = x;
  out[1] = y;
  out[2] = z;
  return out;
}
/**
 * Copy the values from one vec3 to another
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the source vector
 * @returns {vec3} out
 */


function copy(out, a) {
  out[0] = a[0];
  out[1] = a[1];
  out[2] = a[2];
  return out;
}
/**
 * Set the components of a vec3 to the given values
 *
 * @param {vec3} out the receiving vector
 * @param {Number} x X component
 * @param {Number} y Y component
 * @param {Number} z Z component
 * @returns {vec3} out
 */


function set(out, x, y, z) {
  out[0] = x;
  out[1] = y;
  out[2] = z;
  return out;
}
/**
 * Adds two vec3's
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {vec3} out
 */


function add(out, a, b) {
  out[0] = a[0] + b[0];
  out[1] = a[1] + b[1];
  out[2] = a[2] + b[2];
  return out;
}
/**
 * Subtracts vector b from vector a
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {vec3} out
 */


function subtract(out, a, b) {
  out[0] = a[0] - b[0];
  out[1] = a[1] - b[1];
  out[2] = a[2] - b[2];
  return out;
}
/**
 * Multiplies two vec3's
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {vec3} out
 */


function multiply(out, a, b) {
  out[0] = a[0] * b[0];
  out[1] = a[1] * b[1];
  out[2] = a[2] * b[2];
  return out;
}
/**
 * Divides two vec3's
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {vec3} out
 */


function divide(out, a, b) {
  out[0] = a[0] / b[0];
  out[1] = a[1] / b[1];
  out[2] = a[2] / b[2];
  return out;
}
/**
 * Math.ceil the components of a vec3
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a vector to ceil
 * @returns {vec3} out
 */


function ceil(out, a) {
  out[0] = Math.ceil(a[0]);
  out[1] = Math.ceil(a[1]);
  out[2] = Math.ceil(a[2]);
  return out;
}
/**
 * Math.floor the components of a vec3
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a vector to floor
 * @returns {vec3} out
 */


function floor(out, a) {
  out[0] = Math.floor(a[0]);
  out[1] = Math.floor(a[1]);
  out[2] = Math.floor(a[2]);
  return out;
}
/**
 * Returns the minimum of two vec3's
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {vec3} out
 */


function min(out, a, b) {
  out[0] = Math.min(a[0], b[0]);
  out[1] = Math.min(a[1], b[1]);
  out[2] = Math.min(a[2], b[2]);
  return out;
}
/**
 * Returns the maximum of two vec3's
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {vec3} out
 */


function max(out, a, b) {
  out[0] = Math.max(a[0], b[0]);
  out[1] = Math.max(a[1], b[1]);
  out[2] = Math.max(a[2], b[2]);
  return out;
}
/**
 * Math.round the components of a vec3
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a vector to round
 * @returns {vec3} out
 */


function round(out, a) {
  out[0] = Math.round(a[0]);
  out[1] = Math.round(a[1]);
  out[2] = Math.round(a[2]);
  return out;
}
/**
 * Scales a vec3 by a scalar number
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the vector to scale
 * @param {Number} b amount to scale the vector by
 * @returns {vec3} out
 */


function scale(out, a, b) {
  out[0] = a[0] * b;
  out[1] = a[1] * b;
  out[2] = a[2] * b;
  return out;
}
/**
 * Adds two vec3's after scaling the second operand by a scalar value
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @param {Number} scale the amount to scale b by before adding
 * @returns {vec3} out
 */


function scaleAndAdd(out, a, b, scale) {
  out[0] = a[0] + b[0] * scale;
  out[1] = a[1] + b[1] * scale;
  out[2] = a[2] + b[2] * scale;
  return out;
}
/**
 * Calculates the euclidian distance between two vec3's
 *
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {Number} distance between a and b
 */


function distance(a, b) {
  var x = b[0] - a[0];
  var y = b[1] - a[1];
  var z = b[2] - a[2];
  return Math.hypot(x, y, z);
}
/**
 * Calculates the squared euclidian distance between two vec3's
 *
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {Number} squared distance between a and b
 */


function squaredDistance(a, b) {
  var x = b[0] - a[0];
  var y = b[1] - a[1];
  var z = b[2] - a[2];
  return x * x + y * y + z * z;
}
/**
 * Calculates the squared length of a vec3
 *
 * @param {vec3} a vector to calculate squared length of
 * @returns {Number} squared length of a
 */


function squaredLength(a) {
  var x = a[0];
  var y = a[1];
  var z = a[2];
  return x * x + y * y + z * z;
}
/**
 * Negates the components of a vec3
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a vector to negate
 * @returns {vec3} out
 */


function negate(out, a) {
  out[0] = -a[0];
  out[1] = -a[1];
  out[2] = -a[2];
  return out;
}
/**
 * Returns the inverse of the components of a vec3
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a vector to invert
 * @returns {vec3} out
 */


function inverse(out, a) {
  out[0] = 1.0 / a[0];
  out[1] = 1.0 / a[1];
  out[2] = 1.0 / a[2];
  return out;
}
/**
 * Normalize a vec3
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a vector to normalize
 * @returns {vec3} out
 */


function normalize(out, a) {
  var x = a[0];
  var y = a[1];
  var z = a[2];
  var len = x * x + y * y + z * z;

  if (len > 0) {
    //TODO: evaluate use of glm_invsqrt here?
    len = 1 / Math.sqrt(len);
  }

  out[0] = a[0] * len;
  out[1] = a[1] * len;
  out[2] = a[2] * len;
  return out;
}
/**
 * Calculates the dot product of two vec3's
 *
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {Number} dot product of a and b
 */


function dot(a, b) {
  return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}
/**
 * Computes the cross product of two vec3's
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @returns {vec3} out
 */


function cross(out, a, b) {
  var ax = a[0],
      ay = a[1],
      az = a[2];
  var bx = b[0],
      by = b[1],
      bz = b[2];
  out[0] = ay * bz - az * by;
  out[1] = az * bx - ax * bz;
  out[2] = ax * by - ay * bx;
  return out;
}
/**
 * Performs a linear interpolation between two vec3's
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @param {Number} t interpolation amount, in the range [0-1], between the two inputs
 * @returns {vec3} out
 */


function lerp(out, a, b, t) {
  var ax = a[0];
  var ay = a[1];
  var az = a[2];
  out[0] = ax + t * (b[0] - ax);
  out[1] = ay + t * (b[1] - ay);
  out[2] = az + t * (b[2] - az);
  return out;
}
/**
 * Performs a hermite interpolation with two control points
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @param {vec3} c the third operand
 * @param {vec3} d the fourth operand
 * @param {Number} t interpolation amount, in the range [0-1], between the two inputs
 * @returns {vec3} out
 */


function hermite(out, a, b, c, d, t) {
  var factorTimes2 = t * t;
  var factor1 = factorTimes2 * (2 * t - 3) + 1;
  var factor2 = factorTimes2 * (t - 2) + t;
  var factor3 = factorTimes2 * (t - 1);
  var factor4 = factorTimes2 * (3 - 2 * t);
  out[0] = a[0] * factor1 + b[0] * factor2 + c[0] * factor3 + d[0] * factor4;
  out[1] = a[1] * factor1 + b[1] * factor2 + c[1] * factor3 + d[1] * factor4;
  out[2] = a[2] * factor1 + b[2] * factor2 + c[2] * factor3 + d[2] * factor4;
  return out;
}
/**
 * Performs a bezier interpolation with two control points
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the first operand
 * @param {vec3} b the second operand
 * @param {vec3} c the third operand
 * @param {vec3} d the fourth operand
 * @param {Number} t interpolation amount, in the range [0-1], between the two inputs
 * @returns {vec3} out
 */


function bezier(out, a, b, c, d, t) {
  var inverseFactor = 1 - t;
  var inverseFactorTimesTwo = inverseFactor * inverseFactor;
  var factorTimes2 = t * t;
  var factor1 = inverseFactorTimesTwo * inverseFactor;
  var factor2 = 3 * t * inverseFactorTimesTwo;
  var factor3 = 3 * factorTimes2 * inverseFactor;
  var factor4 = factorTimes2 * t;
  out[0] = a[0] * factor1 + b[0] * factor2 + c[0] * factor3 + d[0] * factor4;
  out[1] = a[1] * factor1 + b[1] * factor2 + c[1] * factor3 + d[1] * factor4;
  out[2] = a[2] * factor1 + b[2] * factor2 + c[2] * factor3 + d[2] * factor4;
  return out;
}
/**
 * Generates a random vector with the given scale
 *
 * @param {vec3} out the receiving vector
 * @param {Number} [scale] Length of the resulting vector. If ommitted, a unit vector will be returned
 * @returns {vec3} out
 */


function random(out, scale) {
  scale = scale || 1.0;
  var r = glMatrix.RANDOM() * 2.0 * Math.PI;
  var z = glMatrix.RANDOM() * 2.0 - 1.0;
  var zScale = Math.sqrt(1.0 - z * z) * scale;
  out[0] = Math.cos(r) * zScale;
  out[1] = Math.sin(r) * zScale;
  out[2] = z * scale;
  return out;
}
/**
 * Transforms the vec3 with a mat4.
 * 4th vector component is implicitly '1'
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the vector to transform
 * @param {mat4} m matrix to transform with
 * @returns {vec3} out
 */


function transformMat4(out, a, m) {
  var x = a[0],
      y = a[1],
      z = a[2];
  var w = m[3] * x + m[7] * y + m[11] * z + m[15];
  w = w || 1.0;
  out[0] = (m[0] * x + m[4] * y + m[8] * z + m[12]) / w;
  out[1] = (m[1] * x + m[5] * y + m[9] * z + m[13]) / w;
  out[2] = (m[2] * x + m[6] * y + m[10] * z + m[14]) / w;
  return out;
}
/**
 * Transforms the vec3 with a mat3.
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the vector to transform
 * @param {mat3} m the 3x3 matrix to transform with
 * @returns {vec3} out
 */


function transformMat3(out, a, m) {
  var x = a[0],
      y = a[1],
      z = a[2];
  out[0] = x * m[0] + y * m[3] + z * m[6];
  out[1] = x * m[1] + y * m[4] + z * m[7];
  out[2] = x * m[2] + y * m[5] + z * m[8];
  return out;
}
/**
 * Transforms the vec3 with a quat
 * Can also be used for dual quaternions. (Multiply it with the real part)
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the vector to transform
 * @param {quat} q quaternion to transform with
 * @returns {vec3} out
 */


function transformQuat(out, a, q) {
  // benchmarks: https://jsperf.com/quaternion-transform-vec3-implementations-fixed
  var qx = q[0],
      qy = q[1],
      qz = q[2],
      qw = q[3];
  var x = a[0],
      y = a[1],
      z = a[2]; // var qvec = [qx, qy, qz];
  // var uv = vec3.cross([], qvec, a);

  var uvx = qy * z - qz * y,
      uvy = qz * x - qx * z,
      uvz = qx * y - qy * x; // var uuv = vec3.cross([], qvec, uv);

  var uuvx = qy * uvz - qz * uvy,
      uuvy = qz * uvx - qx * uvz,
      uuvz = qx * uvy - qy * uvx; // vec3.scale(uv, uv, 2 * w);

  var w2 = qw * 2;
  uvx *= w2;
  uvy *= w2;
  uvz *= w2; // vec3.scale(uuv, uuv, 2);

  uuvx *= 2;
  uuvy *= 2;
  uuvz *= 2; // return vec3.add(out, a, vec3.add(out, uv, uuv));

  out[0] = x + uvx + uuvx;
  out[1] = y + uvy + uuvy;
  out[2] = z + uvz + uuvz;
  return out;
}
/**
 * Rotate a 3D vector around the x-axis
 * @param {vec3} out The receiving vec3
 * @param {vec3} a The vec3 point to rotate
 * @param {vec3} b The origin of the rotation
 * @param {Number} rad The angle of rotation in radians
 * @returns {vec3} out
 */


function rotateX(out, a, b, rad) {
  var p = [],
      r = []; //Translate point to the origin

  p[0] = a[0] - b[0];
  p[1] = a[1] - b[1];
  p[2] = a[2] - b[2]; //perform rotation

  r[0] = p[0];
  r[1] = p[1] * Math.cos(rad) - p[2] * Math.sin(rad);
  r[2] = p[1] * Math.sin(rad) + p[2] * Math.cos(rad); //translate to correct position

  out[0] = r[0] + b[0];
  out[1] = r[1] + b[1];
  out[2] = r[2] + b[2];
  return out;
}
/**
 * Rotate a 3D vector around the y-axis
 * @param {vec3} out The receiving vec3
 * @param {vec3} a The vec3 point to rotate
 * @param {vec3} b The origin of the rotation
 * @param {Number} rad The angle of rotation in radians
 * @returns {vec3} out
 */


function rotateY(out, a, b, rad) {
  var p = [],
      r = []; //Translate point to the origin

  p[0] = a[0] - b[0];
  p[1] = a[1] - b[1];
  p[2] = a[2] - b[2]; //perform rotation

  r[0] = p[2] * Math.sin(rad) + p[0] * Math.cos(rad);
  r[1] = p[1];
  r[2] = p[2] * Math.cos(rad) - p[0] * Math.sin(rad); //translate to correct position

  out[0] = r[0] + b[0];
  out[1] = r[1] + b[1];
  out[2] = r[2] + b[2];
  return out;
}
/**
 * Rotate a 3D vector around the z-axis
 * @param {vec3} out The receiving vec3
 * @param {vec3} a The vec3 point to rotate
 * @param {vec3} b The origin of the rotation
 * @param {Number} rad The angle of rotation in radians
 * @returns {vec3} out
 */


function rotateZ(out, a, b, rad) {
  var p = [],
      r = []; //Translate point to the origin

  p[0] = a[0] - b[0];
  p[1] = a[1] - b[1];
  p[2] = a[2] - b[2]; //perform rotation

  r[0] = p[0] * Math.cos(rad) - p[1] * Math.sin(rad);
  r[1] = p[0] * Math.sin(rad) + p[1] * Math.cos(rad);
  r[2] = p[2]; //translate to correct position

  out[0] = r[0] + b[0];
  out[1] = r[1] + b[1];
  out[2] = r[2] + b[2];
  return out;
}
/**
 * Get the angle between two 3D vectors
 * @param {vec3} a The first operand
 * @param {vec3} b The second operand
 * @returns {Number} The angle in radians
 */


function angle(a, b) {
  var ax = a[0],
      ay = a[1],
      az = a[2],
      bx = b[0],
      by = b[1],
      bz = b[2],
      mag1 = Math.sqrt(ax * ax + ay * ay + az * az),
      mag2 = Math.sqrt(bx * bx + by * by + bz * bz),
      mag = mag1 * mag2,
      cosine = mag && dot(a, b) / mag;
  return Math.acos(Math.min(Math.max(cosine, -1), 1));
}
/**
 * Set the components of a vec3 to zero
 *
 * @param {vec3} out the receiving vector
 * @returns {vec3} out
 */


function zero(out) {
  out[0] = 0.0;
  out[1] = 0.0;
  out[2] = 0.0;
  return out;
}
/**
 * Returns a string representation of a vector
 *
 * @param {vec3} a vector to represent as a string
 * @returns {String} string representation of the vector
 */


function str(a) {
  return "vec3(" + a[0] + ", " + a[1] + ", " + a[2] + ")";
}
/**
 * Returns whether or not the vectors have exactly the same elements in the same position (when compared with ===)
 *
 * @param {vec3} a The first vector.
 * @param {vec3} b The second vector.
 * @returns {Boolean} True if the vectors are equal, false otherwise.
 */


function exactEquals(a, b) {
  return a[0] === b[0] && a[1] === b[1] && a[2] === b[2];
}
/**
 * Returns whether or not the vectors have approximately the same elements in the same position.
 *
 * @param {vec3} a The first vector.
 * @param {vec3} b The second vector.
 * @returns {Boolean} True if the vectors are equal, false otherwise.
 */


function equals(a, b) {
  var a0 = a[0],
      a1 = a[1],
      a2 = a[2];
  var b0 = b[0],
      b1 = b[1],
      b2 = b[2];
  return Math.abs(a0 - b0) <= glMatrix.EPSILON * Math.max(1.0, Math.abs(a0), Math.abs(b0)) && Math.abs(a1 - b1) <= glMatrix.EPSILON * Math.max(1.0, Math.abs(a1), Math.abs(b1)) && Math.abs(a2 - b2) <= glMatrix.EPSILON * Math.max(1.0, Math.abs(a2), Math.abs(b2));
}
/**
 * Alias for {@link vec3.subtract}
 * @function
 */


var sub = subtract;
/**
 * Alias for {@link vec3.multiply}
 * @function
 */

exports.sub = sub;
var mul = multiply;
/**
 * Alias for {@link vec3.divide}
 * @function
 */

exports.mul = mul;
var div = divide;
/**
 * Alias for {@link vec3.distance}
 * @function
 */

exports.div = div;
var dist = distance;
/**
 * Alias for {@link vec3.squaredDistance}
 * @function
 */

exports.dist = dist;
var sqrDist = squaredDistance;
/**
 * Alias for {@link vec3.length}
 * @function
 */

exports.sqrDist = sqrDist;
var len = length;
/**
 * Alias for {@link vec3.squaredLength}
 * @function
 */

exports.len = len;
var sqrLen = squaredLength;
/**
 * Perform some operation over an array of vec3s.
 *
 * @param {Array} a the array of vectors to iterate over
 * @param {Number} stride Number of elements between the start of each vec3. If 0 assumes tightly packed
 * @param {Number} offset Number of elements to skip at the beginning of the array
 * @param {Number} count Number of vec3s to iterate over. If 0 iterates over entire array
 * @param {Function} fn Function to call for each vector in the array
 * @param {Object} [arg] additional argument to pass to fn
 * @returns {Array} a
 * @function
 */

exports.sqrLen = sqrLen;

var forEach = function () {
  var vec = create();
  return function (a, stride, offset, count, fn, arg) {
    var i, l;

    if (!stride) {
      stride = 3;
    }

    if (!offset) {
      offset = 0;
    }

    if (count) {
      l = Math.min(count * stride + offset, a.length);
    } else {
      l = a.length;
    }

    for (i = offset; i < l; i += stride) {
      vec[0] = a[i];
      vec[1] = a[i + 1];
      vec[2] = a[i + 2];
      fn(vec, vec, arg);
      a[i] = vec[0];
      a[i + 1] = vec[1];
      a[i + 2] = vec[2];
    }

    return a;
  };
}();

exports.forEach = forEach;