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vector.js

Provides a simple 3D vector class. Vector operations can be done using member functions, which return new vectors, or static functions, which reuse existing vectors to avoid generating garbage.

 
function Vector(x, y, z) {
  this.x = x || 0;
  this.y = y || 0;
  this.z = z || 0;
}

Instance Methods

The methods add(), subtract(), multiply(), and divide() can all take either a vector or a number as an argument.

 
Vector.prototype = {
  negative: function() {
    return new Vector(-this.x, -this.y, -this.z);
  },
  add: function(v) {
    if (v instanceof Vector) return new Vector(this.x + v.x, this.y + v.y, this.z + v.z);
    else return new Vector(this.x + v, this.y + v, this.z + v);
  },
  subtract: function(v) {
    if (v instanceof Vector) return new Vector(this.x - v.x, this.y - v.y, this.z - v.z);
    else return new Vector(this.x - v, this.y - v, this.z - v);
  },
  multiply: function(v) {
    if (v instanceof Vector) return new Vector(this.x * v.x, this.y * v.y, this.z * v.z);
    else return new Vector(this.x * v, this.y * v, this.z * v);
  },
  divide: function(v) {
    if (v instanceof Vector) return new Vector(this.x / v.x, this.y / v.y, this.z / v.z);
    else return new Vector(this.x / v, this.y / v, this.z / v);
  },
  equals: function(v) {
    return this.x == v.x && this.y == v.y && this.z == v.z;
  },
  dot: function(v) {
    return this.x * v.x + this.y * v.y + this.z * v.z;
  },
  cross: function(v) {
    return new Vector(
      this.y * v.z - this.z * v.y,
      this.z * v.x - this.x * v.z,
      this.x * v.y - this.y * v.x
    );
  },
  length: function() {
    return Math.sqrt(this.dot(this));
  },
  unit: function() {
    return this.divide(this.length());
  },
  min: function() {
    return Math.min(Math.min(this.x, this.y), this.z);
  },
  max: function() {
    return Math.max(Math.max(this.x, this.y), this.z);
  },
  toAngles: function() {
    return {
      theta: Math.atan2(this.z, this.x),
      phi: Math.asin(this.y / this.length())
    };
  },
  angleTo: function(a) {
    return Math.acos(this.dot(a) / (this.length() * a.length()));
  },
  toArray: function(n) {
    return [this.x, this.y, this.z].slice(0, n || 3);
  },
  clone: function() {
    return new Vector(this.x, this.y, this.z);
  },
  init: function(x, y, z) {
    this.x = x; this.y = y; this.z = z;
    return this;
  }
};

Static Methods

Vector.randomDirection() returns a vector with a length of 1 and a statistically uniform direction. Vector.lerp() performs linear interpolation between two vectors.

 
Vector.negative = function(a, b) {
  b.x = -a.x; b.y = -a.y; b.z = -a.z;
  return b;
};
Vector.add = function(a, b, c) {
  if (b instanceof Vector) { c.x = a.x + b.x; c.y = a.y + b.y; c.z = a.z + b.z; }
  else { c.x = a.x + b; c.y = a.y + b; c.z = a.z + b; }
  return c;
};
Vector.subtract = function(a, b, c) {
  if (b instanceof Vector) { c.x = a.x - b.x; c.y = a.y - b.y; c.z = a.z - b.z; }
  else { c.x = a.x - b; c.y = a.y - b; c.z = a.z - b; }
  return c;
};
Vector.multiply = function(a, b, c) {
  if (b instanceof Vector) { c.x = a.x * b.x; c.y = a.y * b.y; c.z = a.z * b.z; }
  else { c.x = a.x * b; c.y = a.y * b; c.z = a.z * b; }
  return c;
};
Vector.divide = function(a, b, c) {
  if (b instanceof Vector) { c.x = a.x / b.x; c.y = a.y / b.y; c.z = a.z / b.z; }
  else { c.x = a.x / b; c.y = a.y / b; c.z = a.z / b; }
  return c;
};
Vector.cross = function(a, b, c) {
  c.x = a.y * b.z - a.z * b.y;
  c.y = a.z * b.x - a.x * b.z;
  c.z = a.x * b.y - a.y * b.x;
  return c;
};
Vector.unit = function(a, b) {
  var length = a.length();
  b.x = a.x / length;
  b.y = a.y / length;
  b.z = a.z / length;
  return b;
};
Vector.fromAngles = function(theta, phi) {
  return new Vector(Math.cos(theta) * Math.cos(phi), Math.sin(phi), Math.sin(theta) * Math.cos(phi));
};
Vector.randomDirection = function() {
  return Vector.fromAngles(Math.random() * Math.PI * 2, Math.asin(Math.random() * 2 - 1));
};
Vector.min = function(a, b) {
  return new Vector(Math.min(a.x, b.x), Math.min(a.y, b.y), Math.min(a.z, b.z));
};
Vector.max = function(a, b) {
  return new Vector(Math.max(a.x, b.x), Math.max(a.y, b.y), Math.max(a.z, b.z));
};
Vector.lerp = function(a, b, fraction) {
  return b.subtract(a).multiply(fraction).add(a);
};
Vector.fromArray = function(a) {
  return new Vector(a[0], a[1], a[2]);
};
Vector.angleBetween = function(a, b) {
  return a.angleTo(b);
};