Source: math/vec3.js

Object.assign(pc, (function () {
    'use strict';

    /**
     * @constructor
     * @name pc.Vec3
     * @classdesc A 3-dimensional vector.
     * @description Creates a new Vec3 object.
     * @param {Number} [x] The x value. If x is an array of length 3, the array will be used to populate all components.
     * @param {Number} [y] The y value.
     * @param {Number} [z] The z value.
     * @example
     * var v = new pc.Vec3(1, 2, 3);
     */
    var Vec3 = function (x, y, z) {
        if (x && x.length === 3) {
            this.x = x[0];
            this.y = x[1];
            this.z = x[2];
        } else {
            this.x = x || 0;
            this.y = y || 0;
            this.z = z || 0;
        }
    };

    Object.assign(Vec3.prototype, {
        /**
         * @function
         * @name pc.Vec3#add
         * @description Adds a 3-dimensional vector to another in place.
         * @param {pc.Vec3} rhs The vector to add to the specified vector.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var a = new pc.Vec3(10, 10, 10);
         * var b = new pc.Vec3(20, 20, 20);
         *
         * a.add(b);
         *
         * // Should output [30, 30, 30]
         * console.log("The result of the addition is: " + a.toString());
         */
        add: function (rhs) {
            this.x += rhs.x;
            this.y += rhs.y;
            this.z += rhs.z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#add2
         * @description Adds two 3-dimensional vectors together and returns the result.
         * @param {pc.Vec3} lhs The first vector operand for the addition.
         * @param {pc.Vec3} rhs The second vector operand for the addition.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var a = new pc.Vec3(10, 10, 10);
         * var b = new pc.Vec3(20, 20, 20);
         * var r = new pc.Vec3();
         *
         * r.add2(a, b);
         * // Should output [30, 30, 30]
         *
         * console.log("The result of the addition is: " + r.toString());
         */
        add2: function (lhs, rhs) {
            this.x = lhs.x + rhs.x;
            this.y = lhs.y + rhs.y;
            this.z = lhs.z + rhs.z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#clone
         * @description Returns an identical copy of the specified 3-dimensional vector.
         * @returns {pc.Vec3} A 3-dimensional vector containing the result of the cloning.
         * @example
         * var v = new pc.Vec3(10, 20, 30);
         * var vclone = v.clone();
         * console.log("The result of the cloning is: " + vclone.toString());
         */
        clone: function () {
            return new Vec3().copy(this);
        },

        /**
         * @function
         * @name pc.Vec3#copy
         * @description Copied the contents of a source 3-dimensional vector to a destination 3-dimensional vector.
         * @param {pc.Vec3} rhs A vector to copy to the specified vector.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var src = new pc.Vec3(10, 20, 30);
         * var dst = new pc.Vec3();
         *
         * dst.copy(src);
         *
         * console.log("The two vectors are " + (dst.equals(src) ? "equal" : "different"));
         */
        copy: function (rhs) {
            this.x = rhs.x;
            this.y = rhs.y;
            this.z = rhs.z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#cross
         * @description Returns the result of a cross product operation performed on the two specified 3-dimensional vectors.
         * @param {pc.Vec3} lhs The first 3-dimensional vector operand of the cross product.
         * @param {pc.Vec3} rhs The second 3-dimensional vector operand of the cross product.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var back = new pc.Vec3().cross(pc.Vec3.RIGHT, pc.Vec3.UP);
         *
         * // Should print the Z axis (i.e. [0, 0, 1])
         * console.log("The result of the cross product is: " + back.toString());
         */
        cross: function (lhs, rhs) {
            // Create temporary variables in case lhs or rhs are 'this'
            var lx = lhs.x;
            var ly = lhs.y;
            var lz = lhs.z;
            var rx = rhs.x;
            var ry = rhs.y;
            var rz = rhs.z;

            this.x = ly * rz - ry * lz;
            this.y = lz * rx - rz * lx;
            this.z = lx * ry - rx * ly;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#dot
         * @description Returns the result of a dot product operation performed on the two specified 3-dimensional vectors.
         * @param {pc.Vec3} rhs The second 3-dimensional vector operand of the dot product.
         * @returns {Number} The result of the dot product operation.
         * @example
         * var v1 = new pc.Vec3(5, 10, 20);
         * var v2 = new pc.Vec3(10, 20, 40);
         * var v1dotv2 = v1.dot(v2);
         * console.log("The result of the dot product is: " + v1dotv2);
         */
        dot: function (rhs) {
            return this.x * rhs.x + this.y * rhs.y + this.z * rhs.z;
        },

        /**
         * @function
         * @name pc.Vec3#equals
         * @description Reports whether two vectors are equal.
         * @param {pc.Vec3} rhs The vector to compare to the specified vector.
         * @returns {Boolean} true if the vectors are equal and false otherwise.
         * @example
         * var a = new pc.Vec3(1, 2, 3);
         * var b = new pc.Vec3(4, 5, 6);
         * console.log("The two vectors are " + (a.equals(b) ? "equal" : "different"));
         */
        equals: function (rhs) {
            return this.x === rhs.x && this.y === rhs.y && this.z === rhs.z;
        },

        /**
         * @function
         * @name pc.Vec3#length
         * @description Returns the magnitude of the specified 3-dimensional vector.
         * @returns {Number} The magnitude of the specified 3-dimensional vector.
         * @example
         * var vec = new pc.Vec3(3, 4, 0);
         * var len = vec.length();
         * // Should output 5
         * console.log("The length of the vector is: " + len);
         */
        length: function () {
            return Math.sqrt(this.x * this.x + this.y * this.y + this.z * this.z);
        },

        /**
         * @function
         * @name pc.Vec3#lengthSq
         * @description Returns the magnitude squared of the specified 3-dimensional vector.
         * @returns {Number} The magnitude of the specified 3-dimensional vector.
         * @example
         * var vec = new pc.Vec3(3, 4, 0);
         * var len = vec.lengthSq();
         * // Should output 25
         * console.log("The length squared of the vector is: " + len);
         */
        lengthSq: function () {
            return this.x * this.x + this.y * this.y + this.z * this.z;
        },

        /**
         * @function
         * @name pc.Vec3#lerp
         * @description Returns the result of a linear interpolation between two specified 3-dimensional vectors.
         * @param {pc.Vec3} lhs The 3-dimensional to interpolate from.
         * @param {pc.Vec3} rhs The 3-dimensional to interpolate to.
         * @param {Number} alpha The value controlling the point of interpolation. Between 0 and 1, the linear interpolant
         * will occur on a straight line between lhs and rhs. Outside of this range, the linear interpolant will occur on
         * a ray extrapolated from this line.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var a = new pc.Vec3(0, 0, 0);
         * var b = new pc.Vec3(10, 10, 10);
         * var r = new pc.Vec3();
         *
         * r.lerp(a, b, 0);   // r is equal to a
         * r.lerp(a, b, 0.5); // r is 5, 5, 5
         * r.lerp(a, b, 1);   // r is equal to b
         */
        lerp: function (lhs, rhs, alpha) {
            this.x = lhs.x + alpha * (rhs.x - lhs.x);
            this.y = lhs.y + alpha * (rhs.y - lhs.y);
            this.z = lhs.z + alpha * (rhs.z - lhs.z);

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#mul
         * @description Multiplies a 3-dimensional vector to another in place.
         * @param {pc.Vec3} rhs The 3-dimensional vector used as the second multiplicand of the operation.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var a = new pc.Vec3(2, 3, 4);
         * var b = new pc.Vec3(4, 5, 6);
         *
         * a.mul(b);
         *
         * // Should output 8, 15, 24
         * console.log("The result of the multiplication is: " + a.toString());
         */
        mul: function (rhs) {
            this.x *= rhs.x;
            this.y *= rhs.y;
            this.z *= rhs.z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#mul2
         * @description Returns the result of multiplying the specified 3-dimensional vectors together.
         * @param {pc.Vec3} lhs The 3-dimensional vector used as the first multiplicand of the operation.
         * @param {pc.Vec3} rhs The 3-dimensional vector used as the second multiplicand of the operation.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var a = new pc.Vec3(2, 3, 4);
         * var b = new pc.Vec3(4, 5, 6);
         * var r = new pc.Vec3();
         *
         * r.mul2(a, b);
         *
         * // Should output 8, 15, 24
         * console.log("The result of the multiplication is: " + r.toString());
         */
        mul2: function (lhs, rhs) {
            this.x = lhs.x * rhs.x;
            this.y = lhs.y * rhs.y;
            this.z = lhs.z * rhs.z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#normalize
         * @description Returns the specified 3-dimensional vector copied and converted to a unit vector.
         * If the vector has a length of zero, the vector's elements will be set to zero.
         * @returns {pc.Vec3} The result of the normalization.
         * @example
         * var v = new pc.Vec3(25, 0, 0);
         *
         * v.normalize();
         *
         * // Should output 1, 0, 0, 0
         * console.log("The result of the vector normalization is: " + v.toString());
         */
        normalize: function () {
            var lengthSq = this.x * this.x + this.y * this.y + this.z * this.z;
            if (lengthSq > 0) {
                var invLength = 1 / Math.sqrt(lengthSq);
                this.x *= invLength;
                this.y *= invLength;
                this.z *= invLength;
            }

            return this;
        },

        /**
         * @function
         * @name  pc.Vec3#project
         * @description Projects this 3-dimensional vector onto the specified vector.
         * @param {pc.Vec3} rhs The vector onto which the original vector will be projected on.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var v = new pc.Vec3(5, 5, 5);
         * var normal = new pc.Vec3(1, 0, 0);
         *
         * v.project(normal);
         *
         * // Should output 5, 0, 0
         * console.log("The result of the vector projection is: " + v.toString());
         */
        project: function (rhs) {
            var a_dot_b = this.x * rhs.x + this.y * rhs.y + this.z * rhs.z;
            var b_dot_b = rhs.x * rhs.x + rhs.y * rhs.y + rhs.z * rhs.z;
            var s = a_dot_b / b_dot_b;
            this.x = rhs.x * s;
            this.y = rhs.y * s;
            this.z = rhs.z * s;
            return this;
        },

        /**
         * @function
         * @name pc.Vec3#scale
         * @description Scales each dimension of the specified 3-dimensional vector by the supplied
         * scalar value.
         * @param {Number} scalar The value by which each vector component is multiplied.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var v = new pc.Vec3(2, 4, 8);
         *
         * // Multiply by 2
         * v.scale(2);
         *
         * // Negate
         * v.scale(-1);
         *
         * // Divide by 2
         * v.scale(0.5);
         */
        scale: function (scalar) {
            this.x *= scalar;
            this.y *= scalar;
            this.z *= scalar;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#set
         * @description Sets the specified 3-dimensional vector to the supplied numerical values.
         * @param {Number} x The value to set on the first component of the vector.
         * @param {Number} y The value to set on the second component of the vector.
         * @param {Number} z The value to set on the third component of the vector.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var v = new pc.Vec3();
         * v.set(5, 10, 20);
         *
         * // Should output 5, 10, 20
         * console.log("The result of the vector set is: " + v.toString());
         */
        set: function (x, y, z) {
            this.x = x;
            this.y = y;
            this.z = z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#sub
         * @description Subtracts a 3-dimensional vector from another in place.
         * @param {pc.Vec3} rhs The vector to add to the specified vector.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var a = new pc.Vec3(10, 10, 10);
         * var b = new pc.Vec3(20, 20, 20);
         *
         * a.sub(b);
         *
         * // Should output [-10, -10, -10]
         * console.log("The result of the addition is: " + a.toString());
         */
        sub: function (rhs) {
            this.x -= rhs.x;
            this.y -= rhs.y;
            this.z -= rhs.z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#sub2
         * @description Subtracts two 3-dimensional vectors from one another and returns the result.
         * @param {pc.Vec3} lhs The first vector operand for the addition.
         * @param {pc.Vec3} rhs The second vector operand for the addition.
         * @returns {pc.Vec3} Self for chaining.
         * @example
         * var a = new pc.Vec3(10, 10, 10);
         * var b = new pc.Vec3(20, 20, 20);
         * var r = new pc.Vec3();
         *
         * r.sub2(a, b);
         *
         * // Should output [-10, -10, -10]
         * console.log("The result of the addition is: " + r.toString());
         */
        sub2: function (lhs, rhs) {
            this.x = lhs.x - rhs.x;
            this.y = lhs.y - rhs.y;
            this.z = lhs.z - rhs.z;

            return this;
        },

        /**
         * @function
         * @name pc.Vec3#toString
         * @description Converts the vector to string form.
         * @returns {String} The vector in string form.
         * @example
         * var v = new pc.Vec3(20, 10, 5);
         * // Should output '[20, 10, 5]'
         * console.log(v.toString());
         */
        toString: function () {
            return '[' + this.x + ', ' + this.y + ', ' + this.z + ']';
        }
    });

    /**
     * @name pc.Vec3#x
     * @type Number
     * @description The first component of the vector.
     * @example
     * var vec = new pc.Vec3(10, 20, 30);
     *
     * // Get x
     * var x = vec.x;
     *
     * // Set x
     * vec.x = 0;
     */
    /**
     * @name pc.Vec3#y
     * @type Number
     * @description The second component of the vector.
     * @example
     * var vec = new pc.Vec3(10, 20, 30);
     *
     * // Get y
     * var y = vec.y;
     *
     * // Set y
     * vec.y = 0;
     */
    /**
     * @name pc.Vec3#z
     * @type Number
     * @description The third component of the vector.
     * @example
     * var vec = new pc.Vec3(10, 20, 30);
     *
     * // Get z
     * var z = vec.z;
     *
     * // Set z
     * vec.z = 0;
     */

    /**
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.BACK
     * @description A constant vector set to [0, 0, 1].
     */
    Object.defineProperty(Vec3, 'BACK', {
        get: (function () {
            var back = new Vec3(0, 0, 1);
            return function () {
                return back;
            };
        }())
    });

    /**
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.DOWN
     * @description A constant vector set to [0, -1, 0].
     */
    Object.defineProperty(Vec3, 'DOWN', {
        get: (function () {
            var down = new Vec3(0, -1, 0);
            return function () {
                return down;
            };
        }())
    });

    /**
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.FORWARD
     * @description A constant vector set to [0, 0, -1].
     */
    Object.defineProperty(Vec3, 'FORWARD', {
        get: (function () {
            var forward = new Vec3(0, 0, -1);
            return function () {
                return forward;
            };
        }())
    });

    /**
     * @field
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.LEFT
     * @description A constant vector set to [-1, 0, 0].
     */
    Object.defineProperty(Vec3, 'LEFT', {
        get: (function () {
            var left = new Vec3(-1, 0, 0);
            return function () {
                return left;
            };
        }())
    });

    /**
     * @field
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.ONE
     * @description A constant vector set to [1, 1, 1].
     */
    Object.defineProperty(Vec3, 'ONE', {
        get: (function () {
            var one = new Vec3(1, 1, 1);
            return function () {
                return one;
            };
        }())
    });

    /**
     * @field
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.RIGHT
     * @description A constant vector set to [1, 0, 0].
     */
    Object.defineProperty(Vec3, 'RIGHT', {
        get: (function () {
            var right = new Vec3(1, 0, 0);
            return function () {
                return right;
            };
        }())
    });

    /**
     * @field
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.UP
     * @description A constant vector set to [0, 1, 0].
     */
    Object.defineProperty(Vec3, 'UP', {
        get: (function () {
            var down = new Vec3(0, 1, 0);
            return function () {
                return down;
            };
        }())
    });

    /**
     * @field
     * @static
     * @readonly
     * @type pc.Vec3
     * @name pc.Vec3.ZERO
     * @description A constant vector set to [0, 0, 0].
     */
    Object.defineProperty(Vec3, 'ZERO', {
        get: (function () {
            var zero = new Vec3(0, 0, 0);
            return function () {
                return zero;
            };
        }())
    });

    return {
        Vec3: Vec3
    };
}()));