@egjs/view360/src/utils/mathUtil/vec3.js

360 integrated viewing solution from inside-out view to outside-in view. It provides user-friendly service by rotating 360 degrees through various user interaction such as motion sensor and touch.

/**
 * Original Code
 * https://github.com/toji/gl-matrix/blob/v2.3.2/src/gl-matrix/vec3.js
 * 3 Dimensional Vector Util
 * modified by egjs
 */
import glMatrix from "./common.js";

/**
 * @class 3 Dimensional Vector
 * @name vec3
 */
var vec3 = {};

/**
 * Creates a new, empty vec3
 *
 * @returns {vec3} a new 3D vector
 */
vec3.create = function() {
    var out = new glMatrix.ARRAY_TYPE(3);
    out[0] = 0;
    out[1] = 0;
    out[2] = 0;
    return out;
};

/**
 * 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
 */
vec3.fromValues = function(x, y, z) {
    var out = new glMatrix.ARRAY_TYPE(3);
    out[0] = x;
    out[1] = y;
    out[2] = z;
    return out;
};

vec3.set = function(out, x, y, z) {
    out[0] = x;
    out[1] = y;
    out[2] = z;
    return out;
};

vec3.copy = function(out, a) {
    out[0] = a[0];
    out[1] = a[1];
    out[2] = 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
 */
vec3.scale = function(out, a, b) {
    out[0] = a[0] * b;
    out[1] = a[1] * b;
    out[2] = a[2] * b;
    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
 */
vec3.subtract = function(out, a, b) {
    out[0] = a[0] - b[0];
    out[1] = a[1] - b[1];
    out[2] = a[2] - b[2];
    return out;
};

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

/**
 * Normalize a vec3
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a vector to normalize
 * @returns {vec3} out
 */
vec3.normalize = function(out, a) {
    var x = a[0],
        y = a[1],
        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
 */
vec3.dot = function (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
 */
vec3.cross = function(out, a, b) {
    var ax = a[0], ay = a[1], az = a[2],
        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;
};

/**
 * Transforms the vec3 with a quat
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the vector to transform
 * @param {quat} q quaternion to transform with
 * @returns {vec3} out
 */
vec3.transformQuat = function(out, a, q) {
    // benchmarks: http://jsperf.com/quaternion-transform-vec3-implementations

    var x = a[0], y = a[1], z = a[2],
        qx = q[0], qy = q[1], qz = q[2], qw = q[3],

        // calculate quat * vec
        ix = qw * x + qy * z - qz * y,
        iy = qw * y + qz * x - qx * z,
        iz = qw * z + qx * y - qy * x,
        iw = -qx * x - qy * y - qz * z;

    // calculate result * inverse quat
    out[0] = ix * qw + iw * -qx + iy * -qz - iz * -qy;
    out[1] = iy * qw + iw * -qy + iz * -qx - ix * -qz;
    out[2] = iz * qw + iw * -qz + ix * -qy - iy * -qx;
    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} c The angle of rotation
 * @returns {vec3} out
 */
vec3.rotateZ = function(out, a, b, c){
	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(c) - p[1]*Math.sin(c);
	r[1] = p[0]*Math.sin(c) + p[1]*Math.cos(c);
	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;
};

export default vec3;