@egjs/view360/src/utils/mathUtil/quat.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/quat.js
 * Quaternion util
 * modified by egjs
 */
import glMatrix from "./common.js";

/**
 * @class Quaternion
 * @name quat
 */
var quat = {};

/**
 * Creates a new identity quat
 *
 * @returns {quat} a new quaternion
 */
quat.create = function() {
    var out = new glMatrix.ARRAY_TYPE(4);
    out[0] = 0;
    out[1] = 0;
    out[2] = 0;
    out[3] = 1;
    return out;
};

/**
 * Creates a new quat initialized with values from an existing quaternion
 *
 * @param {quat} a quaternion to clone
 * @returns {quat} a new quaternion
 * @function
 */
quat.clone = function(a) {
    var out = new glMatrix.ARRAY_TYPE(4);
    out[0] = a[0];
    out[1] = a[1];
    out[2] = a[2];
    out[3] = a[3];
    return out;
};

/**
 * Creates a new quat initialized with the given values
 *
 * @param {Number} x X component
 * @param {Number} y Y component
 * @param {Number} z Z component
 * @param {Number} w W component
 * @returns {quat} a new quaternion
 * @function
 */
quat.fromValues = function(x, y, z, w) {
    var out = new glMatrix.ARRAY_TYPE(4);
    out[0] = x;
    out[1] = y;
    out[2] = z;
    out[3] = w;
    return out;
};;

/**
 * Copy the values from one quat to another
 *
 * @param {quat} out the receiving quaternion
 * @param {quat} a the source quaternion
 * @returns {quat} out
 * @function
 */
quat.copy = function(out, a) {
    out[0] = a[0];
    out[1] = a[1];
    out[2] = a[2];
    out[3] = a[3];
    return out;
};

/**
 * Sets a quat from the given angle and rotation axis,
 * then returns it.
 *
 * @param {quat} out the receiving quaternion
 * @param {vec3} axis the axis around which to rotate
 * @param {Number} rad the angle in radians
 * @returns {quat} out
 **/
quat.setAxisAngle = function(out, axis, rad) {
    rad = rad * 0.5;
    var s = Math.sin(rad);
    out[0] = s * axis[0];
    out[1] = s * axis[1];
    out[2] = s * axis[2];
    out[3] = Math.cos(rad);
    return out;
};

/**
 * Multiplies two quat's
 *
 * @param {quat} out the receiving quaternion
 * @param {quat} a the first operand
 * @param {quat} b the second operand
 * @returns {quat} out
 */
quat.multiply = function(out, a, b) {
    var ax = a[0], ay = a[1], az = a[2], aw = a[3],
        bx = b[0], by = b[1], bz = b[2], bw = b[3];

    out[0] = ax * bw + aw * bx + ay * bz - az * by;
    out[1] = ay * bw + aw * by + az * bx - ax * bz;
    out[2] = az * bw + aw * bz + ax * by - ay * bx;
    out[3] = aw * bw - ax * bx - ay * by - az * bz;
    return out;
};

/**
 * Rotates a quaternion by the given angle about the X axis
 *
 * @param {quat} out quat receiving operation result
 * @param {quat} a quat to rotate
 * @param {number} rad angle (in radians) to rotate
 * @returns {quat} out
 */
quat.rotateX = function (out, a, rad) {
    rad *= 0.5;

    var ax = a[0], ay = a[1], az = a[2], aw = a[3],
        bx = Math.sin(rad), bw = Math.cos(rad);

    out[0] = ax * bw + aw * bx;
    out[1] = ay * bw + az * bx;
    out[2] = az * bw - ay * bx;
    out[3] = aw * bw - ax * bx;
    return out;
};

/**
 * Rotates a quaternion by the given angle about the Y axis
 *
 * @param {quat} out quat receiving operation result
 * @param {quat} a quat to rotate
 * @param {number} rad angle (in radians) to rotate
 * @returns {quat} out
 */
quat.rotateY = function (out, a, rad) {
    rad *= 0.5;

    var ax = a[0], ay = a[1], az = a[2], aw = a[3],
        by = Math.sin(rad), bw = Math.cos(rad);

    out[0] = ax * bw - az * by;
    out[1] = ay * bw + aw * by;
    out[2] = az * bw + ax * by;
    out[3] = aw * bw - ay * by;
    return out;
};

/**
 * Calculates the conjugate of a quat
 * If the quaternion is normalized, this function is faster than quat.inverse and produces the same result.
 *
 * @param {quat} out the receiving quaternion
 * @param {quat} a quat to calculate conjugate of
 * @returns {quat} out
 */
quat.conjugate = function (out, a) {
    out[0] = -a[0];
    out[1] = -a[1];
    out[2] = -a[2];
    out[3] = a[3];
    return out;
};

/**
 * Normalize a quat
 *
 * @param {quat} out the receiving quaternion
 * @param {quat} a quaternion to normalize
 * @returns {quat} out
 * @function
 */
quat.normalize = function(out, a) {
    var x = a[0],
        y = a[1],
        z = a[2],
        w = a[3];
    var len = x*x + y*y + z*z + w*w;
    if (len > 0) {
        len = 1 / Math.sqrt(len);
        out[0] = x * len;
        out[1] = y * len;
        out[2] = z * len;
        out[3] = w * len;
    }
    return out;
};

/**
 * Returns whether or not the quaternions have approximately the same elements in the same position (when compared with ===)
 *
 * @param {quat} a The first quaternion.
 * @param {quat} b The second quaternion.
 * @returns {Boolean} True if the vectors are equal, false otherwise.
 */
quat.equals = function (a, b) {
    let a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3];
    let b0 = b[0], b1 = b[1], b2 = b[2], b3 = b[3];
    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)) &&
            Math.abs(a3 - b3) <= glMatrix.EPSILON * Math.max(1.0, Math.abs(a3), Math.abs(b3)));
  }

/**
 * Returns whether or not the quaternions have exactly the same elements in the same position (when compared with ===)
 *
 * @param {quat} a The first quaternion.
 * @param {quat} b The second quaternion.
 * @returns {Boolean} True if the vectors are equal, false otherwise.
 */
quat.exactEquals = function (a, b) {
    return a[0] === b[0] && a[1] === b[1] && a[2] === b[2] && a[3] === b[3];
};

export default quat;