/**
 * A quaternion.
 *
 * @category Math
 */
export class Quat {
    /**
     * A constant quaternion set to [0, 0, 0, 1] (the identity).
     *
     * @type {Quat}
     * @readonly
     */
    static readonly IDENTITY: Quat;
    /**
     * A constant quaternion set to [0, 0, 0, 0].
     *
     * @type {Quat}
     * @readonly
     */
    static readonly ZERO: Quat;
    /**
     * Create a new Quat instance.
     *
     * @param {number|number[]} [x] - The quaternion's x component. Defaults to 0. If x is an array
     * of length 4, the array will be used to populate all components.
     * @param {number} [y] - The quaternion's y component. Defaults to 0.
     * @param {number} [z] - The quaternion's z component. Defaults to 0.
     * @param {number} [w] - The quaternion's w component. Defaults to 1.
     */
    constructor(x?: number | number[], y?: number, z?: number, w?: number);
    /**
     * The x component of the quaternion.
     *
     * @type {number}
     */
    x: number;
    /**
     * The y component of the quaternion.
     *
     * @type {number}
     */
    y: number;
    /**
     * The z component of the quaternion.
     *
     * @type {number}
     */
    z: number;
    /**
     * The w component of the quaternion.
     *
     * @type {number}
     */
    w: number;
    /**
     * Returns an identical copy of the specified quaternion.
     *
     * @returns {this} A quaternion containing the result of the cloning.
     * @example
     * const q = new pc.Quat(-0.11, -0.15, -0.46, 0.87);
     * const qclone = q.clone();
     *
     * console.log("The result of the cloning is: " + q.toString());
     */
    clone(): this;
    conjugate(src?: this): this;
    /**
     * Copies the contents of a source quaternion to a destination quaternion.
     *
     * @param {Quat} rhs - The quaternion to be copied.
     * @returns {Quat} Self for chaining.
     * @example
     * const src = new pc.Quat();
     * const dst = new pc.Quat();
     * dst.copy(src, src);
     * console.log("The two quaternions are " + (src.equals(dst) ? "equal" : "different"));
     */
    copy(rhs: Quat): Quat;
    /**
     * Reports whether two quaternions are equal.
     *
     * @param {Quat} rhs - The quaternion to be compared against.
     * @returns {boolean} True if the quaternions are equal and false otherwise.
     * @example
     * const a = new pc.Quat();
     * const b = new pc.Quat();
     * console.log("The two quaternions are " + (a.equals(b) ? "equal" : "different"));
     */
    equals(rhs: Quat): boolean;
    /**
     * Reports whether two quaternions are equal using an absolute error tolerance.
     *
     * @param {Quat} rhs - The quaternion to be compared against.
     * @param {number} [epsilon] - The maximum difference between each component of the two
     * quaternions. Defaults to 1e-6.
     * @returns {boolean} True if the quaternions are equal and false otherwise.
     * @example
     * const a = new pc.Quat();
     * const b = new pc.Quat();
     * console.log("The two quaternions are approximately " + (a.equalsApprox(b, 1e-9) ? "equal" : "different"));
     */
    equalsApprox(rhs: Quat, epsilon?: number): boolean;
    /**
     * Gets the rotation axis and angle for a given quaternion. If a quaternion is created with
     * `setFromAxisAngle`, this method will return the same values as provided in the original
     * parameter list OR functionally equivalent values.
     *
     * @param {Vec3} axis - The 3-dimensional vector to receive the axis of rotation.
     * @returns {number} Angle, in degrees, of the rotation.
     * @example
     * const q = new pc.Quat();
     * q.setFromAxisAngle(new pc.Vec3(0, 1, 0), 90);
     * const v = new pc.Vec3();
     * const angle = q.getAxisAngle(v);
     * // Outputs 90
     * console.log(angle);
     * // Outputs [0, 1, 0]
     * console.log(v.toString());
     */
    getAxisAngle(axis: Vec3): number;
    /**
     * Converts the supplied quaternion to Euler angles.
     *
     * @param {Vec3} [eulers] - The 3-dimensional vector to receive the Euler angles.
     * @returns {Vec3} The 3-dimensional vector holding the Euler angles that
     * correspond to the supplied quaternion.
     */
    getEulerAngles(eulers?: Vec3): Vec3;
    /**
     * Generates the inverse of the specified quaternion.
     *
     * @param {Quat} [src] - The quaternion to invert. If not set, the operation is done in place.
     * @returns {Quat} Self for chaining.
     * @example
     * // Create a quaternion rotated 180 degrees around the y-axis
     * const rot = new pc.Quat().setFromEulerAngles(0, 180, 0);
     *
     * // Invert in place
     * rot.invert();
     */
    invert(src?: Quat): Quat;
    /**
     * Returns the magnitude of the specified quaternion.
     *
     * @returns {number} The magnitude of the specified quaternion.
     * @example
     * const q = new pc.Quat(0, 0, 0, 5);
     * const len = q.length();
     * // Outputs 5
     * console.log("The length of the quaternion is: " + len);
     */
    length(): number;
    /**
     * Returns the magnitude squared of the specified quaternion.
     *
     * @returns {number} The magnitude of the specified quaternion.
     * @example
     * const q = new pc.Quat(3, 4, 0);
     * const lenSq = q.lengthSq();
     * // Outputs 25
     * console.log("The length squared of the quaternion is: " + lenSq);
     */
    lengthSq(): number;
    /**
     * Returns the result of multiplying the specified quaternions together.
     *
     * @param {Quat} rhs - The quaternion used as the second multiplicand of the operation.
     * @returns {Quat} Self for chaining.
     * @example
     * const a = new pc.Quat().setFromEulerAngles(0, 30, 0);
     * const b = new pc.Quat().setFromEulerAngles(0, 60, 0);
     *
     * // a becomes a 90 degree rotation around the Y axis
     * // In other words, a = a * b
     * a.mul(b);
     *
     * console.log("The result of the multiplication is: " + a.toString());
     */
    mul(rhs: Quat): Quat;
    /**
     * Multiplies each element of a quaternion by a number.
     *
     * @param {number} scalar - The number to multiply by.
     * @param {Quat} [src] - The quaternion to scale. If not set, the operation is done in place.
     * @returns {Quat} Self for chaining.
     */
    mulScalar(scalar: number, src?: Quat): Quat;
    /**
     * Returns the result of multiplying the specified quaternions together.
     *
     * @param {Quat} lhs - The quaternion used as the first multiplicand of the operation.
     * @param {Quat} rhs - The quaternion used as the second multiplicand of the operation.
     * @returns {Quat} Self for chaining.
     * @example
     * const a = new pc.Quat().setFromEulerAngles(0, 30, 0);
     * const b = new pc.Quat().setFromEulerAngles(0, 60, 0);
     * const r = new pc.Quat();
     *
     * // r is set to a 90 degree rotation around the Y axis
     * // In other words, r = a * b
     * r.mul2(a, b);
     *
     * console.log("The result of the multiplication is: " + r.toString());
     */
    mul2(lhs: Quat, rhs: Quat): Quat;
    /**
     * Returns the specified quaternion converted in place to a unit quaternion.
     *
     * @param {Quat} [src] - The quaternion to normalize. If not set, the operation is done in place.
     * @returns {Quat} The result of the normalization.
     * @example
     * const v = new pc.Quat(0, 0, 0, 5);
     *
     * v.normalize();
     *
     * // Outputs 0, 0, 0, 1
     * console.log("The result of the vector normalization is: " + v.toString());
     */
    normalize(src?: Quat): Quat;
    /**
     * Sets the specified quaternion to the supplied numerical values.
     *
     * @param {number} x - The x component of the quaternion.
     * @param {number} y - The y component of the quaternion.
     * @param {number} z - The z component of the quaternion.
     * @param {number} w - The w component of the quaternion.
     * @returns {Quat} Self for chaining.
     * @example
     * const q = new pc.Quat();
     * q.set(1, 0, 0, 0);
     *
     * // Outputs 1, 0, 0, 0
     * console.log("The result of the vector set is: " + q.toString());
     */
    set(x: number, y: number, z: number, w: number): Quat;
    /**
     * Sets a quaternion from an angular rotation around an axis.
     *
     * @param {Vec3} axis - World space axis around which to rotate.
     * @param {number} angle - Angle to rotate around the given axis in degrees.
     * @returns {Quat} Self for chaining.
     * @example
     * const q = new pc.Quat();
     * q.setFromAxisAngle(pc.Vec3.UP, 90);
     */
    setFromAxisAngle(axis: Vec3, angle: number): Quat;
    /**
     * Sets a quaternion from Euler angles specified in XYZ order.
     *
     * @param {number|Vec3} ex - Angle to rotate around X axis in degrees. If ex is a Vec3, the
     * three angles will be read from it instead.
     * @param {number} [ey] - Angle to rotate around Y axis in degrees.
     * @param {number} [ez] - Angle to rotate around Z axis in degrees.
     * @returns {Quat} Self for chaining.
     * @example
     * // Create a quaternion from 3 euler angles
     * const q = new pc.Quat();
     * q.setFromEulerAngles(45, 90, 180);
     *
     * // Create the same quaternion from a vector containing the same 3 euler angles
     * const v = new pc.Vec3(45, 90, 180);
     * const r = new pc.Quat();
     * r.setFromEulerAngles(v);
     */
    setFromEulerAngles(ex: number | Vec3, ey?: number, ez?: number): Quat;
    /**
     * Converts the specified 4x4 matrix to a quaternion. Note that since a quaternion is purely a
     * representation for orientation, only the translational part of the matrix is lost.
     *
     * @param {import('./mat4.js').Mat4} m - The 4x4 matrix to convert.
     * @returns {Quat} Self for chaining.
     * @example
     * // Create a 4x4 rotation matrix of 180 degrees around the y-axis
     * const rot = new pc.Mat4().setFromAxisAngle(pc.Vec3.UP, 180);
     *
     * // Convert to a quaternion
     * const q = new pc.Quat().setFromMat4(rot);
     */
    setFromMat4(m: import("./mat4.js").Mat4): Quat;
    /**
     * Set the quaternion that represents the shortest rotation from one direction to another.
     *
     * @param {Vec3} from - The direction to rotate from. It should be normalized.
     * @param {Vec3} to - The direction to rotate to. It should be normalized.
     * @returns {Quat} Self for chaining.
     *
     * {@link https://www.xarg.org/proof/quaternion-from-two-vectors/ Proof of correctness}
     */
    setFromDirections(from: Vec3, to: Vec3): Quat;
    /**
     * Performs a spherical interpolation between two quaternions. The result of the interpolation
     * is written to the quaternion calling the function.
     *
     * @param {Quat} lhs - The quaternion to interpolate from.
     * @param {Quat} rhs - The quaternion to interpolate to.
     * @param {number} alpha - The value controlling the interpolation in relation to the two input
     * quaternions. The value is in the range 0 to 1, 0 generating q1, 1 generating q2 and anything
     * in between generating a spherical interpolation between the two.
     * @returns {Quat} Self for chaining.
     * @example
     * const q1 = new pc.Quat(-0.11, -0.15, -0.46, 0.87);
     * const q2 = new pc.Quat(-0.21, -0.21, -0.67, 0.68);
     *
     * const result;
     * result = new pc.Quat().slerp(q1, q2, 0);   // Return q1
     * result = new pc.Quat().slerp(q1, q2, 0.5); // Return the midpoint interpolant
     * result = new pc.Quat().slerp(q1, q2, 1);   // Return q2
     */
    slerp(lhs: Quat, rhs: Quat, alpha: number): Quat;
    /**
     * Transforms a 3-dimensional vector by the specified quaternion.
     *
     * @param {Vec3} vec - The 3-dimensional vector to be transformed.
     * @param {Vec3} [res] - An optional 3-dimensional vector to receive the result of the transformation.
     * @returns {Vec3} The input vector v transformed by the current instance.
     * @example
     * // Create a 3-dimensional vector
     * const v = new pc.Vec3(1, 2, 3);
     *
     * // Create a 4x4 rotation matrix
     * const q = new pc.Quat().setFromEulerAngles(10, 20, 30);
     *
     * const tv = q.transformVector(v);
     */
    transformVector(vec: Vec3, res?: Vec3): Vec3;
    /**
     * Converts the quaternion to string form.
     *
     * @returns {string} The quaternion in string form.
     * @example
     * const v = new pc.Quat(0, 0, 0, 1);
     * // Outputs [0, 0, 0, 1]
     * console.log(v.toString());
     */
    toString(): string;
}
import { Vec3 } from './vec3.js';