import type { Euler } from "./euler.js";
import type { Matrix3 } from "./matrix3.js";
import type { Vector3 } from "./vector3.js";
import { Vector4 } from "./vector4.js";
/**
 * A quaternion.
 */
export declare class Quaternion extends Vector4 {
    /**
     * Constructs a new {@linkcode Quaternion}.
     * @param x - The X component.
     * @param y - The Y component.
     * @param z - The Z component.
     * @param w - The W component.
     */
    constructor(x?: number, y?: number, z?: number, w?: number);
    /**
     * Creates a new {@linkcode Quaternion} from a rotation matrix.
     * @param matrix - The matrix to construct the quaternion from.
     * @returns A new quaternion.
     */
    static fromMatrix3(matrix: Readonly<Matrix3>): Quaternion;
    /**
     * Creates a new {@linkcode Quaternion} from a rotation in Euler angles.
     * @param degrees - The rotation in Euler angles.
     * @returns A new quaternion.
     */
    static fromEuler(degrees: Readonly<Euler>): Quaternion;
    /**
     * Creates a new {@linkcode Quaternion} from a rotation around an axis.
     * @param axis - The axis around which to rotate.
     * @param degrees - The rotation in degrees.
     * @returns A new quaternion.
     */
    static fromVector3(axis: Readonly<Vector3>, degrees: number): Quaternion;
    /**
     * Creates a new {@linkcode Quaternion} from a {@linkcode Vector4}.
     * @param vector - The vector to copy the components from.
     * @returns A new quaternion.
     */
    static fromVector4(vector: Readonly<Vector4>): Quaternion;
    /**
     * Creates a new {@linkcode Quaternion} from another {@linkcode Quaternion}.
     * @param quaternion - The quaternion to copy.
     * @returns A new quaternion.
     */
    static fromQuaternion(quaternion: Readonly<Quaternion>): Quaternion;
    /**
     * Sets the quaternion to the values of another quaternion.
     * @param quaternion - The quaternion to copy.
     * @returns This instance.
     */
    set(quaternion: Readonly<Quaternion>): this;
    /**
     * Sets all components of the quaternion to the given value.
     * @param value - The value to assign to the components of the quaternion.
     * @returns This instance.
     */
    setValue(value: number): this;
    /**
     * Sets the components of the quaternion to the given values.
     * @param x - The X component for the quaternion.
     * @param y - The Y component for the quaternion.
     * @param z - The Z component for the quaternion.
     * @param w - The W component for the quaternion.
     * @returns This instance.
     */
    setXYZW(x: number, y: number, z?: number, w?: number): this;
    /**
     * Sets the quaternion to the rotation of the given matrix.
     * @param matrix - The matrix describing the rotation of the quaternion.
     * @returns This instance.
     */
    setMatrix3(matrix: Readonly<Matrix3>): this;
    /**
     * Sets the quaternion to a rotation in Euler angles.
     * @param degrees - The rotation in Euler angles.
     * @returns This instance.
     */
    setEuler(degrees: Readonly<Euler>): this;
    /**
     * Sets the quaternion to a rotation around an axis.
     * @param axis - The axis around which to rotate.
     * @param degrees - The rotation in degrees.
     * @returns This instance.
     */
    setVector3(axis: Readonly<Vector3>, degrees: number): this;
    /**
     * Sets the quaternion to the components of a {@linkcode Vector4}.
     * @param vector - The vector to copy.
     * @returns This instance.
     */
    setVector4(vector: Readonly<Vector4>): this;
    /**
     * Normalize the quaternion.
     * @returns This instance.
     */
    normalize(): this;
    /**
     * Invert the quaternion.
     * @returns This instance.
     */
    invert(): this;
    /**
     * Multiply with another quaternion from the right.
     * @param quaternion - The quaternion to multiply with.
     * @returns This instance.
     */
    multiplyR(quaternion: Readonly<Quaternion>): this;
    /**
     * Performs spherical linear interpolation between two rotations, and sets this
     * quaternion to the resulting rotation.
     * @param q1 - The initial rotation.
     * @param q2 - The target rotation.
     * @param t - The location on the scale from `0` to `1`.
     * @returns This instance.
     */
    slerp(q1: Readonly<Quaternion>, q2: Readonly<Quaternion>, t: number): this;
}