import { type IQuaternionLike } from "../Maths/math.like.js";
import { Quaternion, Vector3 } from "../Maths/math.vector.js";
import { type DeepImmutable } from "../types.js";
/**
 * Returns the angle in radians between two quaternions
 * @param q1 defines the first quaternion
 * @param q2 defines the second quaternion
 * @returns the angle in radians between the two quaternions
 */
export declare function GetAngleBetweenQuaternions(q1: DeepImmutable<IQuaternionLike>, q2: DeepImmutable<IQuaternionLike>): number;
/**
 * Creates a quaternion from two direction vectors
 * @param a defines the first direction vector
 * @param b defines the second direction vector
 * @returns the target quaternion
 */
export declare function GetQuaternionFromDirections<T extends Vector3>(a: DeepImmutable<T>, b: DeepImmutable<T>): Quaternion;
/**
 * Creates a quaternion from two direction vectors
 * @param a defines the first direction vector
 * @param b defines the second direction vector
 * @param result defines the target quaternion
 * @returns the target quaternion
 */
export declare function GetQuaternionFromDirectionsToRef<T extends Vector3, ResultT extends Quaternion>(a: DeepImmutable<T>, b: DeepImmutable<T>, result: ResultT): ResultT;