import { type LifecycleMethod, LifecycleMethodOptions } from "./engine_lifecycle_functions_internal.js";
/**
 * Register a callback in the engine context created event.
 * This happens once per context (after the context has been created and the first content has been loaded)
 * @param cb The callback to be called
 * @returns A function that can be called to unregister the callback
 * @example
 * ```ts
 * onInitialized((ctx : Context) => {
 *     // do something
 * }
 * ```
 * */
export declare function onInitialized(cb: LifecycleMethod, opts?: LifecycleMethodOptions): () => void;
/**
 * Register a callback before the engine context is cleared.
 * This happens if e.g. `<needle-engine src>` changes
 */
export declare function onClear(cb: LifecycleMethod, opts?: LifecycleMethodOptions): () => void;
/**
 * Register a callback in the engine before the context is destroyed
 * This happens once per context (before the context is destroyed)
 */
export declare function onDestroy(cb: LifecycleMethod, opts?: LifecycleMethodOptions): () => void;
/** Register a callback in the engine start event.
 * This happens once at the beginning of a frame
 * (e.g. once when the method is registered, after <needle-engine> is created or the src has changed)
 * @param cb The callback to be called. Optionally return a function that will be called when the onStart callback is removed again
 * @returns A function that can be called to unregister the callback
 * @example
 * ```ts
 * onStart((ctx : Context) => {
 *     // do something
 *     console.log("Needle Engine: onStart registered")
 *     // optional to cleanup:
 *     return () => { console.log("OnStart removed") }
 * }
 * ```
 * */
export declare function onStart(cb: LifecycleMethod, opts?: LifecycleMethodOptions): () => void;
/** Register a callback in the engine update event
 * This is called every frame
 * @param cb The callback to be called
 * @returns A function that can be called to unregister the callback
 * @example
 * ```ts
 * onUpdate((ctx : Context) => {
 *     // do something
 *     console.log("Needle Engine: onUpdate registered")
 *     // optional to cleanup:
 *     return () => { console.log("onUpdate removed") }
 * }
 * ```
 * */
export declare function onUpdate(cb: LifecycleMethod, opts?: LifecycleMethodOptions): () => void;
/** Register a callback in the engine onBeforeRender event
 * This is called every frame before the main camera renders
 * @param cb The callback to be called
 * @returns A function that can be called to unregister the callback
 * @example
 * ```ts
 * onBeforeRender((ctx : Context) => {
 *     // do something
 * }
 * ```
 * */
export declare function onBeforeRender(cb: LifecycleMethod, opts?: LifecycleMethodOptions): () => void;
/**
 * Register a callback in the engine onAfterRender event
 * This is called every frame after the main camera has rendered
 * @param cb The callback to be called
 * @returns A function that can be called to unregister the callback
 * @example
 * ```ts
 * const unsubscribe = onAfterRender((ctx : Context) => {
 *    // do something...
 *    console.log("After render");
 *    // if you want to unsubscribe after the first call:
 *    unsubscribe();
 * });
 * ```
 */
export declare function onAfterRender(cb: LifecycleMethod, opts?: LifecycleMethodOptions): () => void;