@woosh/meep-engine/src/engine/network/sim/RewindEngine.d.ts

Pure JavaScript game engine. Fully featured and production ready.

/**
 * Walks the {@link ActionLog} backwards to restore prior component state.
 *
 * For each frame to undo, the engine:
 *   1. Parses the frame's records forward to find record start positions
 *      (a record's full length isn't fixed; it's discovered by reading headers).
 *   2. Iterates record positions in reverse.
 *   3. For each record, reads its prior_state entries and writes them back into
 *      live components via the replication adapter for that component class.
 *
 * Reverse iteration is necessary because multiple actions in the same frame may
 * have mutated the same component; the most recent mutation must be undone
 * first, then the next-most-recent, and so on, ending at the start-of-frame state.
 *
 * Forward replay is just running the existing simulation tick again — that's the
 * orchestrator's job. RewindEngine only handles the backward direction.
 *
 * @author Alex Goldring
 * @copyright Company Named Limited (c) 2025
 */
export class RewindEngine {
    /**
     * @param {{
     *   action_log: ActionLog,
     *   world: EntityComponentDataset,
     *   component_registry: ReplicatedComponentRegistry,
     * }} options
     */
    constructor({ action_log, world, component_registry }: {
        action_log: ActionLog;
        world: EntityComponentDataset;
        component_registry: ReplicatedComponentRegistry;
    });
    /**
     * @type {ActionLog}
     */
    action_log: ActionLog;
    /**
     * @type {EntityComponentDataset}
     */
    world: EntityComponentDataset;
    /**
     * @type {ReplicatedComponentRegistry}
     */
    component_registry: ReplicatedComponentRegistry;
    /**
     * Undo all action records in a single frame, in reverse order.
     * Throws if the frame is not present in the log.
     *
     * @param {number} frame
     */
    undo_frame(frame: number): void;
    /**
     * Undo every frame in `(target_frame, current_frame]` so that the world is
     * left in start-of-`target_frame + 1` state. Equivalently: the world ends
     * up as it was at the END of `target_frame`.
     *
     * Throws if any frame in the range is missing from the log.
     *
     * @param {number} current_frame the most recent frame whose actions are applied
     * @param {number} target_frame the frame whose end-state we want to restore to
     */
    rewind_to(current_frame: number, target_frame: number): void;
    #private;
}
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