import type { AnimationAction } from "three";
import { AnimationTree } from "./AnimationTree";
/**
 * Configuration for a linear animation action in the blend tree.
 * Associates an animation action with a position value on the linear blend axis.
 */
export interface LinearAction {
    /** The animation action to be played */
    action: AnimationAction;
    /** Position value on the linear blend axis where this action is positioned */
    value: number;
}
/**
 * Linear blend tree implementation for 1D animation blending.
 *
 * Manages animation actions positioned along a linear axis, blending
 * between adjacent animations based on a blend value. Interpolates weights
 * between the two closest animations.
 *
 * Action values can be any finite numbers and must be unique.
 *
 * @example
 * ```typescript
 * const blendTree = new LinearBlendTree([
 *   { action: idleAction, value: 0 },
 *   { action: walkAction, value: 0.5 },
 *   { action: runAction, value: 1 }
 * ]);
 *
 * blendTree.setBlend(0.3);
 * ```
 */
export declare class LinearBlendTree extends AnimationTree {
    private readonly anchors;
    private lastLeftAnchor?;
    private lastRightAnchor?;
    private currentBlend;
    /**
     * Creates a new linear blend tree with the specified animation actions.
     * Actions are sorted by their value along the linear axis.
     *
     * @param linearActions - Array of linear actions defining the blend space.
     *                       Must contain at least 2 actions with unique, finite values.
     * @throws {Error} When fewer than 2 actions are provided
     * @throws {Error} When any action has a non-finite value
     * @throws {Error} When multiple actions have the same value
     * @throws {Error} When any animation clip duration is not positive
     */
    constructor(linearActions: LinearAction[]);
    get blendValue(): number;
    /**
     * Sets the blend value to determine animation weights along the linear axis.
     * Recalculates weights to interpolate between the two closest actions.
     * Values outside the action range give full weight to the nearest boundary action.
     *
     * @param value - The target blend value
     * @throws {Error} When the blend value is not a finite number
     */
    setBlend(value: number): void;
    protected ["onEnterInternal"](): void;
    /**
     * Updates the influence for all anchors in the linear blend tree.
     * Called when the tree's influence changes but relative weights remain the same.
     */
    protected updateAnchorsInfluence(): void;
    /**
     * Recalculates and updates animation weights based on the current blend value.
     * Performs linear interpolation between the two actions closest to the blend point.
     */
    private updateAnchors;
}