import type { AnimationAction, Vector2Like } from "three";
import { AnimationTree } from "./AnimationTree";
/**
 * Configuration for a freeform animation action in the blend tree.
 * Associates an animation action with Cartesian coordinates in 2D space.
 */
export interface FreeformAction {
    /** The Three.js animation action to be played */
    action: AnimationAction;
    /** X coordinate in 2D space (finite number) */
    x: number;
    /** Y coordinate in 2D space (finite number) */
    y: number;
}
/**
 * Freeform blend tree implementation for arbitrary 2D animation blending.
 *
 * Uses Delaunay triangulation to create a mesh from animation actions positioned
 * in arbitrary 2D coordinates, enabling smooth interpolation between animations
 * based on barycentric coordinates within triangles. For points outside the mesh,
 * falls back to nearest edge interpolation for boundary handling.
 *
 * The blend tree automatically constructs a triangulated mesh from input actions
 * and provides seamless blending across the entire 2D space, making it ideal
 * for complex animation systems like movement with multiple speed/direction
 * combinations or facial animation with arbitrary control points.
 *
 * @example Character Movement with Arbitrary Speeds
 * ```typescript
 * // Define movement animations at various speeds and directions
 * const actions = [
 *   { action: idleAction, x: 0, y: 0 },           // Center: idle
 *   { action: walkNorthAction, x: 0, y: 1 },      // North: slow
 *   { action: runNorthAction, x: 0, y: 2 },       // North: fast
 *   { action: walkEastAction, x: 1, y: 0 },       // East: slow
 *   { action: runEastAction, x: 2, y: 0 },        // East: fast
 *   { action: walkNEAction, x: 0.7, y: 0.7 },     // Northeast: diagonal
 *   { action: sprintAction, x: 1.5, y: 1.5 }      // Sprint: very fast diagonal
 * ];
 *
 * const blendTree = new FreeformBlendTree(actions);
 *
 * // Blend to medium speed northeast
 * blendTree.setBlend(0.5, 0.8);
 *
 * // Blend to maximum speed due east
 * blendTree.setBlend(2.0, 0.0);
 * ```
 */
export declare class FreeformBlendTree extends AnimationTree {
    private readonly tempAnchorMap;
    private readonly trackableAnchors;
    private readonly triangles;
    private readonly boundaryEdgeMap;
    private currentX;
    private currentY;
    /**
     * Creates a new freeform blend tree from animation actions positioned in 2D space.
     * Performs Delaunay triangulation to create a mesh for barycentric interpolation.
     * Initializes all actions to stopped state and validates coordinates and durations.
     *
     * @param freeformActions - Array of freeform actions defining the blend space.
     *                         Must contain at least 3 actions with unique coordinates.
     * @throws {Error} When fewer than 3 actions are provided
     * @throws {Error} When any action has non-finite coordinates
     * @throws {Error} When any action coordinates are outside JavaScript's safe range
     * @throws {Error} When multiple actions have the same coordinates
     * @throws {Error} When any animation clip duration is not positive
     * @throws {Error} When actions form degenerate triangulation (all collinear)
     * @see {@link assertValidNumber} for coordinate validation details
     * @see {@link DelaunayTriangulator.triangulate} for triangulation details
     */
    constructor(freeformActions: FreeformAction[]);
    get blendValue(): Vector2Like;
    /**
     * Sets the blend position in 2D Cartesian coordinates to determine animation weights.
     * When the position changes, animation weights are recalculated using barycentric
     * interpolation within triangles or nearest edge interpolation for boundary points.
     *
     * Points inside triangles use barycentric coordinates for smooth 3-way blending.
     * Points outside the mesh use interpolation along the nearest boundary edge.
     *
     * @param x - Target X coordinate in 2D space (finite number)
     * @param y - Target Y coordinate in 2D space (finite number)
     * @throws {Error} When x coordinate is not a finite number
     * @throws {Error} When y coordinate is not a finite number
     * @see {@link assertValidNumber} for coordinate validation details
     *
     * @example
     * ```typescript
     * // Blend to position within the mesh
     * blendTree.setBlend(1.2, 0.8);
     *
     * // Blend to position outside mesh (uses boundary interpolation)
     * blendTree.setBlend(-0.5, 3.0);
     * ```
     */
    setBlend(x: number, y: number): void;
    protected ["onEnterInternal"](): void;
    /**
     * Updates the influence for all anchors in the freeform blend tree.
     * Called when the tree's influence changes but relative weights remain the same.
     * Applies the current tree influence to all triangulated anchors while maintaining
     * their existing weight distribution from the freeform blending calculations.
     */
    protected updateAnchorsInfluence(): void;
    /**
     * Recalculates and updates animation weights based on current blend position.
     *
     * This is the core blending algorithm that:
     * 1. Attempts barycentric interpolation if point lies within any triangle
     * 2. Falls back to nearest boundary edge interpolation for external points
     * 3. Updates the active anchors set with calculated weights
     *
     * The method prioritizes smooth 3-way barycentric blending when possible,
     * providing seamless 2-way edge blending for boundary cases.
     */
    private updateAnchors;
    /**
     * Attempts to apply barycentric weights if the blend point lies within any triangle.
     * Searches through all triangles to find one containing the current blend position
     * and calculates the barycentric coordinates for 3-way interpolation.
     *
     * @param result - Map to store calculated weights for each anchor
     * @returns True if barycentric interpolation was applied, false if point is outside all triangles
     * @see {@link calculateBarycentricWeights} for barycentric coordinate calculation
     */
    private applyBarycentricWeights;
    /**
     * Applies nearest boundary edge interpolation for points outside the triangulated mesh.
     * Finds the closest boundary vertex and interpolates along the nearest boundary edge
     * to provide smooth 2-way blending for external points.
     *
     * The algorithm:
     * 1. Finds the closest anchor among all boundary vertices
     * 2. Identifies the two boundary edges connected to this anchor
     * 3. Determines which edge is closer to the blend point
     * 4. Projects the point onto the edge and calculates interpolation weights
     *
     * @param result - Map to store calculated weights for each anchor
     * @see {@link calculateDistanceSquared} for distance calculations
     * @see {@link calculateDistanceToEdgeSquared} for edge distance calculations
     */
    private applyNearestNeighborWeight;
    /**
     * Sorts triangles by distance from their centroids to the current blend position.
     * This optimization improves performance of barycentric weight calculation by
     * checking closer triangles first, reducing average search time.
     *
     * Called whenever the blend position changes to maintain optimal search order.
     */
    private sortTriangles;
}