import { Curve, Quaternion, Vector3 } from "three";
import { Behaviour } from "../Component.js";
/**
 * Represents a single knot (control point) in a spline curve.
 *
 * Each knot defines a point along the spline with its position, rotation, and tangent handles
 * that control the curve's shape entering and leaving the knot.
 *
 * **Properties:**
 * - **position**: The 3D position of this knot in local space
 * - **rotation**: The orientation at this knot (useful for rotating objects along the spline)
 * - **tangentIn**: The incoming tangent handle controlling the curve shape before this knot
 * - **tangentOut**: The outgoing tangent handle controlling the curve shape after this knot
 *
 * @see {@link SplineContainer} for the container that holds and manages multiple knots
 */
export declare class SplineData {
    /**
     * The 3D position of this knot in local space relative to the SplineContainer.
     */
    position: Vector3;
    /**
     * The orientation at this knot. Can be used to rotate objects following the spline.
     */
    rotation: Quaternion;
    /**
     * The incoming tangent handle controlling the curve shape as it approaches this knot.
     * The magnitude and direction affect the smoothness and curvature of the spline.
     */
    tangentIn: Vector3;
    /**
     * The outgoing tangent handle controlling the curve shape as it leaves this knot.
     * The magnitude and direction affect the smoothness and curvature of the spline.
     */
    tangentOut: Vector3;
}
/**
 * [SplineContainer](https://engine.needle.tools/docs/api/SplineContainer) manages spline curves defined by a series of knots (control points).
 * This component stores spline data and generates smooth curves that can be used for animation paths, camera paths, racing tracks, or any curved path in 3D space.
 *
 * ![](https://cloud.needle.tools/-/media/XIHaiNFsA1IbMZVJepp1aQ.gif)
 *
 * **How It Works:**
 * The spline is defined by an array of {@link SplineData} knots. Each knot contains:
 * - **Position**: The location of the control point
 * - **Rotation**: Orientation at that point (useful for banking/tilting objects along the path)
 * - **Tangents**: Handles that control the curve's smoothness and shape
 *
 * The component uses Catmull-Rom interpolation to create smooth curves between knots. The curve is automatically
 * rebuilt when knots are added, removed, or marked dirty, and all sampling methods return positions in world space.
 *
 * **Key Features:**
 * - Smooth Catmull-Rom curve interpolation
 * - Support for open and closed curves
 * - Dynamic knot management (add/remove at runtime)
 * - World-space sampling with {@link getPointAt} and {@link getTangentAt}
 * - Automatic curve regeneration when modified
 * - Built-in debug visualization
 * - Integrates seamlessly with {@link SplineWalker}
 *
 * **Common Use Cases:**
 * - Camera paths and cinematics
 * - Object movement along curved paths
 * - Racing game tracks and racing lines
 * - Character patrol routes
 * - Procedural road/path generation
 * - Animation curves for complex motion
 * - Cable/rope visualization
 *
 * @example Basic spline setup with knots
 * ```ts
 * const splineObj = new Object3D();
 * const spline = splineObj.addComponent(SplineContainer);
 *
 * // Add knots to define the path
 * spline.addKnot({ position: new Vector3(0, 0, 0) });
 * spline.addKnot({ position: new Vector3(2, 1, 0) });
 * spline.addKnot({ position: new Vector3(4, 0, 2) });
 * spline.addKnot({ position: new Vector3(6, -1, 1) });
 *
 * // Sample a point halfway along the spline
 * const midpoint = spline.getPointAt(0.5);
 * console.log("Midpoint:", midpoint);
 * ```
 *
 * @example Creating a closed loop spline
 * ```ts
 * const loopSpline = gameObject.addComponent(SplineContainer);
 * loopSpline.closed = true; // Makes the spline loop back to the start
 *
 * // Add circular path knots
 * for (let i = 0; i < 8; i++) {
 *   const angle = (i / 8) * Math.PI * 2;
 *   const pos = new Vector3(Math.cos(angle) * 5, 0, Math.sin(angle) * 5);
 *   loopSpline.addKnot({ position: pos });
 * }
 * ```
 *
 * @example Sampling points along a spline
 * ```ts
 * const spline = gameObject.getComponent(SplineContainer);
 *
 * // Sample 10 points along the spline
 * const points: Vector3[] = [];
 * for (let i = 0; i <= 10; i++) {
 *   const t = i / 10; // 0 to 1
 *   const point = spline.getPointAt(t);
 *   points.push(point);
 * }
 *
 * // Get tangent (direction) at 75% along the spline
 * const tangent = spline.getTangentAt(0.75);
 * console.log("Direction at 75%:", tangent);
 * ```
 *
 * @example Dynamic knot manipulation
 * ```ts
 * const spline = gameObject.getComponent(SplineContainer);
 *
 * // Add a new knot dynamically
 * const newKnot = new SplineData();
 * newKnot.position.set(10, 5, 0);
 * spline.addKnot(newKnot);
 *
 * // Remove the first knot
 * spline.removeKnot(0);
 *
 * // Modify existing knot
 * spline.spline[1].position.y += 2;
 * spline.markDirty(); // Tell the spline to rebuild
 * ```
 *
 * @example Using with SplineWalker for animation
 * ```ts
 * // Set up spline path
 * const spline = pathObject.addComponent(SplineContainer);
 * spline.addKnot({ position: new Vector3(0, 0, 0) });
 * spline.addKnot({ position: new Vector3(5, 2, 5) });
 * spline.addKnot({ position: new Vector3(10, 0, 0) });
 *
 * // Make object follow the spline
 * const walker = movingObject.addComponent(SplineWalker);
 * walker.spline = spline;
 * walker.speed = 2; // Units per second
 * walker.loop = true;
 * ```
 *
 * **Debug Visualization:**
 * Add `?debugsplines` to your URL to enable debug visualization, which draws the spline curve as a purple line.
 * You can also enable it programmatically:
 * ```ts
 * spline.debug = true; // Show debug visualization
 * ```
 *
 * @see {@link SplineWalker} - Component for moving objects along a spline path
 * @see {@link SplineData} - The knot data structure used to define spline points
 * @see {@link getPointAt} - Sample positions along the spline
 * @see {@link getTangentAt} - Get direction vectors along the spline
 * @see {@link addKnot} - Add control points to the spline
 * @see {@link removeKnot} - Remove control points from the spline
 *
 * @summary Manages smooth spline curves defined by control point knots
 * @category Splines
 * @group Components
 * @component
 */
export declare class SplineContainer extends Behaviour {
    /**
     * Adds a knot (control point) to the end of the spline.
     *
     * You can pass either a full {@link SplineData} object or a simple object with just a position.
     * When passing a simple object, default values are used for rotation and tangents.
     *
     * The spline curve is automatically marked dirty and will be rebuilt on the next update.
     *
     * @param knot - Either a SplineData object or an object with at least a `position` property
     * @returns This SplineContainer for method chaining
     *
     * @example Add knots with positions only
     * ```ts
     * spline.addKnot({ position: new Vector3(0, 0, 0) })
     *       .addKnot({ position: new Vector3(5, 0, 0) })
     *       .addKnot({ position: new Vector3(5, 0, 5) });
     * ```
     *
     * @example Add a full SplineData knot
     * ```ts
     * const knot = new SplineData();
     * knot.position.set(10, 2, 5);
     * knot.rotation.setFromEuler(new Euler(0, Math.PI / 4, 0));
     * spline.addKnot(knot);
     * ```
     */
    addKnot(knot: SplineData | {
        position: Vector3;
    }): SplineContainer;
    /**
     * Removes a knot (control point) from the spline.
     *
     * You can remove a knot either by its numeric index in the spline array or by passing
     * a reference to the SplineData object itself.
     *
     * The spline curve is automatically marked dirty and will be rebuilt on the next update.
     *
     * @param index - Either the numeric index of the knot to remove, or the SplineData object reference
     * @returns This SplineContainer for method chaining
     *
     * @example Remove knot by index
     * ```ts
     * spline.removeKnot(0); // Remove first knot
     * spline.removeKnot(spline.spline.length - 1); // Remove last knot
     * ```
     *
     * @example Remove knot by reference
     * ```ts
     * const knotToRemove = spline.spline[2];
     * spline.removeKnot(knotToRemove);
     * ```
     */
    removeKnot(index: number | SplineData): SplineContainer;
    /**
     * Samples a point on the spline at a given parametric position (in world space).
     *
     * The parameter `t` ranges from 0 to 1, where:
     * - `0` = start of the spline
     * - `0.5` = middle of the spline
     * - `1` = end of the spline
     *
     * The returned position is in world space, accounting for the SplineContainer's transform.
     * Values outside 0-1 are clamped to the valid range.
     *
     * @param to01 - Parametric position along the spline (0 to 1)
     * @param target - Optional Vector3 to store the result (avoids allocation)
     * @returns The world-space position at parameter `t`
     *
     * @example Sample multiple points along the spline
     * ```ts
     * // Sample 20 evenly-spaced points
     * const points: Vector3[] = [];
     * for (let i = 0; i <= 20; i++) {
     *   const t = i / 20;
     *   points.push(spline.getPointAt(t));
     * }
     * ```
     *
     * @example Using a target vector for efficiency
     * ```ts
     * const reusableVector = new Vector3();
     * for (let i = 0; i < 100; i++) {
     *   const point = spline.getPointAt(i / 100, reusableVector);
     *   // Use point...
     * }
     * ```
     *
     * @see {@link getTangentAt} to get the direction at a point
     */
    getPointAt(to01: number, target?: Vector3): Vector3;
    /**
     * Marks the spline as dirty, causing it to be rebuilt on the next update frame.
     *
     * Call this method whenever you manually modify the spline data (knot positions, rotations, or tangents)
     * to ensure the curve is regenerated. This is done automatically when using {@link addKnot} or {@link removeKnot}.
     *
     * @example Modifying knots and marking dirty
     * ```ts
     * // Modify existing knot positions
     * spline.spline[0].position.y += 2;
     * spline.spline[1].position.x -= 1;
     *
     * // Tell the spline to rebuild
     * spline.markDirty();
     * ```
     *
     * @example Animating knot positions
     * ```ts
     * update() {
     *   const time = this.context.time.time;
     *   // Animate knot positions
     *   for (let i = 0; i < spline.spline.length; i++) {
     *     spline.spline[i].position.y = Math.sin(time + i) * 2;
     *   }
     *   spline.markDirty(); // Rebuild curve each frame
     * }
     * ```
     */
    markDirty(): void;
    /**
     * Samples the tangent (direction) vector on the spline at a given parametric position (in world space).
     *
     * The tangent represents the forward direction of the curve at point `t`. This is useful for:
     * - Orienting objects along the spline (facing the direction of travel)
     * - Calculating banking/tilting for vehicles on the path
     * - Understanding the curve's direction at any point
     *
     * The parameter `t` ranges from 0 to 1 (same as {@link getPointAt}).
     * The returned vector is normalized and in world space, accounting for the SplineContainer's rotation.
     *
     * @param t - Parametric position along the spline (0 to 1)
     * @param target - Optional Vector3 to store the result (avoids allocation)
     * @returns The normalized tangent vector in world space at parameter `t`
     *
     * @example Orient an object along the spline
     * ```ts
     * const position = spline.getPointAt(0.5);
     * const tangent = spline.getTangentAt(0.5);
     *
     * object.position.copy(position);
     * object.lookAt(position.clone().add(tangent)); // Face along the spline
     * ```
     *
     * @example Calculate velocity direction for a moving object
     * ```ts
     * let t = 0;
     * update() {
     *   t += this.context.time.deltaTime * 0.2; // Speed
     *   if (t > 1) t = 0; // Loop
     *
     *   const pos = spline.getPointAt(t);
     *   const direction = spline.getTangentAt(t);
     *
     *   movingObject.position.copy(pos);
     *   movingObject.quaternion.setFromUnitVectors(
     *     new Vector3(0, 0, 1),
     *     direction
     *   );
     * }
     * ```
     *
     * @see {@link getPointAt} to get the position at a point
     */
    getTangentAt(t: number, target?: Vector3): Vector3;
    /**
     * Whether the spline forms a closed loop.
     *
     * **When `true`:**
     * - The spline connects the last knot back to the first knot, forming a continuous loop
     * - Perfect for racing tracks, patrol routes, or any circular path
     * - Parameter `t=1` will smoothly connect back to `t=0`
     *
     * **When `false` (default):**
     * - The spline is open, with distinct start and end points
     * - Suitable for one-way paths, camera movements, or linear progressions
     *
     * Changing this property marks the spline as dirty and triggers a rebuild.
     *
     * @example Create a circular patrol route
     * ```ts
     * const patrol = gameObject.addComponent(SplineContainer);
     * patrol.closed = true; // Loop back to start
     *
     * // Add points in a circle
     * for (let i = 0; i < 8; i++) {
     *   const angle = (i / 8) * Math.PI * 2;
     *   patrol.addKnot({
     *     position: new Vector3(Math.cos(angle) * 10, 0, Math.sin(angle) * 10)
     *   });
     * }
     * ```
     *
     * @default false
     */
    set closed(value: boolean);
    get closed(): boolean;
    private _closed;
    /**
     * Array of knots (control points) that define the spline curve.
     *
     * Each element is a {@link SplineData} object containing position, rotation, and tangent information.
     * You can directly access and modify this array, but remember to call {@link markDirty} afterwards
     * to trigger a curve rebuild.
     *
     * **Best practices:**
     * - Use {@link addKnot} and {@link removeKnot} methods for automatic dirty marking
     * - If modifying knots directly, always call {@link markDirty} afterwards
     * - The order of knots determines the path direction
     *
     * @example Direct array access
     * ```ts
     * console.log(`Spline has ${spline.spline.length} knots`);
     *
     * // Access first knot
     * const firstKnot = spline.spline[0];
     * console.log("Start position:", firstKnot.position);
     *
     * // Modify and mark dirty
     * spline.spline[2].position.y += 5;
     * spline.markDirty();
     * ```
     *
     * @see {@link SplineData} for the knot data structure
     * @see {@link addKnot} for adding knots (auto marks dirty)
     * @see {@link removeKnot} for removing knots (auto marks dirty)
     * @see {@link markDirty} to trigger rebuild after manual modifications
     */
    spline: SplineData[];
    /**
     * Enables visual debug rendering of the spline curve.
     *
     * When enabled, the spline is rendered as a purple line in the scene, making it easy to
     * visualize the path during development. The debug line automatically updates when the spline is modified.
     *
     * **Debug visualization:**
     * - Purple line showing the complete curve path
     * - Automatically rebuilds when spline changes
     * - Line resolution based on number of knots (10 segments per knot)
     *
     * **Tip:** You can also enable debug visualization globally for all splines by adding `?debugsplines`
     * to your URL.
     *
     * @example Enable debug visualization
     * ```ts
     * const spline = gameObject.addComponent(SplineContainer);
     * spline.debug = true; // Show purple debug line
     *
     * // Add some knots to see the visualization
     * spline.addKnot({ position: new Vector3(0, 0, 0) });
     * spline.addKnot({ position: new Vector3(5, 2, 0) });
     * spline.addKnot({ position: new Vector3(10, 0, 5) });
     * ```
     */
    set debug(debug: boolean);
    /**
     * The Three.js Curve object generated from the spline knots.
     *
     * This is the underlying curve implementation (typically a CatmullRomCurve3) that's used for
     * all position and tangent sampling. The curve is automatically regenerated when the spline
     * is marked dirty.
     *
     * **Note:** This curve is in local space relative to the SplineContainer. Use {@link getPointAt}
     * and {@link getTangentAt} methods to get world-space results.
     *
     * @returns The generated Three.js Curve, or null if not yet built
     */
    get curve(): Curve<Vector3> | null;
    /**
     * Whether the spline needs to be rebuilt due to modifications.
     *
     * The spline is marked dirty when:
     * - Knots are added via {@link addKnot}
     * - Knots are removed via {@link removeKnot}
     * - {@link markDirty} is called manually
     * - The {@link closed} property is changed
     *
     * The curve is automatically rebuilt on the next update frame when dirty.
     *
     * @returns `true` if the spline needs rebuilding, `false` otherwise
     */
    get isDirty(): boolean;
    private _isDirty;
    private _curve;
    private _builtCurve;
    private _debugLine;
    /** @internal */
    awake(): void;
    /** @internal */
    update(): void;
    private buildCurve;
    private buildDebugCurve;
}
