196 lines
9.5 KiB
C#
196 lines
9.5 KiB
C#
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/// ---------------------------------------------
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/// Ultimate Character Controller
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/// Copyright (c) Opsive. All Rights Reserved.
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/// https://www.opsive.com
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/// ---------------------------------------------
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namespace Opsive.UltimateCharacterController.Motion
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{
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using UnityEngine;
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/// <summary>
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/// Allows for a user-defined path that objects can follow.
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/// </summary>
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public class Path : MonoBehaviour
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{
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[Tooltip("The points which represent the curve.")]
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[SerializeField] protected Vector3[] m_ControlPoints;
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public Vector3[] ControlPoints { get { return m_ControlPoints; } set { m_ControlPoints = value; } }
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private CubicBezierCurve[] m_Curve;
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/// <summary>
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/// Initialize the default values.
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/// </summary>
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private void Awake()
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{
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if (m_ControlPoints == null || m_ControlPoints.Length <= 1) {
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return;
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}
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m_Curve = new CubicBezierCurve[(m_ControlPoints.Length / 3)];
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for (int i = 0; i < m_Curve.Length; ++i) {
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var startIndex = i * 3;
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m_Curve[i] = new CubicBezierCurve(transform.TransformPoint(m_ControlPoints[startIndex]), transform.TransformPoint(m_ControlPoints[startIndex + 1]),
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transform.TransformPoint(m_ControlPoints[startIndex + 2]), transform.TransformPoint(m_ControlPoints[startIndex + 3]));
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}
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}
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/// <summary>
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/// Returns the tangent of the curve near the specified position.
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/// </summary>
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/// <param name="position">The position to retrieve the tangent of.</param>
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/// <param name="index">The index of the last curve segnement.</param>
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/// <returns>The tangent of the curve near the specified position.</returns>
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public Vector3 GetTangent(Vector3 position, ref int index)
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{
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var time = m_Curve[index].GetTime(position);
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if (time == 1 && index < m_Curve.Length - 1) {
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// If the time is equal to 1 then the position is at an endpoint. Determine if the current curve is closer to the given position or if the next curve is closer.
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var distance = (m_Curve[index].GetClosestPoint(position) - position).sqrMagnitude;
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var nextDistance = (m_Curve[index + 1].GetClosestPoint(position) - position).sqrMagnitude;
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if (nextDistance < distance) {
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// The next curve is closer - increase the index and retrieve a new time.
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index++;
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time = m_Curve[index].GetTime(position);
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}
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} else if (time == 0 && index > 0) {
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// If the time is equal to 0 then the position is at an endpoint. Determine if the current curve is closer to the given position or if the previous curve is closer.
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var distance = (m_Curve[index].GetClosestPoint(position) - position).sqrMagnitude;
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var prevDistance = (m_Curve[index - 1].GetClosestPoint(position) - position).sqrMagnitude;
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if (prevDistance < distance) {
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// The previous curve is closer - decrease the index and retrieve a new time.
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index--;
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time = m_Curve[index].GetTime(position);
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}
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}
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return m_Curve[index].GetTangent(time);
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}
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/// <summary>
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/// Returns the tangent of the curve near the specified position.
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/// </summary>
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/// <param name="position">The position to retrieve the tangent of.</param>
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/// <param name="index">The index of the last curve segnement.</param>
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/// <returns>The tangent of the curve near the specified position.</returns>
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public Vector3 GetClosestPoint(Vector3 position, ref int index)
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{
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var time = m_Curve[index].GetTime(position);
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if (time == 1 && index < m_Curve.Length - 1) {
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// If the time is equal to 1 then the position is at an endpoint. Determine if the current curve is closer to the given position or if the next curve is closer.
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var distance = (m_Curve[index].GetClosestPoint(position) - position).sqrMagnitude;
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var nextDistance = (m_Curve[index + 1].GetClosestPoint(position) - position).sqrMagnitude;
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if (nextDistance < distance) {
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// The next curve is closer - increase the index and retrieve a new time.
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index++;
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}
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} else if (time == 0 && index > 0) {
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// If the time is equal to 0 then the position is at an endpoint. Determine if the current curve is closer to the given position or if the previous curve is closer.
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var distance = (m_Curve[index].GetClosestPoint(position) - position).sqrMagnitude;
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var prevDistance = (m_Curve[index - 1].GetClosestPoint(position) - position).sqrMagnitude;
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if (prevDistance < distance) {
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// The previous curve is closer - decrease the index and retrieve a new time.
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index--;
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}
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}
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return m_Curve[index].GetClosestPoint(position);
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}
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/// <summary>
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/// Represents one segment of a cubic bezier curve.
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/// </summary>
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public class CubicBezierCurve
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{
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private const int c_StepCount = 300;
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private Vector3 m_P0;
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private Vector3 m_P1;
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private Vector3 m_P2;
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private Vector3 m_P3;
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/// <summary>
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/// Four parameter constructor.
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/// </summary>
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/// <param name="p0">The first point that makes up the curve.</param>
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/// <param name="p1">The second point that makes up the curve.</param>
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/// <param name="p2">The third point that makes up the curve.</param>
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/// <param name="p3">The fourth point that makes up the curve.</param>
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public CubicBezierCurve(Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3)
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{
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m_P0 = p0;
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m_P1 = p1;
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m_P2 = p2;
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m_P3 = p3;
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}
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/// <summary>
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/// Returns the point of the bezier curve at the normalized position of the curve.
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/// </summary>
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/// <param name="time">The normalized position within the curve.</param>
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/// <returns>The point of the bezier curve at the normalized position of the curve.</returns>
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public Vector3 GetPoint(float time)
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{
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return (((-m_P0 + 3 * (m_P1 - m_P2) + m_P3) * time + (3 * (m_P0 + m_P2) - 6 * m_P1)) * time + 3 * (m_P1 - m_P0)) * time + m_P0;
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}
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/// <summary>
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/// Returns the tangent. This tangent is the first derivative of the curve.
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/// </summary>
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/// <param name="time">The normalized position within the curve.</param>
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/// <returns>The tangent of the curve.</returns>
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public Vector3 GetTangent(float time)
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{
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return (3 * (1 - time) * (1 - time) * (m_P1 - m_P0) + 6 * (1 - time) * time * (m_P2 - m_P1) + 3 * time * time * (m_P3 - m_P2)).normalized;
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}
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/// <summary>
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/// Returns the closest time at the specified position.
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/// </summary>
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/// <param name="position">The position to retrieve the time of.</param>
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/// <param name="endCap">Should the end cap be included?</param>
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/// <returns>The closest time at the specified position.</returns>
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public float GetTime(Vector3 position)
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{
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return GetTime(position, 0, 1);
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}
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/// <summary>
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/// Returns the closest time at the specified position.
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/// </summary>
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/// <param name="position">The position to retrieve the time of.</param>
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/// <param name="minTime">The minimum time to search within the curve.</param>
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/// <param name="maxTime">The maximum time to search within the curve.</param>
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/// <returns>The closest time at the specified position.</returns>
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public float GetTime(Vector3 position, float minTime, float maxTime)
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{
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float closestTime = 0f;
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float closestDistance = float.MaxValue;
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float step = (maxTime - minTime) / c_StepCount;
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var steps = c_StepCount + 1;
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// Walk the curve looking for the closest point to the specified position. Store the closest point and return the corresponding time to that point.
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for (int i = 0; i < steps; ++i) {
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var t = minTime + step * i;
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var distance = (GetPoint(t) - position).sqrMagnitude;
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if (distance < closestDistance) {
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closestDistance = distance;
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closestTime = t;
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}
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}
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return closestTime;
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}
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/// <summary>
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/// Returns the closest point on the curve to the specified position.
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/// </summary>
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/// <param name="position">The position to retrieve the closest point on the curve of.</param>
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/// <param name="endCap">Should the curve's end cap be included?</param>
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/// <returns>The closest point on the curve to the specified position.</returns>
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public Vector3 GetClosestPoint(Vector3 position)
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{
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return GetPoint(GetTime(position));
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}
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}
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}
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}
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