PhysicsSimComponent.cs

using UnityEngine;
using UnityEngine.Timeline;

public class PhysicsSimComponent : MonoBehaviour, ITimeControl
{
    private Vector3[] positions, velocitys, angularVelocitys;
    private Quaternion[] rotations;

    private Rigidbody[] rigidbodys;

    private double preTime = 0;

    public void OnControlTimeStart()
    {
        Physics.autoSimulation = false;

        rigidbodys = FindObjectsOfType<Rigidbody>();

        positions = new Vector3[rigidbodys.Length];
        velocitys = new Vector3[rigidbodys.Length];
        angularVelocitys = new Vector3[rigidbodys.Length];
        rotations = new Quaternion[rigidbodys.Length];

        for (int i = 0; i < rigidbodys.Length; i++)
        {
            positions[i] = rigidbodys[i].position;
            velocitys[i] = rigidbodys[i].velocity;
            angularVelocitys[i] = rigidbodys[i].angularVelocity;
            rotations[i] = rigidbodys[i].rotation;
        }
    }

    public void OnControlTimeStop()
    {
        Physics.autoSimulation = true;

        if (!Application.isPlaying)
        {
            ResetPhysicsObjects();
        }

        rigidbodys = null;
        positions = null;
        velocitys = null;
        angularVelocitys = null;
    }

    public void SetTime(double time)
    {
        var deltaTime = time - preTime;
        preTime = time;

        if (deltaTime == 0)
            return;
        if (deltaTime > 0)
        {
            while( deltaTime > Time.fixedDeltaTime)
            {
                Physics.Simulate(Time.fixedDeltaTime);
                deltaTime -= Time.fixedDeltaTime;
            }
        }
        else
        {
            ResetPhysicsObjects();
            var diffTime = time;
            while (diffTime > Time.fixedDeltaTime)
            {
                Physics.Simulate(Time.fixedDeltaTime);
                diffTime -= Time.fixedDeltaTime;
            }
        }
    }

    void ResetPhysicsObjects()
    {
        for (int i = 0; i < rigidbodys.Length; i++)
        {
            if (rigidbodys[i] == null)
                continue;
            rigidbodys[i].transform.position = positions[i];
            rigidbodys[i].transform.rotation = rotations[i];
            rigidbodys[i].velocity = velocitys[i];
            rigidbodys[i].angularVelocity = angularVelocitys[i];
        }
    }
}