Unity C# How do I Instantiate an object with the rigid body constraints unchecked

Question

I want to instantiate something so that when it's made it doesn't have the rigid body constraints on but after a few seconds on again.

Answer 1

Make an object prefab and add a script with this code as a component. (I made a 2D one, just remove the 2D parts if you want to use 3D rigidbody)

using System;
using UnityEngine;

public class DelayedConstraints : MonoBehaviour
{
   private Rigidbody2D rb;
   private DateTime now;
   private DateTime momentToFreeze;

   public int secondsDelayToFreeze;


   void Start()
   {
       rb = GetComponent<Rigidbody2D>();
       now = DateTime.Now;
       momentToFreeze = DateTime.Now.AddSeconds(secondsDelayToFreeze);
   }

   void Update()
   {
       now = DateTime.Now;
       // we compare the hour, minute and second of the 2 times (all 3 for accuracy)

       if (now.Hour == momentToFreeze.Hour && now.Minute == momentToFreeze.Minute && now.Second == momentToFreeze.Second)
        rb.constraints = RigidbodyConstraints2D.FreezeAll;
       /* Possible options for constrains are:
           .FreezeAll
           .FreezePosition
           .FreezePositionX
           .FreezePositionY
           .FreezeRotation
       */
   }
}

Then, make an empty object and attach this code to it.

using UnityEngine;

public class Spawner : MonoBehaviour
{
    public GameObject ourPrefab;

    void Start()
    {
        GameObject obj = Instantiate(ourPrefab, transform.position, transform.rotation);
    }
}

So, what all of this does is: You have a spawner and at the beginning of the game's runtime, it instantiates an object that you have set as a prefab. After the Seconds-delay you have set on that prefab's script passes, its RigidBody's constraints will Freeze.

I mostly focused on the time delay, for more rigidbody constraints, I suggest you read the documentation at https://docs.unity3d.com/ScriptReference/RigidbodyConstraints.html

**EDIT: I forgot to mention, the prefab by default should have the constraints off. Another way is to write rb.constraints = RigidbodyConstraints2D.None; in the Start method.