Find Rigidbody in Ancestry

Questions & Answers
1

Hey guys, quick question. I have a GameObject, “Tank”, with a rigidbody component. The Tank has children, grandchildren, great-grandchildren, and so-on. Children of every depth are dynamically created and removed during runtime. Some of these children are “Turrets”, which ‘kick’ when they fire. I need them to be able to access the rigidbody of the Tank regardless of their depth.

But here’s the kicker: “Tank” may also have a parent, so I can’t use ‘root.’ I also may have an arbitrary number of tanks, turrets, everything.

So, what I need is a way for an object to find a rigidbody in its ancestry. That is, search all of it’s parents (and their parents and so on) for a rigidbody to apply this ‘kick’ impulse to.

Any ideas? Perhaps a custom recursive function is in order, or is there an easier vanilla way?

(Using JavaScript please!) Thanks fellas!

2

Here’s my implementation - used as an extension on a game object:

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System.Text;

public static class GameObjectExtensions 
{
	
	
	public static T FirstAncestorOfType<T>(this GameObject gameObject) where T : Component
	{
		var t = gameObject.transform.parent;
		T component = null;
		while (t != null && (component = t.GetComponent<T>()) == null)
		{
			t = t.parent;
		}
		return component;
	}
	
	public static T LastAncestorOfType<T>(this GameObject gameObject) where T : Component
	{
		var t = gameObject.transform.parent;
		T component = null;
		while (t != null)
		{
			var c = t.gameObject.GetComponent<T>();
			if (c != null)
			{
				component = c;
			}
			t = t.parent;
		}
		return component;
	}
	
	
}

Usage from c#

  var rbdy = gameObject.FirstAncestorOfType<RigidBody>();

From JS (the GameObjectExtensions class must be in Plugins/Standard Assets)

   var rbdy = GameObjectExtensions.FirstAncestorOfType.<RigidBody>(gameObject);