[Solved]How to make a planet gravity that affect asteroid ?

Questions & Answers
1

Hi, as you can read in the title i want to know how to make a planet gravity that affect the asteroids with rigidbody, and if it hit something big the asteroid will get out of the planete orbit.

that is what i did:

var Forward_Speed : float = 0.2;
var Direction : Transform;

var Planet : Transform;
var Speed : float = 0.8;

function Start() {
	Gravity = 0.00;
}
function LateUpdate () 
{	
	rigidbody.AddForce(Direction.TransformDirection(Vector3.forward * Forward_Speed * Time.deltaTime));
	
	transform.RotateAround(Planet.transform.position, Vector3.up,Speed * Time.deltaTime);
}

Thank you in advance and sorry for my bad english :slight_smile:

2

Have you checked the planetary gravity script on UnityWiki?
Here

It will give you a starting place for your gravity script.

I wouldn’t do important physics stuff like gravity inside of LateUpdate(). You should do those kinds of calculations in Update() or FixedUpdate().

Also, if you want to have something like have a gravitational radius you just need to:

  1. get the distance between attracting object and the attracted object. Do this by saying:

    var distance = Vector3.Distance(attractingObject.transform.position, attractedObject.transform.position);

or

var distance = attractingObject.transform.position - attractedObject.transform.position;

  1. create an if statement to check if your attracted object is inside your attracting object’s gravitational radius:

    var gravitationalRadius : int;

    function Update(){

    //Do stuff

if ( distance <= gravitationalRadius){

   // Do gravitational physics stuff here

}

    }

3

Did this Same thing for my game here .

void OnTriggerStay(Collider Me)
{
	GravDir = PlanetPos.transform.position - transform.position;
	if(Me.gameObject.tag == "GravityField")
	{
		rigidbody.useGravity = false; gravity, or whatever
		transform.position = GravDir;
	}	
		

}
	 void OnTriggerExit(Collider Me)
{
	if(Me.gameObject.tag == "GravityField")
	{
		rigidbody.useGravity = true;// depending if you want to re-apply
		rigidbody.constantForce.force = Vector3.zero;
		addingForce = false;	
	}
}

Make sure that you attach a large sphere collider to the planet, that is triggered, and put this code on the ateroids.

4

I have made video to simulate realistic asteroid gravity.
Take a look here : Gravity Simulation