Unity Physics - Attract(Rigidbody body)

Question

I have this script Gravity.cs

public class Gravity : MonoBehaviour
    {

        public float planetGravity = -10f;

        public void Attract(Rigidbody body)
        {
            Vector2 normalForce = (body.position - transform.position).normalized;
            Vector2 localUp = body.transform.up;

            body.AddForce(normalForce * planetGravity);

            body.rotation = Quaternion.FromToRotation(localUp, normalForce) * body.rotation;
        }
    }

In this script I make a "gravity field", for a 2D sprite of a planet, I then have my player walk around it.

My problem, I want multiple of these planets, all with different gravity fields, When the player is out of the sphere of influence (a trigger sphere collider in unity) the player should be attracted to the closest planet with the highest gravity eg. if the player is exactly between two planets the player should fall to the planet with the highest gravity(or mass idk), how can I do this?

Answer 1

instead of your current method you could use a gravity formula.

F=a*m/d

a is a constant to control the gravity.
m is the mass/size of the planet.
d is the distance from player to planet.

if you apply this for every planet then it should be pretty realistic. maybe you can ignore a planet when the distance is greater than b*m where b is some other constant to control the size

Answer 2

I have recently written about this issue. I will say it here again so that it may be of use:

Use the existing Physics2D. Don't reinvent the wheel. There's a component called PointEffector2D, you're trying to achieve its effects manually, which will end badly if it's not implemented correctly.

Here's the manual for effectors. What you want, is to have inverse squared force mode with a negative number as the force. You don't need a rigidbody on the planet but you do need a Collider2D that will be used by effector.