I am creating a Space simultation in Unity using Newtons Law of gravitation and Centripetal force calculations to re-create the motion of the planets. Recently i have tried to implement realistic masses such as 3.285e+23 and i have converted them to managable numbers using a massScale 1e-24f. but since implementing these new masses and converting them, the smaller planet of the three has started deleting itself shortly after runtime without any error being thrown. I will also add that i dont have any sort of Destroy Line in my code either.
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PlanetVelocity : MonoBehaviour
{
private Gravity _gravity;
public float v;
public bool debugBool;
public GameObject Sun;
private Rigidbody rb;
private Vector3 dif;
public static List<GameObject> AllPlanets;
private const float distScale = 1e-7f;
private const float massScale = 1e-24f;
private const float gravity = 6.674e-11f;
public float mass = 5.972e24f;
private Vector3 motion;
[Header("Orbital Data")]
public float velocity = 29.8f;
public float distance = 148900000f;
//TODO: Convert weight units to KG and use realistic weights for planetary bodies
/*Calculate velocity using v = sqrt[(G M )/r]*/
/*Get the Planet to look at the sun*/
/*Apply V to the transform.right of the planet to have perpendicular motion*/
void Start()
{
_gravity = FindObjectOfType<Gravity>();
rb = GetComponent<Rigidbody>();
rb.mass = mass * massScale;
}
void DebugClass()
{
if(debugBool)
{
Debug.Log($"Mass Scale {rb.mass}");
//Debug.DrawRay(gameObject.transform.position, motion, Color.red);
// Debug.Log($"Calculated Velocity = {v} Difference {dif} Motion {motion}");
}
}
void ObjectLook()
{
transform.LookAt(Sun.transform);
}
// Update is called once per frame
void Update()
{
DebugClass();
ObjectLook();
Vector3 sunPos = new Vector3(Sun.transform.position.x, Sun.transform.position.y, Sun.transform.position.z);
Vector3 planetPos = new Vector3(gameObject.transform.position.x, gameObject.transform.position.y,
gameObject.transform.position.z);
Vector3 dif = sunPos - planetPos;
float r = dif.sqrMagnitude;
v = Mathf.Sqrt(_gravity.f * rb.mass) / r;
//v = Mathf.Sqrt(_gravity.G * rb.mass / r ) ;
Vector3 motion = transform.up * v;
if (gameObject.transform.position.x > 0 && gameObject.transform.position.y > 0)
{
motion.x = Math.Abs(motion.x);
motion.y = -Math.Abs(motion.y);
}
if (gameObject.transform.position.x > 0 && gameObject.transform.position.y < 0)
{
motion.x = -Math.Abs(motion.x);
motion.y = -Math.Abs(motion.y);
}
rb.velocity = motion;
}
}
and here is my script controlling gravitational pull towards the sun, based off of what game objects are withing the sphere collider range of the sun.
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Gravity : MonoBehaviour
{
public float f; //force
private const float massScale = 1e-24f;
public float mass = 1.989e+30f;
public float G = 6.674e-11f; //Gravitational Constant
private Rigidbody m1;//Mass 1 The Sun ( this Game Object)
private Rigidbody m2;//Mass 2 Planet
private Vector3 r1;
public Vector3 FORCE;
public bool debugBool;
void Start()
{
Time.timeScale = 50f;
}
private void Awake()
{
m1 = GetComponent<Rigidbody>();
m1.mass = mass * massScale;
}
private void DebugClass()
{
if (debugBool)
{
Debug.Log(m2.velocity);
Debug.Log("TRIGGERED");
Debug.Log($"r1 {r1.normalized} FORCE {FORCE}");
}
}
private void Update()
{
DebugClass();
}
private void OnTriggerStay(Collider other)
{
//declares rigidbody locally
Rigidbody m2;
//assigns other objects rigidbody to m2
m2 = other.gameObject.GetComponent<Rigidbody>();
// get sun position
Vector3 Sun = new Vector3(gameObject.transform.position.x, gameObject.transform.position.y, gameObject.transform.position.z);
// planet
Vector3 otherPlanet = new Vector3(other.gameObject.transform.position.x, other.gameObject.transform.position.y, other.gameObject.transform.position.z);
//Difference between each object
Vector3 r1 = Sun - otherPlanet;
//Difference between each object squared
float r2 = r1.sqrMagnitude;
float distance = r1.magnitude;
///<summary>
/// Calculates Force by Mutliplying Gravitational
/// constant by the mass of each object divided
/// by the distance between each object squared
/// <summary>
f = G * m1.mass * m2.mass / r2;
//Assigns the value r1 normalized between 0 and 1
//multiplied by F independent of frames per second
Vector3 FORCE = r1.normalized * f * Time.deltaTime;
// Adds force to the other game objects rigidbody using the FORCE vector
// Using the Force force mode
m2.AddForce(FORCE);
}
}
I had issues with extremely small float numbers on my Rigidbody transform and thus unity was deactivating the game object before it overflowed, my solution was to multiply the physic calculations i used by a 'PhysicsMultiplier' and this solved my issues completely