Space Gravity

Unity Engine
1

I have been working on this script for some time…

#pragma strict

var g : GameObject[];
var x = 0.0;
var y = 0.0;
var z = 0.0;
var p = 0;

var xr = 0.0;
var yr = 0.0;
var zr = 0.0;

//Newtons
var fx = 0.0;
var fy = 0.0;
var fz = 0.0;

//6.674×10−11 N m2 kg−2
var G = 1.0;

//Killograms
var m1 = 1000.0;
var m2 = 1500.0;
var r = 10.0 ;

function Start () {
	G = m1 * 0.00000000570345;
}

function Update () {
	g = GameObject.FindGameObjectsWithTag ("Planet");
	
	Calc();
	xr = (transform.position.x - x); 
	fx = (G * (m1 * m1)) * ((m1 * m2) / (xr * xr));
	yr = (transform.position.y - y); 
	fy = (G * (m1 * m1)) * ((m1 * m2) / (yr * yr));
	zr = (transform.position.z - z); 
	fz = (G * (m1 * m1)) * ((m1 * m2) / (zr * zr));
}

function FixedUpdate () {
    rigidbody.AddRelativeForce (Vector3.right * fx);
    rigidbody.AddRelativeForce (Vector3.up * fy);
    rigidbody.AddRelativeForce (Vector3.forward * fz);
}

function Calc () {
	if (p > g.Length - 1){
		p = 0;
	}
	x = (x + (g[p].transform.position.x)) / g.length;
	y = (y + (g[p].transform.position.y)) / g.length;
	z = (z + (g[p].transform.position.z)) / g.length;
	p++;
}

When I run this I have some issues with running into infinity. Can someone fix it or give me a better script.

2

Not sure I understand your problem… I assume this is trying to calculate gravitational pull for the planets?

On a side note you should move

g = GameObject.FindGameObjectsWithTag (“Planet”);

to the Start function (performance improvement)

3

I am trying to calculate the gravitational pull, I’ll also move the g thing. thx

4

You’ve told us what you think it should do. You haven’t told us what the problem is.

5

Well I have gotten all the math to workout now but the script…

#pragma strict

var g : GameObject[];
var p = 0;

//Newtons
var fx = 0.0;
var fy = 0.0;
var fz = 0.0;

//6.674×10−11 N m2 kg−2
var G = 1.0;

//kg
var mass = 1000;
var mas : int;

var xf : float;
var yf : float;
var zf : float;

var x : float;
var y : float;
var z : float;

function Start () {
	G = mass * 0.00000000570345;
	g = GameObject.FindGameObjectsWithTag ("Planet");
}

function FixedUpdate () {
    rigidbody.AddRelativeForce (Vector3.right * fx);
    rigidbody.AddRelativeForce (Vector3.up * fy);
    rigidbody.AddRelativeForce (Vector3.forward * fz);
}

function Update () {
	if (g[p] == this.gameObject) {
		if (p < g.Length - 1){
			p ++;
		}else{
			p = 0;
		}
	}else{
		
		x = (transform.position.x - g[p].transform.position.x);
		y = (transform.position.y - g[p].transform.position.y);
		z = (transform.position.z - g[p].transform.position.z);
		
		xf = (G * ((mass * mass) * (mass * mas)) / (x * x));
		yf = (G * ((mass * mass) * (mass * mas)) / (y * y));
		zf = (G * ((mass * mass) * (mass * mas)) / (z * z));
		
		if (x > 0) {
			fx = fx + xf;
		}else{
			fx = fx - xf;
		}
		
		if (y > 0) {
			fy = fy + yf;
		}else{
			fy = fy - yf;
		}
		
		if (z > 0) {
			fz = fz + zf;
		}else{
			fz = fz - zf;
		}
		
		if (p < g.Length - 1){
			p ++;
		}else{
			p = 0;
		}
	}
}

keeps giving me this error…

OverflowException: Number overflow.
CelestialGravity.Update () (at Assets/Physics/CelestialGravity.js:50)

so this is the only issue that remains with this script.

6

Your calculations are exceeding the maximum number of decimals Unity’s float values can have. Try using System.Double for your variables instead of float.

7

Could you give me a piece of code that uses this as an example?

8

I belive all you need to do is declair the non working float as follows

var {whatever} : system.double;

That should declair it as a system double, and if Diviner is correct, solve the problem

9 
var G : System.Double = 1.0;

Note the casing.

10

thx, it works wonderfully now.