koobas.hobune.stream
Universe function on gravity script not working
So recently I had the craving to try and create world scapes revolving around gravitational pull, so I stumbled upon this youtube video (https://www.youtube.com/watch?v=7axImc1sxa0&t=281s) that did a great job explaining everything for me and gave me a sample code: using System.Collections; using System.Collections.Generic; using System.Collections.Specialized; using UnityEngine;
public class PlanetBody : MonoBehaviour
{
public float mass;
public float radius;
public Vector3 initialVelocity;
Vector3 currentVelocity;
void Awake ()
{
currentVelocity = initialVelocity;
}
public void UpdateVelocity(PlanetBody[] allBodies, float timeStep)
{
foreach (var otherBody in allBodies)
{
if (otherBody != this)
{
float sqrDst = (otherBody.GetComponent<Rigidbody>().position - GetComponent<Rigidbody>().position).sqrMagnitude;
Vector3 forceDir = (otherBody.GetComponent<Rigidbody>().position - GetComponent<Rigidbody>().position).normalized;
Vector3 force = forceDir * Universe.gravitationalConstant * mass * otherBody.mass / sqrDst;
Vector3 acceleration = force / mass;
currentVelocity += acceleration * timeStep;
}
}
}
public void UpdatePosition (float timeStep)
{
GetComponent<Rigidbody>().position += currentVelocity * timeStep;
}
}
Now this was all well and good, until I attached it to a sphere (or any other object) and unity kept saying that Universe was used in the wrong context.
Could anybody tell me the right context or how to fix this issue? Thanks in advance
You can replace Universe.gravitationalConstant with 6.67408e-11f.
@andrew-lukasik - Your solution seems to have worked (I can't believe I didn't think to search up the universal gravitational constant!), but I'm quite lost on what to do revolving a second bit of code with similar issues:
public class NBodySimulation : $$anonymous$$onoBehaviour
{
PlanetBody[] bodies;
void Awake ()
{
bodies = FindObjectsOfType<PlanetBody>();
Time.fixedDeltaTime = Universe.physicsTimeStep;
}
void FixedUpdate()
{
for (int i = 0; i < bodies.Length; i++)
{
bodies[i].UpdateVelocity(Universe.physicsTimeStep);
}
for (int i = 0; i < bodies.Length; i++)
{
bodies[i].UpdatePosition(Universe.physicsTimeStep);
}
}
}
I have pretty much no idea of what to change Universe to in this code, so if you may have an answer, that'd be a lifesaver.
Again, thanks so much for the previous answer!
$$anonymous$$ake sure THIS file/class is among your project files
And then replace 6.67408e-11f with Universe.gravitationalConstant back again (since it's an arbitrary value there)
Alternatively:
public class NBodySimulation : $$anonymous$$onoBehaviour
{
[SerializeField] float _physicsTimeStep = 0.01f;
PlanetBody[] bodies;
void Awake ()
{
bodies = FindObjectsOfType<PlanetBody>();
Time.fixedDeltaTime = _physicsTimeStep;
}
void FixedUpdate ()
{
for( int i=0 ; i<bodies.Length ; i++ )
{
bodies[i].UpdateVelocity( Time.fixedDeltaTime );
}
for( int i=0 ; i<bodies.Length ; i++ )
{
bodies[i].UpdatePosition( Time.fixedDeltaTime );
}
}
}
