CODEWITHSUNDEEP
unity-game-engine
user42493
user42493

Reputation: 1103

How do we update the position of an object consistetly in update() method?

We're using Verlet method to move a Tukey. But it only moves it once and not continuously. The codes for updating the position of the Turkey is in Update() method so it should rune every frame. But It only runed once.

Futhermore, we put three times the codes for updating the position of the Turkey Line rendered object in the update method and it seems that the new position of the Turkey only move as if we moved it once. 

       using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GenerateTurkeys : MonoBehaviour
{

    public LineRenderer lineRenderer;
    // Start is called before the first frame update
    //int numberOfTurkeys;
    static int NUM_PARTICLES = 26;
    float fTimeStep;
    Vector3[] m_position = new Vector3[NUM_PARTICLES];
    Vector3[] m_acceleration = new Vector3[NUM_PARTICLES];
    Vector3[] m_oldPosition = new Vector3[NUM_PARTICLES];
    Vector3[] m_newPosition = new Vector3[NUM_PARTICLES];



    void Start()
    {
        lineRenderer = gameObject.GetComponent<LineRenderer>();

        lineRenderer.GetPositions(m_position);

        for(int i = 0; i < m_acceleration.Length; i++)
        {
            m_acceleration[i] = new Vector3(0.0f, -9.8f, 0.0f);
        }

        fTimeStep = 5.5f;


    }

    // Verlet integration step void ParticleSystem::
    void Verlet()
    {
        var random_direction = Random.Range(-1, 1);


            for (int i = 0; i < NUM_PARTICLES; i++)
            {
                m_newPosition[i] = 2 * m_position[i] - m_oldPosition[i] + m_acceleration[i] * fTimeStep * fTimeStep;
                m_oldPosition[i] = m_position[i];
                                }





    }



    // Update is called once per frame
    void FixedUpdate()
    {


        Verlet();
        lineRenderer.SetPositions(m_newPosition);

          }
}

Upvotes: 1

Views: 147

Answers (1)

Saeleas
Saeleas

Reputation: 548

First of all, FixedUpdate is used by the physics engine and updates differently from the normal Update method. Unless what you want to do has to be synced with the physics engine then you should use Update.

Secondly, your m_position vector is never updated, you call lineRenderer.getPositions only in the Start method. Because of this, your m_oldPositions will always be the same and the position won't change. To correct this your Verlet method should also update the m_position vector after the new position has been computed. Something like this:

    void Verlet()
    {
        var random_direction = Random.Range(-1, 1);


            for (int i = 0; i < NUM_PARTICLES; i++)
            {
                m_newPosition[i] = 2 * m_position[i] - m_oldPosition[i] + m_acceleration[i] * fTimeStep * fTimeStep;
                m_oldPosition[i] = m_position[i];
                m_position[i] = m_newPosition[i];
            }
}

Upvotes: 3

Related Questions