2D Movement with Position Array

Unity Engine
1

Hey!
I got a file with some data that contains velocity, time and position values for an object. (acc_x, acc_y, t, pos_x, pos_y, so this is 2d!)
What I need to do is move the object smoothly according to the data.
i tried to move the object by checking the time that has passed and comparing it to the data.
then i count up the index of the position arrays, so i know where the object has to be. but when i use lerp, it still doens’t move smoothly…
Maybe I’m doing it way too difficult and complicated, so please let me know if you know of anything that i can use, so it’s moving smoothly and still accurate! let me know if you want to read the code.

thank you!

2

Sounds similar to how I’d approach the problem. Show us the code you have (in code tags), you may be using something a little bit wrongly.

3

So this is my code. I set the multiplier to 10 because the values were too small to work with. i was playing around with the speed and set it to 0.5 but also tried 200. didnt seem to work…

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

public class jsonthingy : MonoBehaviour
{
    public int multiplier;

    public float timepassed;

    public animationData _animData;
    public int xIndex , yIndex , tIndex;
    string path;
    string jsonString;
    bool dataLoaded = false;

    public GameObject Person;
    int tempInt = 0;


  
    void Update()
    {
        timepassed = timepassed + Time.deltaTime;
      //  Debug.Log(timepassed);
        if (dataLoaded==false)
        {
            LoadData();
        }


        CheckTime(); // and move

    }

    //Lerp
    public float speed = 10f;
  
        //moving the person/wagon smoothly
    void LerpWagon()
    {
        Vector2 posA = new Vector2(_animData.x[tempInt - 1]*multiplier, _animData.y[tempInt - 1]*multiplier);
        Vector2 posB = new Vector2(_animData.x[tempInt]*multiplier, _animData.y[tempInt]*multiplier);

        Person.transform.position = Vector2.Lerp(posA, posB, speed);
    }

    void CheckTime()
    {
        if (tempInt < 75 && timepassed >= _animData.t[tempInt]*multiplier)
        {
          

            tempInt = tempInt + 1;
            LerpWagon();
        }
        else if(tempInt>=75)
        {
            Debug.Log("Reached end of Array");
            //moving person to right
            Person.transform.position += transform.right * 10f * Time.deltaTime;
        }

       
    }

    void LoadData()
    {
        path = Application.streamingAssetsPath + "/animation.json";
        jsonString = File.ReadAllText(path);
        animationData _animationData = JsonUtility.FromJson<animationData>(jsonString);
        for (int i = 0; i < 10; i++)
        {
            Debug.Log(_animationData.t[i]);
        }
        dataLoaded = true;

        // put it in variables
        _animData.t = _animationData.t;
        _animData.x = _animationData.x;
        _animData.y = _animationData.y;
        _animData.acc_x = _animationData.acc_x;
        _animData.acc_y = _animationData.acc_y;
    }
}


[System.Serializable]
public class animationData
{
    public float[] acc_x;
    public float[] acc_y;
    public float[] angle;
    public float[] t;
    public float[] x;
    public float[] y;
}
4

Little things that aren’t the main problem:

  1. You could use _animData directly on line 72, and then you wouldn’t need lines 80-84.
  2. It’s easier to read code if you use naming conventions in line with other code/communities, e.g. the Unity code base. Specifically, UpperCaseNames for class names, like AnimationData.

Your actual problem here: line 46. Lerp is something that a lot of people misunderstand, particularly the third parameter. You’re currently sending it a value of 10 all the time. You need to give it a number between 0 and 1. For 0 it will return posA, for 1 it will return posB, 0.5 will return a value halfway in between, etc. I think you want to use timepassed / _animData.t[tempInt] for that. (and I don’t think you want multiplier to affect that value, either there or on line 51)