Getting the speed of a gameobject

Question

How can i by using javscript get the speed of a gameobject? I cant use Rigidbody.velocity as the object is not a Rigidbody.

Answer 1

Best Answer

Answer by qJake · May 11, 2010 at 10:10 PM

I just wrote this now, I didn't test it or anything, but you can give it a try if you want. Just drop this into a file called Speed.cs and you can read the public "speed" variable from it to get the speed of the object.

using UnityEngine;

public class Speed : MonoBehaviour
{
    public float speed = 0;

 Vector3 lastPosition = Vector3.zero;

 void FixedUpdate()
 {
     speed = (transform.position - lastPosition).magnitude;
     lastPosition = transform.position;
 }

}

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Mattivc · May 12, 2010 at 01:17 PM 0

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I tryed this, but the output keep fluctuating betwene the actual speed value and zero.

qJake · May 12, 2010 at 09:25 PM 0

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I changed Update to FixedUpdate, try that.

jorjdboss · Jan 08, 2014 at 09:44 AM 0

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Its better to use a coroutine for this task. Please look at my answer.

Krynin · Mar 15, 2018 at 07:04 PM 0

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It may be a golden shovel award and noob question but how can I replace 2D text with the value from that script??

lwks Krynin · May 23, 2019 at 01:16 PM 0

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Well you should've probably created another question, but you'd have to make something like this

 using UnityEngine.UI;
 
 public Text screenText;
 public float value;
 
 void Start()
 {
 screenText.text = value.ToString();
 }

Pangamini · May 23, 2019 at 02:20 PM 1

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to get a real speed, you should do speed = (transform.position - lastPosition).magnitude / Time.fixedDeltaTime

Optionally, you can call it 'rawSpeed' and calculate some 'smoothSpeed' in Update() by using SmoothDamp()

Answer 2

Answer by jorjdboss · Feb 29, 2012 at 04:23 PM

Its hardly 8-9 lines of code. Please check out this link to my blog: http://fungamesprogrammer.blogspot.in/2012/02/calculate-velocity-of-non-rigidbodies.html

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FullHeartGames · Oct 02, 2016 at 08:10 PM 0

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I like this method alot!

MFKJ · Sep 11, 2018 at 04:49 AM 0

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Your and @qJake answer is not same!

Answer 3

Hey all I know this is an old thread but ive been wandering the internet for a few hours trying to find a solution and the closest I got was jorjdboss' response, however it still wasnt working but he was on the right track. Here is the code I modified for any lost puppy wandering the internet like i was (working in 2019.1.2f1). This responds the speed in km/h and rounds it to the nearest whole number and doesn't fluctuate between a value and zero like most of the solutions i was finding. Hope this helps someone.

 void Start()
     {
         StartCoroutine(CalcVelocity());
     }
 
     IEnumerator CalcVelocity()
     {
         while(Application.isPlaying)
         {
             lastPos = player.transform.position;
             yield return new WaitForFixedUpdate();
             movesSpeed = Mathf.RoundToInt(Vector3.Distance(player.transform.position,lastPos)/Time.fixedDeltaTime);
         }
         
     }

Answer 4

Answer by ankur30884_unclaimed · Jun 07, 2012 at 10:48 AM

calculate speed of object in KM/H

Vector3 lastPosition = Vector3.zero;

 void FixedUpdate()
 {
     dispSpeed = (((transform.position - lastPosition).magnitude) / Time.deltaTime) ;
     lastPosition = transform.position;
 }

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MichaelJT · Apr 06, 2015 at 04:20 PM 0

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Tested and it doesn't work.

Pangamini · May 23, 2019 at 02:21 PM 0

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yeah, use Time.fixedDeltaTIme in FixedUpdate()

Answer 5

Answer by davedev · May 11, 2010 at 02:34 PM

This might not be the best, official, easiest way, but in an effort to respond first, here's how I've done it one of my projects.

Basically, you get/save the loc from the previous update and then use the difference in distance and time since the previous update to calculate the time:

// determine the amount of time since last update

var curTime = Time.time;

var updateTime = curTime - lastUpdateTime;

// save old loc at beginning of your update loop

var oldLoc = transform.position;

// do something to change the loc on this update

var newLoc = transform.position;
var updateDistanceMeters = Vector3.Distance(newLoc, oldLoc);

// my results are in miles per hour 
var updateDistanceMiles = convertMetersToMiles(updateDistanceMeters);

var updateTimeHours = updateTime/60.0/60.0;
calculatedAircraftSpeed = (updateDistanceMiles)/(updateTimeHours);

// save the current time for use on the next update

lastUpdateTime = curTime;

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Mattivc · May 11, 2010 at 09:34 PM 0

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Im having trouble folowing this code, do any one have a suggestion for a more simple solution for this problem?

qJake · May 11, 2010 at 10:09 PM 0

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Getting the speed of a gameobject

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