Resetting a position

Question

Ive made a game where there are two states of play: Play (where objects are affected by gravity and are not kinematic) and Stop (where they are not, and a player can move them around).

By all means I can t$$anonymous$$nk of, t$$anonymous$$s following code should work, but it doesn;t.

void LateUpdate () {

 if (playScript.gamePlays == false) { //if game is not playing
     if (playedLastFrame == true) { // but if game did play last frame
         transform.position = new Vector3(initialTransform.position.x, initialTransform.position.y, initialTransform.position.z);
         transform.rotation = initialTransform.rotation;
         transform.localScale = initialTransform.localScale; 
     }
     playedLastFrame = false;
     rigidbody.isKinematic = true;
     rigidbody.useGravity = false;
 } else {   //if game currently plays
     if (playedLastFrame == false) {   //if game last frame didn't play (so button was pressed)
         initialTransform.position = t$$anonymous$$s.gameObject.transform.position;
         initialTransform.rotation = t$$anonymous$$s.gameObject.transform.rotation;
     }   
     playedLastFrame = true;
     rigidbody.isKinematic = false;
     rigidbody.useGravity = true;

 }

}

}

In the playScript, there is a button that when pressed on (in the ONGUI function) sets gamePlays to true or false. At that point it should check wether or not the game was playing in the last frame. If it was playing in the last frame and isn't now,it should set the transform of the item to its initialTransform. But it doesn't. Why?

Answer 1

You don't really say what it is doing incorrectly, but if I had to guess, I'd suspect your problem is your initialTransform. Since you can't access the constructor for Transform, I imagine you are assigning it some other Transform. Transform is a reference type, so if initialTransform == transform, then transform.position = initialTransform.position is meaningless. You'll need to keep your position, rotation and scale as individual variables.

There's a bunch not included in the question that could be wrong with your variable declarations and their initial values as well.

You don't need t$$anonymous$$s.gameObject. since transform is a publicly accessible member of MonoBehaviour w$$anonymous$$ch your class should inherit if you want LateUpdate to even be called.

If you were to simplify your variables and functions into somet$$anonymous$$ng more legible, it would be much easier to follow what is happening and what is wrong.

Keep it simple

Why are you calling all t$$anonymous$$s every frame and having to check your button state the last frame when you could just have your button call the function on the object(s) when it is pushed?

TogglePhysics.cs

using UnityEngine;

public class TogglePhysics : MonoBehaviour {
    public Transform target;

 Vector3 pausePosition;
 Vector3 pauseScale;
 Quaternion pauseRotation;
 string text;

 void Start() {
    if(target) {
        pausePosition = target.position;
        pauseScale = target.localScale;
        pauseRotation = target.rotation;
    }
    ButtonOn();
 }

 void OnGUI() {
     if(GUI.Button(new Rect(10, 10, 150, 100), text)) {
         if(text == "ON") ButtonOff();
         else ButtonOn();
     }
 }

 void ButtonOff() {
     text = "OFF";
     if(target) {
         if(target.rigidbody) {
             target.rigidbody.isKinematic = true;
             target.rigidbody.useGravity = false;
         }
         pausePosition = target.position;
         pauseScale = target.localScale;
         pausesRotation = target.rotation;
     }
 }

 void ButtonOn() {
     text = "ON";
     if(target) {
         if(target.rigidbody) {
             target.rigidbody.isKinematic = false;
             target.rigidbody.useGravity = true;
         }
         target.position = pausePosition;
         target.localScale = pauseScale;
         target.rotation = pauseRotation;
     }
 }

From the object perspective

To do it the way you have it would work like:

ToggleButton.cs

using UnityEngine;

public class ToggleButton: MonoBehaviour {
    string text;
    public static bool ButtonOn;

 void Start() {
    ButtonOn();
 }

 void OnGUI() {
     if(GUI.Button(new Rect(10, 10, 150, 100), text)) {
         if(ButtonOn) ButtonOff();
         else ButtonOn();
     }
 }

 void ButtonOff() {
     text = "OFF";
     ButtonOn = false;
 }

 void ButtonOn() {
     text = "ON";
     ButtonOn = true;
 }

TogglePhysics.cs

using UnityEngine;

[RequireComponent (typeof (Rigidbody))]
public class TogglePhysics : MonoBehaviour {
    Vector3 pausePosition;
    Vector3 pauseScale;
    Quaternion pauseRotation;
    bool currentState;

 void Start() { //Initialize
    pausePosition = transform.position;
    pauseScale = transform.localScale;
    pauseRotation = transform.rotation;
    TurnOn();
 }

 void LateUpdate() {
     if(currentState == ToggleButton.ButtonOn) return; //we're good

     if(ToggleButton.ButtonOn) TurnOn();
     else TurnOff();
 }

 void TurnOn() {
     rigidbody.isKinematic = false;
     rigidbody.useGravity = true;
     transform.position = pausePosition;
     transform.localScale = pauseScale;
     transform.rotation = pauseRotation;
     currentState = true;
 }

 void TurnOff() {
     rigidbody.isKinematic = true;
     rigidbody.useGravity = false;
     pausePosition = transform.position;
     pauseScale = transform.localScale;
     pausesRotation = transform.rotation;
     currentState = false;
 }

If you knew not$$anonymous$$ng else was changing your booleans, you could even simplify boolean assignments to be rigidbody.isKinematic = !rigidbody.isKinematic; and the like.

Answer 2

Answer by Jordi · Oct 19, 2010 at 07:27 AM

I see what you mean. I'll wrestle through the code, try it out t$$anonymous$$s afternoon and update you on the progress. Thanks in advance ^^

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Bravini · Oct 19, 2010 at 04:18 PM 0

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please use comments instead of answers for replies :]

Answer 3

Answer by Bravini · Oct 18, 2010 at 08:51 PM

Skovacs code is flawless except that if I got the question right, Jordi wants to return all the transforms to initial position when paused, so the snippet

void TurnOff() {

   rigidbody.isKinematic = true;
   rigidbody.useGravity = false;
   pausePosition = transform.position;
   pauseScale = transform.localScale;
   pausesRotation = transform.rotation;
   currentState = false;
}

 <p>should go as</p>

void TurnOff() {

   rigidbody.isKinematic = true;
   rigidbody.useGravity = false;
   currentState = false;
}

having the pause vars always setted to the starting position.

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Answer 4

Answer by Jordi · Oct 21, 2010 at 06:53 PM

It works for just one snag: it didn't recognise the difference between bool ButtonOff and function ButtonOff(), so just had to rename those. Awesome! Now off to making mouseOver and mouseExit GUI elements ^^

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Resetting a position

4 Replies

Keep it simple

From the object perspective

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