Resolved Move object inside another rotating object

Hi guys,

I would like to move an object within a rotating object. I would like the child object in its movement to consider the rotation of the father.

As you can see in the video the red cube goes back and forth but in the same point, I would like it to rotate (remaining between the two white cubes as at the beginning)

To move the red cube I created this script:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class DinDong : MonoBehaviour
6. {
7.     public Transform dad; //yellow sphare
8.  
9.     private bool modeOut = true;
10.     private float currentLerpTime = 0f;
11.     private float targetTime = 1f;
12.     private float distance = 3f;
13.     private Vector3 startValue, endValue;
14.     private Vector3 value1, value2;
15.  
16.     private void Start()
17.     {
18.         value1 = startValue;
19.         value2 = (transform.position + (transform.position - dad.position).normalized * distance);
20.         ChangeValues();
21.     }
22.  
23.     private void ChangeValues()
24.     {
25.         if (modeOut)
26.         {
27.             startValue = value1;
28.             endValue = value2;
29.         }else
30.         {
31.             startValue = value2;
32.             endValue = value1;
33.         }
34.     }
35.  
36.     // Update is called once per frame
37.     void Update()
38.     {
39.  
40.         //increment timer once per frame
41.         currentLerpTime += Time.deltaTime;
42.         if (currentLerpTime > targetTime)
43.         {
44.             currentLerpTime = targetTime;
45.         }
46.  
47.         //lerp!
48.         float perc = currentLerpTime / targetTime;
49.         transform.position = Vector3.Lerp(startValue, endValue, perc);
50.  
51.  
52.         if (currentLerpTime == targetTime)
53.         {
54.             transform.position = endValue;
55.             //rest time
56.             currentLerpTime = 0f;
57.  
58.             modeOut = !modeOut;
59.             ChangeValues();
60.         }
61.  
62.  
63.     }
64.  
65. }
66.  

Any ideas to solve it?

 

Looks like you are capturing the positions in Start(), which only runs once. Is that your problem?

NOTE: Vector3 is a struct (value type) which means when you go:

Code (csharp):

1. foo = transform.position;

You made a copy that will never again change "just because" transform.position changes.

 

Hello Kurt-Dekker thanks,

You're right, but even if you recalculate it it won't change. I have to insert a change that takes into account the rotation of the father but I don't know how to do it

 

First naive attempt: call Start() from within Update(), see if that does it.

 

Also just noticed your line 52 compares floating point values for equality. Don't do that. I'll leave you to google the why, but basically use something like Mathf.Approximately() or do your own difference calculations.

 

Thanks, I fixed the check on the floats but I had already contained the problem with the previous check.

As for the rotation of the red cube, if I call start each update disappears as it goes away. I'm sure I need to do something with the rotation but I can't do it.

 

Anyone have any ideas? I'm on a blocked road

 

One things that comes to mind is to have a child empty game object inside the roating object. This empty object will rotate by default with it's parent and can serve as a reference point from which the object starts it's journey. You can have another similar object to reference the end position or you can calculate it like you did by adding the direction (empty object - parent)

Another thing is, I think you can take the direction from parent to the target position and multiply it by the rotation of the parent to get a rotated end pos

 

Hi DPunK thank you,

I had thought of a solution similar to 1 but I have to do it with about 300 objects and it seemed too expensive...

Could you explain better solution 2 instead please?

 

Ok guys actually it was enough to use local coordinates and everything works fine.
I ditched the problem for a while and when I got back I thought how stupid it was. If someone needed:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class DinDong : MonoBehaviour
6. {
7.     public Transform dad; //yellow sphare
8.  
9.     private bool modeOut = true;
10.     private float currentLerpTime = 0f;
11.     private float targetTime = 1f;
12.     private float distance = 0.5f;
13.     private Vector3 startValue, endValue;
14.     private Vector3 value1, value2;
15.  
16.  
17.     private void Start()
18.     {
19.         value1 = transform.localPosition;
20.         value2 = (transform.localPosition + (transform.localPosition - Vector3.zero).normalized * distance);
21.  
22.         ChangeValues();
23.     }
24.  
25.     private void ChangeValues()
26.     {
27.         if (modeOut)
28.         {
29.             startValue = value1;
30.             endValue = value2;
31.         }
32.         else
33.         {
34.             startValue = value2;
35.             endValue = value1;
36.         }
37.         transform.position = startValue;
38.     }
39.  
40.     // Update is called once per frame
41.     void Update()
42.     {
43.         //increment timer once per frame
44.         currentLerpTime += Time.deltaTime;
45.         if (currentLerpTime > targetTime)
46.         {
47.             currentLerpTime = targetTime;
48.         }
49.  
50.         float perc = currentLerpTime / targetTime;
51.         transform.localPosition = Vector3.Lerp(startValue, endValue, perc);
52.  
53.  
54.         if ( Mathf.Approximately(currentLerpTime, targetTime) )
55.         {
56.             transform.position = endValue;
57.  
58.             //rest time
59.             currentLerpTime = 0f;
60.  
61.             modeOut = !modeOut;
62.             ChangeValues();
63.         }
64.  
65.  
66.     }
67.  
68. }