Question Instantiate the road always rotate correctly based on the last road

The new spawn road does not align with the last road.
I spawn the new road based on the end point of the last road, the position is correct however the rotation seems not rotate correctly and i have no idea how to rotate it.


The script just take road pieces to choose randomly which to spawn next and update the last road.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class InstantiateTest: MonoBehaviour
6. {
7.     public GameObject LastObject;
8.     public GameObject[] ObjectToSpawn;
9.     //public Transform Location;
10.     // Start is called before the first frame update
11.     void Start()
12.     {
13.        
14.     }
15.  
16.     // Update is called once per frame
17.     void Update()
18.     {
19.         if (Input.GetKeyDown(KeyCode.T))
20.         {
21.             var targetLocation = LastObject.transform.Find("EndPoint").position;
22.  
23.             GameObject g = ObjectToSpawn[Random.Range(0, ObjectToSpawn.Length)];
24.  
25.             LastObject = Instantiate(g, targetLocation, Quaternion.identity);
26.         }
27.     }
28. }

 

Quaternion.identity basically means "use the default rotation". I dont know what the "correct" rotation for your usecase is. You can copy the rotation of LastObject by instead passing LastObject.transform.rotation. For anything else you need to define the rotation you consider "correct" and then apply it to the object, either by passing it to Instantiate or by editing its transform afterwards.

https://docs.unity3d.com/ScriptReference/Object.Instantiate.html
https://docs.unity3d.com/ScriptReference/Quaternion.html
(Be a bit careful with quaternions. Their values are called x, y, z and w. These do not in any reasonable way relate to euler angles and should never be manually edited. Always use the functions provided to achieve your goal.)

 

if the rotation is unknown (seems like those pieces have turns and angles that are hard to know?)

could place empty dummy transforms on each prefab, to mark correct Forward direction
(so could take rotation from that dummy object, or calculate from blue forward axis)

 

This approach is used in this file here:

https://github.com/tutsplus/3d-dung...r/src/Assets/Scripts/ModularWorldGenerator.cs

And you can get the whole repo to see it in operation.

It's for matching dungeons with door linkages, but same idea for roads.