Creating objects which are facing center of a sphere

Question

I´m making a game with planets as terrain and I want to spawn random trees by script. With my script trees spawn randomly on the sphere but their all in one rotation.

I´ve tried a lot of ways to make the spawn like in this picture : alt text

My script so far :`using UnityEngine; using System.Collections;

public class TreeSpawer : MonoBehaviour {

 public float TreeNumber;
 public GameObject tree;
 public float PlanetRadius;
 public GameObject PlanetOrigin;


 void Start () {
 
     for(int i=0; i<TreeNumber;i++)    {
         Vector3 origin = PlanetOrigin.gameObject.transform.position;
         Vector3 onPlanet = Random.onUnitSphere * PlanetRadius;
         Vector3 onYaxis = new Vector3(0,PlanetRadius,0);
         var Rotation = Vector3.Angle(;
         Instantiate(tree, onPlanet, "Rotation");
     }       
 }
 
 // Update is called once per frame
 void Update () {
 
 }

} ` Can you tell me how i get this done ? :) Thank you

TheSakuron

Answer 1

A simple way to do this would be to use Transform.LookAt http://docs.unity3d.com/ScriptReference/Transform.LookAt.html

Something like

 transform.LookAt(PlanetOrigin.transform.position);

will cause the z vector of the trees to be towards the the center of a sphere

However depending on how you modeled the trees, the forward vector might be coming out of the top, the bottom, or a side. If all your trees will need to have their rotation adjusted by the same amount then use Quaternion*Quaternion to adjust the rotation, i.e. the following will adjust the rotation 90 degrees along the x axis

 transform.rotation=transfrom.rotation*Quaternion.Euler(90, 0, 0);

So your code can look something like

 public float TreeNumber;
 public GameObject tree;
 public float PlanetRadius;
 public GameObject PlanetOrigin;
 
  
 void Start () { 
     for(int i=0; i<TreeNumber;i++)    {
         Vector3 origin = PlanetOrigin.gameObject.transform.position;
         Vector3 onPlanet = Random.onUnitSphere * PlanetRadius;
 
         GameObject newGO=Instantiate(tree, onPlanet, Quaternion.identity) as GameObject;
         newGO.LookAt(PlanetOrigin.transform.position);
         newGO.transform.rotation=newGO.transform.rotation*Quaternion.Euler(90, 0, 0);
     }       
 }

Creating objects which are facing center of a sphere

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