Help-Use gravity only within a certain area

How could use gravity alone in an area of land , as if embers in a dome ?

 

Create a sphere gameobject and set its collider to isTrigger. This sphere is the area gravity exists.
On all your rigidbodies, set their "Use Gravity" to false.

Put this script on the sphere we made, and now you can walk into the sphere and get gravity.

Code (CSharp):

1. using UnityEngine;
2.  
3. public class ColliderGravity : MonoBehaviour
4. {
5.     public Vector3 gravity = Physics.gravity;
6.  
7.     void OnTriggerStay(Collider colliderInfo)
8.     {
9.         if(colliderInfo.attachedRigidbody != null)
10.         {
11.             colliderInfo.attachedRigidbody.AddForce(gravity);
12.         }
13.     }
14. }

 

thank testing tomorrow : D

 

Just out of curiosity wouldn't it be Mutch faster to place a game object in the middle and do a range check i

 

Im not sure, because then we would need to either put on every rigidbody that we want to be affected by said gravity a script that has a reference to the gameobject to be able to check the range, or we would need to reference all the rigidbodies on the gameobject and it would need to loop through them all every frame to check the range.

Where as with OnTriggerEnter, it isnt only more user friendly, but unity might be doing extra optimizing for us, and they may already have had the info being used for other calculations, and doing OnTriggerEnter is just us saying "pass that info to us too please". I'm not sure if that is how it works though =)

Profile it I guess ^^

 

So here is what i got first the code i used with Colliders

Spoiler: cube

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Cube : MonoBehaviour
5. {
6.     void OnCollisionEnter()
7.     {
8.         this.GetComponent<BoxCollider> ().enabled = false;
9.         this.GetComponent<Rigidbody> ().useGravity = false;
10.         this.GetComponent<Rigidbody> ().velocity = Vector3.zero;
11.         Main.count ++;
12.     }
13. }
14.  

Spoiler: spawn

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Spawn : MonoBehaviour
5. {
6.     private int size = 25; // 15625 rigid bodys
7.     void Start ()
8.     {
9.         for (int x = 0; x < size; x++)
10.         {
11.             for (int y = 0; y < size; y++)
12.             {
13.                 for (int z = 0; z < size; z++)
14.                 {
15.                         GameObject.Instantiate(Resources.Load("Cube"),new Vector3(x * 1.5f,y * 1.5f,z * 1.5f),Quaternion.AngleAxis(180,Vector3.zero));
16.                  
17.                 }
18.             }
19.         }
20.         Main.start = true;
21.     }
22. }

Spoiler: main

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Main : MonoBehaviour
5. {
6.     public static int  count = 0;
7.     public static bool start = false;
8.     private float time = 0;
9.  
10.     void Update ()
11.     {
12.         if (start == true)
13.         {
14.             time = Time.time;
15.             start = false;
16.         }
17.         if (count == 15625)//15625 from Spawn.cs
18.             Debug.Log (Time.time - time);
19.     }
20. }
21.  

the results are

3.88901
3.79381
3.79797
3.84071

now with using range

Spoiler: cube

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Cube : MonoBehaviour
5. {
6.     public bool collision = true;
7.  
8.     public void Collision()
9.     {
10.         collision = false;
11.         this.GetComponent<Rigidbody> ().useGravity = false;
12.         this.GetComponent<Rigidbody> ().velocity = Vector3.zero;
13.         Main.count ++;
14.     }
15. }
16.  

Spoiler: spawn

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Spawn : MonoBehaviour
5. {
6.     private int size = 25; // 15625 rigid bodys
7.     void Start ()
8.     {
9.         for (int x = 0; x < size; x++)
10.         {
11.             for (int y = 0; y < size; y++)
12.             {
13.                 for (int z = 0; z < size; z++)
14.                 {
15.                         NoGravityArea.cube_list.Add(Instantiate(Resources.Load("Cube"),new Vector3(x * 1.5f,y * 1.5f,z * 1.5f),Quaternion.AngleAxis(180,Vector3.zero)) as GameObject);
16.                 }
17.             }
18.         }
19.         Main.start = true;
20.     }
21. }
22.  

Spoiler: no gravity area

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using System.Collections.Generic;
4.  
5. public class NoGravityArea : MonoBehaviour {
6.  
7.     public static List<GameObject> cube_list = new List<GameObject>();
8.  
9.     void FixedUpdate ()
10.     {
11.         for (int i = 0; i < cube_list.Count; i ++)
12.         {
13.             if(cube_list[i].GetComponent<Cube>().collision == true &&
14.                Mathf.Sqrt
15.                (
16.                        ((cube_list[i].transform.position.x - this.transform.position.x) * (cube_list[i].transform.position.x - this.transform.position.x))
17.                     +
18.                     ((cube_list[i].transform.position.y - this.transform.position.y) * (cube_list[i].transform.position.y - this.transform.position.y))
19.                     +
20.                     ((cube_list[i].transform.position.z - this.transform.position.z) * (cube_list[i].transform.position.z - this.transform.position.z))
21.                 ) < 30)
22.             {
23.                 cube_list[i].GetComponent<Cube>().Collision();
24.             }
25.         }
26.     }
27. }
28.  

the results are (with FixedUpdate)

3.933629
3.938395
3.934564
3.945481

the results are (with Update) what is inacurate

3.816878
3.905328
3.90814
3.901522

so there is no mutch difference for me but you can optimize more thinks if you do it with range and not a collider

 

Might just be unneeded premature optimization though, as well as possibly more complex, harder to understand code compared to just OnTriggerStay.

 

I have a doubt

is possible that gravity fields (using the first code
of HiddenMonk) have different forces of gravity?
Field 1 gravity 0,9,0
FIELD 2 0, -9.0

 

Code (csharp):

1. public Vector3 gravity2 = new Vector3(0f, 9f, 0f);

 

Instead of doing gravity2 like pirs said. Just make a new sphere gameobject marked as isTrigger, put the ColliderGravity script on it, and in the inspector change the gravity from -9.81 to what ever u want.

This is the beauty of components =)