Weird Jump Bug

So I am trying to make my game object jump. If I wait for a few seconds after my game starts, my code works just as intended. However, if i try to jump immediately after the game starts, I end up flying indefinitely, without falling.
This is my code...

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class PlayerController : MonoBehaviour
5. {
6. public GameObject player;
7. public float speed;
8. public float value = 0;
9. bool isGrounded = false;
10.  
11.  
12.      void OnCollisionEnter (Collision col)
13.      {
14.           if(col.gameObject.name == "Ground 1")
15.           {
16.           isGrounded = true;
17.           }
18.      }
19.  
20.      void OnCollisionExit (Collision col)
21.      {
22.           if(col.gameObject.name == "Ground 1")
23.           {
24.           isGrounded = false;
25.           }
26.      }
27.  
28.      void FixedUpdate ()
29.      {
30.      float moveHorizontal = Input.GetAxis ("Horizontal");
31.      float moveVertical = Input.GetAxis ("Vertical");
32.  
33.           if(isGrounded == true)
34.           {
35.                if (Input.GetKeyDown (KeyCode.Space))
36.                {value = 9.8f * 3.0f;}
37.                else {value = 0;}
38.           }
39.  
40.      Vector3 movement = new Vector3 (moveHorizontal, value , moveVertical);
41.      rigidbody.AddForce(movement * speed * Time.deltaTime);
42.      }
43. }

 

Can someone tell me what is going on and how I can fix my code?

 

I am guessing it has something to do with a FixedUpdate(). I undestand that adding forces works best with FixedUpdate(), but try experimenting with that.

 

I recreated your project, and I go flying up without hitting anything... pretty funny actually.

1) If value is set to a positive number in the inspector, all is lost... you aren't making sure value is zero when it starts.
2) You only set value = 0 if grounded = true, which if the player begins moving upward at the start of the scene, grounded will never be true and therefore value will never be a nonpositive number.

Do you understand?

 

I'm not sure I'm getting you... in line 8 i set value = 0; What can i change in my code to keep it from flying up.

 

You are only setting value to 0 if the player is on the ground. You're setting isGrounded = false; only when an OnCollisionExit() is executed, have you ever considered that that method may not get called like it's supposed to?

Change your code to check for collision with the ground, and if there's no collision set grounded to false. Add some debug.log calls so you can monitor the state of your variables in real time, notice any weird changes (a number is not zero when you're on the ground, for example).

I'm not going to write your script for you, though. That's no good for anyone.

 

Ok so I did this, and it no longer jumps forever, however if i try to jump immidiately after the game starts i jump twice as high

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. //Bug with player jumping infinately if player attemps to jump without hitting the ground first.
4. public class PlayerController : MonoBehaviour
5. {
6.     //Update is called once per frame
7.     public GameObject player;
8.     public float speed;
9.     public float value = 0;
10.     bool isGrounded = false;
11.  
12.  
13.     void OnCollisionEnter (Collision col)
14.     {
15.         if(col.gameObject.name == "Ground 1")
16.         {
17.             isGrounded = true;
18.             //print ("Collision");
19.             //Destroy(col.gameObject);
20.         }
21.     }
22.    
23.     void OnCollisionExit (Collision col)
24.     {
25.         if(col.gameObject.name == "Ground 1")
26.         {
27.             isGrounded = false;
28.         }
29.     }
30.    
31.     void FixedUpdate ()
32.     {
33.         float moveHorizontal = Input.GetAxis ("Horizontal");
34.         float moveVertical = Input.GetAxis ("Vertical");
35.  
36.         if(isGrounded == true)
37.         {
38.             if (Input.GetKeyDown (KeyCode.Space))
39.             {value = 9.8f * 3.0f;}
40.             else {value = 0;}
41.         }
42.         if(isGrounded == false)
43.         {
44.             value = 0;
45.         }
46.  
47.         Vector3 movement = new Vector3 (moveHorizontal, value , moveVertical);
48.         rigidbody.AddForce(movement * speed * Time.deltaTime);
49.     }
50. }

 

I think it's cycling through fixed update 2 times before the collision exit event is raised even though you are now only setting the value once you are actually adding force to the rigid body more than once this is because it still takes time for your body to move off of the platform and raised the on collision exit event.

Just think about it you'll get it

 

I tested it, and it thinks it is making an impact in the ground while in mid air at the start of the program. This only happens at the start if I try to jump Immediately after I start playing.

 

I dunno, lower the time scale and monitor your variables, something funky is happening and it's definitely something that you can fix.