Rigidbody and Gravity (Jumping)

Everything is working almost perfectly. The one problem I'm having is the way the jumping looks.
Basically, if I hold down the Jump key, the jump looks right. But if I hold it and release it, I fall much faster than it looks like I should. Like gravity snaps into play the instant I take my finger off the jump key.
Take a look at the code.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Movement : MonoBehaviour {
5.  
6.     public float speed = 6.0f;
7.     public float jumpSpeed = 8.0f;
8.     private bool jump = false;
9.     public float gravity = 10.0f;
10.  
11.     Vector3 moveDir = new Vector3();
12.     public Rigidbody rb;
13.  
14.     // Use this for initialization
15.     void Start () {
16.        
17.     }
18.    
19.     // Update is called once per frame
20.     void Update () {
21.         Move ();
22.     }
23.  
24.     void Move(){
25.         moveDir = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
26.         moveDir = transform.TransformDirection(moveDir);
27.         moveDir = moveDir * speed;
28.         if (Input.GetButton ("Jump")){
29.             moveDir.y = jumpSpeed;
30.         }
31.         moveDir.y -= gravity * Time.deltaTime;
32.         rb.MovePosition(transform.position + moveDir * Time.deltaTime);
33.     }
34. }

Any tips or pointers are welcome!

 

You are applying the jump speed only when button is pressed... but, why to code gravity by yourself? Consider using the standard Unity physics engine.

http://unity3d.com/learn/tutorials/modules/beginner/physics

 

That's actually a much better idea. Thanks for the link too! It's very helpful.