AddRelativeForce not working correctly

I am stuck on the code for couple of days but couldn't figure it out. Therefore I turned out to look the answer here but couldn't find any that match the requirement Hope some One might help

here is the code

Code (CSharp):

1.  /*  Part1
2.      *Step Horizontal Movement
3.      * Use to get left and right movement
4.      */
5.     if(Input.GetKey ("right")||Input.GetKey ("left")){
6.         moveDir.x = Input.GetAxis("Horizontal"); // get result of AD keys in X
7.     }
8.     rigidbody.velocity = moveDir * speed;
9.     /*Part2
10.      *Continuse Forward Movement
11.      */
12.     if (Input.GetKey(KeyCode.UpArrow) || Input.GetKey(KeyCode.W))
13.     {
14.         moveDir.z = Input.GetAxis("Vertical");
15.         rigidbody.AddRelativeForce(moveDir*50);
16.     }

I have a Cube with added rigidBody Component. When pressed left or right key the cube should move in that direction and when key is released it should stop Part one when run commenting part2 code runs correctly

the other movement that I am trying to achieve is the cube should move continuously.But the thing is when pressed up key it should increase the magnitude and when released it should maintain the magnitude and move constantly.This is also achieved successfull with the part2 code by commenting part1 code But when but run without commenting any of them part1 results are correct but part2 does not provide correct result which was obtained by commenting part1 code

Is there any other way to obtain the same reult

 

You are setting the velocity and adding force. That is bound to give problems.

 

So is there any other way to get the same result

 

Best to use AddRelativeForce for both, but check out the ForceMode parameter as this allows you to vary how the force acts.

http://docs.unity3d.com/ScriptReference/ForceMode.html

Changing the velocity directly is not recommended - http://docs.unity3d.com/ScriptReference/Rigidbody-velocity.html

 

This is what is used to implement using transform without rigidbody and gave pretty good result so I tried to get the same by using physic but all efforts were in vein

Code (CSharp):

1.    
2.  Vector3 moveDir = Vector3.zero;
3.         if(Input.GetKey ("right")||Input.GetKey ("left")){
4.             moveDir.x = Input.GetAxis("Horizontal"); // get result of AD keys in X
5.            
6.             if(ShipCurrentSpeed==0)
7.             {
8.                 moveDir.x *= 3f * Time.deltaTime;
9.                 //transform.position += moveDir * 3f * Time.deltaTime;
10.             }else if(ShipCurrentSpeed<=15)
11.             {
12.                 moveDir *= ShipCurrentSpeed * 2f * Time.deltaTime;
13.                 //transform.position += moveDir * ShipCurrentSpeed * 2f * Time.deltaTime;
14.             }else
15.             {
16.                 moveDir *= 20f * Time.deltaTime;
17.                 //transform.position += moveDir * 20f * Time.deltaTime;
18.             }
19.         }
20.     //Increase inSpeed
21.         if (Input.GetKey ("up") && (ShipCurrentSpeed < ShipTopSpeed)) {
22.             ShipCurrentSpeed = ShipCurrentSpeed + ShipAcceleration;
23.         }
24.         //Decrese the speed
25.         if (Input.GetKey ("down") && (ShipCurrentSpeed > RevShipTopSpeed)) {
26.             ShipCurrentSpeed = ShipCurrentSpeed - ShipDecceleration;
27.         }
28.         if (ShipCurrentSpeed < 0 || ShipCurrentSpeed == 0) {
29.             ShipCurrentSpeed = 0;
30.             move = Vector3.forward * ShipCurrentSpeed;
31.         }
32.         if (ShipCurrentSpeed > 0) {
33.             move = Vector3.forward * Time.deltaTime * ShipCurrentSpeed;
34.         }
35.         if(ShipCurrentSpeed > ShipTopSpeed)
36.         {
37.             ShipCurrentSpeed = ShipTopSpeed;
38.         }
39.  
40.         //Jump
41.         if (isGrounded) {
42.             amountToJump = 0;
43.                         // Jump
44.             if (Input.GetButtonDown("Jump")) {
45.                 amountToJump = jumpHeight;  
46.             }
47.         }
48.  
49.         amountToJump -= gravity * Time.deltaTime;
50.         MovementPlayer(amountToJump * Time.deltaTime,move.z,moveDir.x);
51.         //transform.Translate(move);

 

Code (csharp):

1.  
2. ShipCurrentSpeed = ShipCurrentSpeed + ShipAcceleration;
3.  

It is beter to make this time dependent:

Code (csharp):

1.  
2. ShipCurrentSpeed += Time.deltaTime * ShipAcceleration;
3.  

This code does nothing.

Code (csharp):

1.  
2. if (ShipCurrentSpeed < 0 || ShipCurrentSpeed == 0) {
3.           ShipCurrentSpeed = 0;
4.             move = Vector3.forward * ShipCurrentSpeed;
5.        }
6.  

If you want to move something, in my opinion it is best to use Vector3.MoveTowards or AddRelativeForce or adjust the velocity if you know how it works. You should keep this in Update or a fixed Update and not a seperate coroutine. It is easiest to use the ships rotation to determine the direction to give the force in..

Code (csharp):

1.  
2. move = Vector3.forward * Time.deltaTime * ShipCurrentSpeed;
3.  

Should be:

Code (csharp):

1.  
2. rigidbody.AddRelativeForce (Vector3.forward * ShipCurrentSpeed);
3.