Ball Addforce Acceleration Speed

Question

Hello, I am not too good with scripting in Unity and I have come across a few problems. I have tried for weeks to get it working but with no success.

Basically, I am trying to make a game where the player has to navigate a level using a wooden ball. They use the arrow keys to controll the rolling of the ball.

I have made a script using AddForce with Rigidbodies on my ball object but the ball rolls incredibly slow and takes ages to change direction.

I want to be able to have a fast acceleration and be able to change directions fast but still have a relatively low top speed.

Here is my script so far:

 function FixedUpdate () {
 
     if (Input.GetKey ("up")) 
         {
             rigidbody.AddForce (Vector3.forward * Time.deltaTime * 5, ForceMode.Acceleration);
         }
     
     
     if (Input.GetKey ("down")) 
         {
             rigidbody.AddForce (Vector3.forward * Time.deltaTime * 5, ForceMode.Acceleration);
         }
     
     
     if (Input.GetKey ("left")) 
         {
             rigidbody.AddForce (Vector3.left * Time.deltaTime * 5, ForceMode.Acceleration);
         }
         
         
 if (Input.GetKey ("right")) 
     {
         rigidbody.AddForce (Vector3.right * Time.deltaTime * 5, ForceMode.Acceleration);
     }

I really need help with getting this script to work how I have described. Any help would be greatly appreciated.

Answer 1

You're on the right track, except for some specifics-

If you use ForceMode.Acceleration, there will be virtually no top speed. It's basically emulating gravity!
There isn't really an inbuilt way to give a rigidbody a 'top speed' as such- you can, however, give it relatively high drag and low mass, and it will stop moving soon after you stop putting a force on it.
Is there any reason why you need to be using discrete inputs here? Why can't you use the Input.GetAxis("Horizontal/Vertical")? If you do something like that, you could fake out your drag to give a better response time, and still control the desired velocity.

This is how I would do it:

public float desiredSpeed; public float maximumDrag; public float forceConstant; void Update() { Vector3 forceDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical")); //This reduces drag when the player adds input, and makes it stop faster. rigidbody.drag = Mathf.Lerp(maximumDrag, 0, forceDirection.magnitude); // this reduces the amount of force that acts on the object if it is already // moving at speed. float forceMultiplier = Mathf.Clamp01((desiredSpeed - rigidbody.velocity.magnitude) / desiredSpeed); // now we actually perform the push Rigidbody.AddForce(forceDirection * (forceMultiplier * Time.deltaTime * forceConstant));

}

Ball Addforce Acceleration Speed

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