Vehicle speed up / slow down

[anon_37883278]

I made myself some script, which moves my Vehicle (riggid body) acros a surface. Just forward back turning.

var speed = 10;
var turnSpeed = 30;


function Update () {
	
	print ("current speed = " + speed);

	if (Input.GetKey ("up"))
	{
		transform.Translate(Vector3.forward * Time.deltaTime * speed);
		//transform.Rotate(Time.deltaTime * -12, 0, 0, Space.World);
		//transform.Rotate(Vector3.up * 50 * Time.deltaTime,Space.World);
	}
	 
	 if (Input.GetKey ("down"))
	{
		transform.Translate(Vector3.forward * Time.deltaTime * speed * -1);
		//transform.Rotate(Time.deltaTime * 12, 0, 0, Space.World);
		//transform.Rotate(Vector3.down * 50 * Time.deltaTime,Space.World);
	}

	if (Input.GetKey ("left"))
	{
		//transform.Rotate(0, Time.deltaTime * 16, 0);
		transform.Rotate(0, Time.deltaTime * turnSpeed * -1, 0, Space.Self);
		//transform.Rotate(Vector3.left * 50 * Time.deltaTime,Space.World);
	}

	if (Input.GetKey ("right")) 
	{
		transform.Rotate(0, Time.deltaTime * turnSpeed, 0, Space.Self);
		//transform.Rotate(Vector3.right * 50 * Time.deltaTime,Space.World);
	} 
}

My Question: How could i make the speed slowly buld up as i hold the button. And fall off over 2 seconds a i release the button.

[Ashkan_gc]

simply use the dynamic friction propetry of the physics material to slow down the movement of you rigidbody

[anon_37883278]

Yes Thank’s ill try it. But it’S not really wat i am up to: A “real” engine builds up speed. I want it not start/stop at once.

Is there a way to hold the Button -Increase a variable, release and the var sinks back to zero ?

[sebako]

I think you need something like this:

// higher movespeed with w and up key
			if(Input.GetKey("w") || Input.GetKey("up"))
			{
				if(speed <= maxSpeed)
					speed += 1;
				else
					speed = maxSpeed;
			}
			// lower movespeed with s and down key
			else if(Input.GetKey("s") || Input.GetKey("down"))
			{
				if(speed >= minSpeed)
					speed -= 3;
			}
			// lower movespeed if no key is pressed
			else if(!Input.GetKey("w") || !Input.GetKey("up"))
			{
				if(speed >= 0)
					speed -= 2;
			}

rgds

zem

[Troy-Dawson]

Update() is for per-frame things, but the engine uses FixedUpdate() for physics stuff.

Physics generally run better with a fixed update independent of the framerate. I run my scenes at 500hz physics currently.

Unity also has the rigidbody component where you can apply forces and torques to you objects. This is a good API to learn since it’s the best way to do this stuff.

Unity - Manual: Rigidbody component reference

[anon_35829778]

you should set up a max and min speed. where max speed could be 10 or 100. from this you simply would do this.

var Speed = 0; 
var minSpeed : float= 0; 
var maxSpeed : float = 10; 
var Accel = maxSpeed / .4; //change this to set up how much you want to speed up and down.

what this does is adds your accel to the speed by what you specify. check my math though im not very good at it. i basicly figured this out by playing with differnt settings.

after you get this set up your speed should look somethig like this.

if(Input.GetButton("Acellerate")){  
Speed = Accel + Mathf.Clamp(Speed, minSpeed, maxSpeed - Accel); 
} 
 
if (Input.GetButton("Decellerate")){ 
Speed = -Accel + Mathf.Clamp(Speed, minSpeed +Accel, maxSpeed );} 

if(("Acellerate")){ 
   rigidbody.velocity = transform.forward * Time.deltaTime * Speed; //Apply velocity in Update()

this should help you out i cut out some things and changed them from my original script to make more sence to you in your project. i would not sugest copy and pasteing it as i am probly useing differnt var’s and differnt key names. but this should be what your looking for. its a start. its also rigid body dependent so your going to need a rigid body controler on your mesh.
also you should be aware that this code doesnt really decellerate properly it stops you abruptly. i am working on this as i have yet to get it working properly. too busy doing what im good at… modeling.
but i will be revisting this script soon.

[anon_37883278]

Thank you for the help.

First I tested the script from zemog86
this is my setup so you have a engine script i separated it from a navigation script for rotation

var speed = 0;
var maxSpeed = 200;
var minSpeed = -20;

function Update () {

print ("Actual Speed: " + speed);

// higher movespeed with w and up key
         if(Input.GetKey("up"))
         {
            if(speed <= maxSpeed)
               speed += 1;
            else
               speed = maxSpeed;
         }
         // lower movespeed with s and down key
         else if(Input.GetKey("down"))
         {
            if(speed >= minSpeed)
               speed -= 3;
         }
         // lower movespeed if no key is pressed
         else if(!Input.GetKey("up"))
         {
            if(speed >= minSpeed)
               speed -= 2;
         } 


	transform.Translate(Vector3.forward * Time.deltaTime * speed /10);

}

Works ok, only Problem is: if you stop the aceleration goes to -1 or -2, so you move a little backwards

Next i tried your script orindoomhammer
I gues i did something wrong, this is my setup

var Speed = 0;
var minSpeed : float= 0;
var maxSpeed : float = 100;
var Accel = maxSpeed / .4;
//change this to set up how much you want to speed up and down. 


function Update () {
	
print ("Actual Speed: " + Speed);
	
	if(Input.GetButton("Acellerate")){ 
	Speed = Accel + Mathf.Clamp(Speed, minSpeed, maxSpeed - Accel);
	}
 
	if (Input.GetButton("Decellerate")){
	Speed = -Accel + Mathf.Clamp(Speed, minSpeed +Accel, maxSpeed );}

	if(("Acellerate")){
	rigidbody.velocity = transform.forward * Time.deltaTime * Speed;
	//Apply velocity in Update()
	}
}

Because when you hit the Button it just jumps to maxspeed and keeps it up. It does not acellerate and not decellerate if you release the Button.

Thanks a lot, lots of stuff to keep me um experimenting on

[sebako]

change this:

var Accel = maxSpeed / .4;

to this:

var Accel = 1.5;

play around with the number until you find one that is fine for you.

best regards

zemog

[anon_35829778]

told you it would be buggy. its my first script. the reason i have it set to /4 on my script is so you can scale the speed of each ship just by setting a max speed. workd pretty slick on my main code. but still has some bugs to work out.

[anon_37883278]

Thanks i inserted an else condition:

var Speed = 0;
var minSpeed : float= 0;
var maxSpeed : float = 150;
var Accel = 3;
var decel = 0.1;

//var Accel = maxSpeed / .4;
//change this to set up how much you want to speed up and down. 


function Update () {
	
print ("Actual Speed: " + Speed);
	
	if(Input.GetButton("Acellerate")){ 
		Speed = Accel + Mathf.Clamp(Speed, minSpeed, maxSpeed - Accel);
		}
	
	else {
		Speed = -decel + Mathf.Clamp(Speed, minSpeed +Accel, maxSpeed );
		}
	
	if (Input.GetButton("Decellerate")){
	Speed = -Accel + Mathf.Clamp(Speed, minSpeed +Accel, maxSpeed );
	}

	if(("Acellerate")){
	rigidbody.velocity = transform.forward * Time.deltaTime * Speed;
	//Apply velocity in Update()
	}
}

now you can step on the gas. release and it will slow down and you even have a handbreak

[anon_35829778]

yah my code is more for space ships and stuff, but looks like its fixed for you.

[anon_5443197]

I experienced a problem of accelearting rigidbody as a bug, may appear interesting for you (note that I’m writing it on the fly, probaably won’t work but get the main idea):

var maxSpeed = 10.0;
var accelerationForce = 1.0;

function Update ()
{
   if(Input.GetKey("Accelerate"){
   {
      if(rigidbody.velocity >= maxVelocity)
         rigidbody.velocity = maxVelocity;
      else
         rigidbody.AddForce(accelerationForce);
   }
}

[a170982]

Got for turning back or reverse?