2D Problem

Unity Engine
1

Hi everyone i’m making a tutorinal for some of my friends about basics in unity.
I made a simple 2D Ball rolling game, the problem is when ball sometimes hit some obstical it rolles off platforme.Can someone help me with a script to just stay on course.Thank you if you understand.

// speed of the ball
var speed = 5.0;
var radius = 5.0;
private var velocity : Vector3 = Vector3.zero;

function Start(){
	transform.localScale = Vector3.one * radius * 2;
	var hit : RaycastHit;
	if(Physics.Linecast(transform.position, transform.position - Vector3.up * 1000, hit)){
		transform.position = hit.point + Vector3.up * radius;
	}
	// add a rigidbody if we dont have one.
	if(!rigidbody)
		gameObject.AddComponent(Rigidbody);
	// set the mass according to the radius.
	rigidbody.mass = 100 * radius;
}

function FixedUpdate () {
	// let see if our body is on the ground.
	var hit : RaycastHit;
	var isGrounded = Physics.Raycast(transform.position, -Vector3.up, hit, radius * 1.5);
	
	// base movement off of the camera, not the object.
	// reset the camera's X to zero, so that it is always looking horizontally.
	var x = Camera.main.transform.localEulerAngles.x;
	Camera.main.transform.localEulerAngles.x = 0;
	
	// now collect the movement stuff This is generic direction.
	var direction = Vector3(Input.GetAxis("Horizontal"),0);
	
	// prevent the ball from moving faster diagnally
	if(direction.magnitude > 1.0) direction.Normalize();
	
	// If we are grounded, then lets see if we want to jump.
	if(isGrounded  Input.GetKeyDown(KeyCode.Space))
		rigidbody.AddForce(Vector3.up * rigidbody.mass * 350);
	
	// if we arent pressing anything, dont mess with the physics.
	if(direction.magnitude > 0){
		// convert isGrounded into something we can use
		var modifier = isGrounded ? 3.0 : 0.5;
		// lets set the direction according to the camera now.
		direction = Camera.main.transform.TransformDirection(direction) * speed * 2;
		// lets take the downward velocity from the current so that we dont get wierd physics results
		direction.y = rigidbody.velocity.y;
		
		// Now, lets keep track of a velocity.
		// This will let the ball move while we are not pressing anything.
		rigidbody.velocity = Vector3.Lerp(rigidbody.velocity, direction, modifier * Time.deltaTime);
		// Now, lets break the rotation out from the movement.
		var rotation = Vector3(rigidbody.velocity.z,0,-rigidbody.velocity.x) * 1;
		
		
		// Lets add some spin to make the ball move better
		rigidbody.angularVelocity = Vector3.Lerp(rigidbody.angularVelocity, rotation, modifier * Time.deltaTime);
	}
	
	// return the camera's x rotation.
	Camera.main.transform.localEulerAngles.x = x;
}
2

maybe rigidbody constraints would help,
“Constraints: Restrictions on the Rigidbody’s motion”

3

Thank you it works.Thats just what i needed. :smile: