Rotating a Sphere While Moving

Unity Engine
1

Hello, it’s me again. I’ve been trying to figure out how to rotate a sphere when moving (think Marble Blast) Looking around I can’t seem to find anything and nothing I try seems to work.

Sorry for all the newbie questions :slight_smile:

2

To figure out how much to roll a ball based on the distance traveled you calculate:

rotation = distance / radius

So you can then apply that to your ball like this:

float rotation = ((transform.position - oldPos).magnitude / ballRadius;


// Now to apply it
transform.RotateAround(transform.right, rotation);

Note that this code assumes that you already rotated your ball to face the direction it’s moving in, like with a normal agent.

Then it just rotates to match the distance traveled.

Hope that helps!
-Jeremy

1 Like
3

I browsed around the Wiki a bit a found this script:

// These variables are for adjusting in the inspector how the object behaves
var maxSpeed = 7.000;
var force = 8.000;
var jumpSpeed = 5.000;

// These variables are there for use by the script and don't need to be edited
private var state = 0;
private var grounded = false;
private var jumpLimit = 0;

// Don't let the Physics Engine rotate this physics object so it doesn't fall over when running
function Awake ()
{
    rigidbody.freezeRotation = false;
}

// This part detects whether or not the object is grounded and stores it in a variable
function OnCollisionEnter ()
{
    state ++;
    if(state > 0)
    {
        grounded = true;
    }
}


function OnCollisionExit ()
{
state --;
    if(state < 1)
    {
        grounded = false;
        state = 0;
    }
}

// This is called every physics frame
function FixedUpdate ()
{


    // Get the input and set variables for it
    jump = Input.GetButtonDown ("Jump");
    horizontal = Input.GetAxis("Horizontal");
    vertical = Input.GetAxis("Vertical");

    // Set the movement input to be the force to apply to the player every frame
    horizontal *= force;
    vertical *= force;

    // If the object is grounded and isn't moving at the max speed or higher apply force to move it
    if(rigidbody.velocity.magnitude < maxSpeed  grounded == true)
    {
        rigidbody.AddForce (transform.rotation * Vector3.forward * vertical);
        rigidbody.AddForce (transform.rotation * Vector3.right * horizontal);
    }

    // This part is for jumping. I only let jump force be applied every 10 physics frames so
    // the player can't somehow get a huge velocity due to multiple jumps in a very short time
    if(jumpLimit < 10) jumpLimit ++;

    if(jump  grounded == true  jumpLimit >= 10)
    {
        rigidbody.velocity.y += jumpSpeed;
        jumpLimit = 0;
    }
 }

It works great except that while holding down the W key the ball rolls back and forth. What would I have to do to get the ball to roll forward in a straight line?

4

Any news?

5

Bump, since i could not find any solution for this either.

EDIT: Found it!

public var force:float = 1.0;

function FixedUpdate () {
	var dir : Vector3 = Vector3.zero;
	
	dir.x = Input.GetAxis("Horizontal");
	dir.z = Input.GetAxis("Vertical");
	
	rigidbody.AddForce(dir * force);
}