CODEWITHSUNDEEP
c#unity-game-engine
starter-kid
starter-kid

Reputation: 27

How to make an object move straight from random directions in Unity

I have a ball object in Unity 2D, this ball spawns at random positions on the screen and I want it to move in a 'straight-line depending on its direction e.g. if it's from the left it goes to the right or if it's from the top it goes to the bottom. I'm not sure if I should use transform.position/addforce/velocity to accomplish this and what direction I should use.

The following are what I have tried so far (I've tried using all directions)

ballRigidBody.AddForce(transform.up * speed);

ballRigidBody.velocity = Vector2.up * speed;

transform.position+=Vector2.up;

Upvotes: 1

Views: 1997

Answers (3)

Xuan Tien Pham
Xuan Tien Pham

Reputation: 1

In this case, you should first check which position the ball spawned at (Top, Bottom, Left, Right), then from that decide the movement direction. If the ball spawns at the bottom, the direction to go up should be Vector3.up for example.

After you get the force, you can use rigidBody.AddForce(direction * speed); to move the ball.

Upvotes: 0

Daniel M
Daniel M

Reputation: 766

In Unity3D transform.forward is the go to variable when you want to move forward.
In Unity2D transform.right is the standard.

You can move your ball to its right with this code:

void Update()
{
    GetComponent<Rigidbody2D>().velocity = transform.right * speed;
}

If you run this code the ball will always move into the direction of the red arrow. You can see the arrows by selecting the move tool on the top left and then clicking on your ball inside the editor.

If you want to have your ball to always follow the green arrow you have to use transform.up.

transform.right and transform.up are both used relative to your object. That means by changing the z rotation of your object you can modify the direction it should go in.

You can try out the following code to see your ball move to its right and rotate slowly on its z axis. This will cause the ball to move in a circle since it is still following the red arrow.

void Update()
{

    GetComponent<Rigidbody2D>().velocity = transform.right * speed;

    float speedRotate = 100;
    transform.Rotate(Vector3.forward * speedRotate * Time.deltaTime);
}

When you always want to move an object to the right, no matter the rotation, you use Vector3.right instead of transform.right.

From your other comments I understand that you want your ball to always face into the direction in the middle of the screen. You can just rotate it to the middle of the screen when it spawns by using this code:

void Start()
{
    transform.right = new Vector3(0, 0, 0) - transform.position;
}

This will get the ball to face the 0,0,0 position inside of your world. If 0,0,0 is in the middle of your screen it will face that direction. Otherwise you have to find out which coordinate your middle of your screen has.

Upvotes: 1

Skylar Stickley
Skylar Stickley

Reputation: 27

I'm not sure what you're asking, but you can do ballRigidbody.velocity = transform.foward*speed, to make it go in the current direction it is facing.

If you want a ball you spawn on the left side of the screen to move to the right only, then set velocity like rb.velocity = Vector3.right * speed, and so on with each direction.

Upvotes: 0

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