Rigidbody2D.velocity

Description

Linear velocity of the rigidbody.

The velocity is specified as a vector with components in the X and Y directions (there is no Z direction in 2D physics). The value is not usually set directly but rather by using forces. Disable drag in the Inspector to stop the gradual decay of the velocity.

See Also: AddForce, drag, angularVelocity, Rigidbody.velocity.

//Create a GameObject and attach a Rigidbody2D component to it (Add Component > Physics2D > Rigidbody2D)
//Attach this script to the GameObject

//This script moves a GameObject up or down when you press the up or down arrow keys.
//The velocity is set to the Vector2() value.  Unchanging the Vector2() keeps the
//GameObject moving at a contant rate.

using UnityEngine;

public class ExampleClass : MonoBehaviour
{
    private Rigidbody2D rb;

    private float t = 0.0f;
    private bool moving = false;

    void Awake()
    {
        SpriteRenderer sprRend = gameObject.AddComponent<SpriteRenderer>() as SpriteRenderer;

        rb = gameObject.AddComponent<Rigidbody2D>() as Rigidbody2D;
        rb.bodyType = RigidbodyType2D.Kinematic;
    }

    void Start()
    {
        gameObject.GetComponent<SpriteRenderer>().sprite = Resources.Load<Sprite>("image128x128");
        gameObject.transform.Translate(0.0f, 0.0f, 0.0f);
    }

    void Update()
    {
        //Press the Up arrow key to move the RigidBody upwards
        if (Input.GetKey(KeyCode.UpArrow))
        {
            rb.velocity = new Vector2(0.0f, 2.0f);
            moving = true;
            t = 0.0f;
        }

        //Press the Down arrow key to move the RigidBody downwards
        if (Input.GetKey(KeyCode.DownArrow))
        {
            rb.velocity = new Vector2(0.0f, -1.0f);
            moving = true;
            t = 0.0f;
        }

        if (moving)
        {
            // Record the time spent moving up or down.
            // When this is 1sec then display info
            t = t + Time.deltaTime;
            if (t > 1.0f)
            {
                Debug.Log(gameObject.transform.position.y + " : " + t);
                t = 0.0f;
            }
        }
    }
}