How can I make a game object move in parabolic motion as if it were under gravity?

Questions & Answers
1

I am modifying a shooting game where instead of the bullet traveling straight up, I want it to act under gravity and move in a parabolic motion. Right now, I have the bullet moving in a straight line with a positive slope. Is there any way I can change my code for the bullet to make it behave this way? My game is in 2D and also uses the X-axis and Y-axis. Here is the bulletScipt:

var bulletSpeed : int;

var bulletAngle: float;

var explosion : Transform;

useGravity = true;

function FixedUpdate () {
amtToMove = bulletSpeed * Time.deltaTime;

transform.Translate(Vector3.right + Vector3.up * amtToMove);

if(transform.position.y >=6.7){
Destroy(gameObject);
}

if(transform.position.y <= -5){
Destroy(gameObject);
}
}

function OnTriggerEnter(otherObject: Collider){

if(otherObject.gameObject.tag == “enemy”){

playerScript.playerScore += 50;

otherObject.gameObject.transform.position.y = 7;

otherObject.gameObject.transform.position.x = Random.Range(-6,6);

var tempExplosion: Transform;

tempExplosion = Instantiate(explosion, transform.position, transform.rotation);

Destroy(gameObject);

}
}

function OnGUI()
{
GUI.Label(Rect(10,70,200,50),"Bullet Velocity: "+ bulletSpeed);

GUI.Label(Rect(10,90,200,50),"Bullet Angle: "+ bulletAngle);
}

2

Either give the bullet GameObject a Rigidbody with gravity enabled or script your own gravity;

var startPosition : Vector3;
var startTime : float;
function Start () { startPosition = transform.position; startTime = Time.time; }
function Update () { transform.position.y = startPosition - 4.905 * (Time.time-startTime)*(Time.time-startTime) }
3

I believe the iTween library has function for handling that type of animation directly, without having to delve into the math yourself. Might come in handy.

http://itween.pixelplacement.com/index.php