Unity - How to instantiate new object with initial properties (like velocity)? - unity3d

I'm trying to implement a tower defense game in Unity, and I can't figure out how can I assign a velocity or a force to a new instantiated object (in the creator object's script)
I have a tower which is supposed to shoot a bullet towards the enemy which triggered its collider. This is the script of the towers:
function OnTriggerEnter(other:Collider){
if(other.name=="Enemy")
{
ShootBulletTo(other.transform);
}
}
function ShootBulletTo(target:Transform)
{//public var Bullet:Transform
var BulletClone = Instantiate(Bullet,transform.position, Quaternion.identity); // ok
BulletClone.AddForce(target.position); //does not compile since Transform.AddForce() does not exist.
}
I guess the problem is I have to use a Transform variable for instantiate but I need a GameObject variable for velocity, force etc. So how can I instantiate the bullet with initial velocity?
Thanks for help.

You have to acces the rigidbody component of your bullet clone to change the force, not the transform.
Here's how your code should look:
function OnTriggerEnter(other:Collider)
{
if(other.name=="Enemy")
{
ShootBulletTo(other.transform);
}
}
function ShootBulletTo(target:Transform)
{
var Bullet : Rigidbody;
BulletClone = Instantiate(Bullet, transform.position, Quaternion.identity);
BulletClone.AddForce(target.position);
}
There's also a good example in the unity script reference
http://docs.unity3d.com/Documentation/ScriptReference/Object.Instantiate.html
[EDIT] I'm pretty sure, that you don't want to add the enemies position as a force, instead you should add a direction that goes towards the enemies position.
You subtract two positions to gain a direction vector between them, so the ShootBulletTo function should look like this:
function ShootBulletTo(target:Transform)
{
// Calculate shoot direction
var direction : Vector3;
direction = (target.position - transform.position).normalized;
// Instantiate the bullet
var Bullet : Rigidbody;
BulletClone = Instantiate(Bullet, transform.position, Quaternion.identity);
// Add force to our bullet
BulletClone.AddForce(direction);
}

Related

How to create a projectile Script in Unity

so recently my friends and I are trying to make a game for fun. Currently, I hit a wall and not sure how to do this. I am trying to create a simple base script where I have the character move and attack with right click. If it hits the ground, it will move there and and if in range of a target, it will send a projectile. So the game is creating the projectile but its not actually moving. Can anyone tell me what I should probably do. At first, I thought to just make it all one script but now I am thinking it be best to make another script for the projectile.
void Update()
{
if (Input.GetMouseButtonDown(1))
{
RaycastHit hit;
if(Physics.Raycast (Camera.main.ScreenPointToRay(Input.mousePosition), out hit) && hit.transform.tag == "Minion")
{
if(Vector3.Distance(this.transform.position, hit.point) <= atkRange)
{
GameObject proj = Instantiate(bullet) as GameObject;
proj.transform.position = Vector3.MoveTowards(this.transform.position, target, atkSpd);
}
}
else if (Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), out hit, speed))
{
agent.destination = hit.point;
}
}
}
So this is what I originally had. I am pretty sure I did something wrong here. Also I am not sure if I should have another script for the projectile itself or if it is not necessary. Thank you for any help or tips on what to do.
For starters, I'd advize using a Rigidbody component and letting physics handle movement but if you'd like to use Vector3.MoveTowards, it'll be a bit of work:
Vector3.MoveTowards is something that needs to be called every frame. I'm guessing bullet is your prefab so you'll want to make a new script for the movement and place it on that prefab:
public class MoveToTarget : MonoBehaviour
{
private float _speed;
private Vector3 _target;
public void StartMovingTowards(Vector3 target, float speed)
{
_target = target;
_speed = speed;
}
public void FixedUpdate()
{
// Speed will be 0 before StartMovingTowards is called so this will do nothing
transform.position = Vector3.MoveTowards(transform.postion, _target, _speed);
}
}
After you've attached this to your prefab, make sure you grab a reference and get it started when you instantiate a copy of your prefab:
GameObject proj = Instantiate(bullet) as GameObject;
var movement = proj.GetComponent<MoveToTarget>();
movement.StartMovingTowards(target, atkSpd);
If you instead go the physics route, add a Rigidbody component to your bullet prefab, and get a reference to that instead of making the MoveToTarget script:
GameObject proj = Instantiate(bullet) as GameObject;
var body = proj.GetComponent<Rigidbody>();
Then you can just apply a force and let physics take over:
body.AddForce(target - transform.position, ForceMode.Impulse);
Don't set the position like you currently are
proj.transform.position = Vector3.MoveTowards(this.transform.position, target, atkSpd);
Instead, add either a characterController or a rigidbody and use rb.addVelocity.

GameObject Follow cursor yet also follows enemies?

I'm making a simple character that follows the player's cursor. What I also want is for when the game object "enemy" appears the character then goes to that location to alert the player. Once the enemy is gone the character continues to follow the cursor like normal. Is there a reason why my script won't work. How else can I paraphrase it?
public class FollowCursor : MonoBehaviour
{
void Update ()
{
//transform.position = Camera.main.ScreenToWorldPoint( new Vector3(Input.mousePosition.x,Input.mousePosition.y,8.75f));
if (gameObject.FindWithTag == "Enemy")
{
GameObject.FindWithTag("Enemy").transform.position
}
if (gameObject.FindWithTag != "Enemy")
{
transform.position = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x,Input.mousePosition.y,8.75f));
}
}
}
You are not using FindWithTag correctly, as it is a method that takes a string as parameter you need to use it like this:
GameObject.FindwithTag("Something") as stated in the Unity scripting API
Now to apply this to your code you would need to do the following to set your players position based on wether or not an enemy is found (assuming this script is on your actual player object):
if(GameObject.FindWithTag("Enemy"))
{
//If an enemy is found with the tag "Enemy", set the position of the object this script is attatched to to be the same as that of the found GameObject.
transform.position = GameObject.FindWithTag("Enemy").transform.position;
}
else
{
//when no enemy with the tag "Enemy" is found, set this GameObject its position to the the same as that of the cursor
transform.position = Camera.main.ScreenToWorldPoint( new Vector3(Input.mousePosition.x,Input.mousePosition.y,8.75f));
}
However this code will just snap your player instantly to the position of the found Enemy. If this is not the desired behaviour you could use a function like Vector3.MoveTowards instead to make the player move to it gradually.
This code also has room for optimisation as searching for a GameObject every update frame is not the ideal solution. But for now it should work.
I'm going to code coding all the function for you, I'm not pretty sure about the beavihour of your code, I understand a gameobject will be attached to the mouse position, so not really following....
Vector3 targetPosition;
public float step = 0.01f;
void Update()
{
//if there is any enemy "near"/close
//targetPosition = enemy.position;
//else
//targetPosition = MouseInput;
transform.position = Vector3.MoveTowards(transform.position, targetPosition , step);
}
For the f you can use a SphereCast and from the enemies returned get the closest one.

Collision not detected by OnTriggerEnter

So I'm trying to make a game about soccer. In this program, I'd created 2 objects called (in Hierarchy): Ball and goal_line_1. In this code, I'm trying to check if the ball collides with the goal line or not, and if it does collide, I will return (Lerp) the ball to the point in the middle (0,0.3,0). But somehow when I drag the ball to the position that the ball collides with the goal line and then press play, the ball just stay there and don't return to the middle point.
public var smooth : float;
private var newPosition : Vector3;
function Awake ()
{
newPosition = transform.position;
}
function OnTriggerEnter (ball : Collider)
{
var positionA : Vector3 = new Vector3(0, 0.3, 0);
newPosition = positionA;
ball.transform.position = Vector3.Lerp(ball.transform.position, newPosition, smooth * Time.deltaTime);
}
That is because you used OnTriggerEnter() function. This function is called when a collider enters a collision with another collider. What you do by dragging the ball into the line and then pressing play is actually skipping the 'Trigger Enter' event. There are three main events when it comes to collisions: TriggerEnter, TriggerStay and TriggerExit.
Although I'm not sure, if you change your function to OnTriggerStay(), you might get your function work. However for a safer testing method, I suggest you add a script to the ball so you can manually move it with your keyboard and see if the OnTriggerEnter() function works because by doing that, you will be simulating a more realistic situation (ball being kicked/moving towards the line rather than "suddenly existing" on the line).
If you are using 2D, you need to change your OnTriggerEnter function to OnTriggerEnter2D.

Set transform from another GameObject's script

I'm trying to make a script to set an object when is being instantiated. The problem is, I don't clearly know how to do it. I have this function..
function spawnPlayer()
{
var CameraScript = GameObject.Find(PlayerPrefab.name).GetComponent("Camera Control");
Network.Instantiate(PlayerPrefab, spawnObject.position, Quaternion.identity, 0);
}
Where PlayerPrefab is going to be the Prefab that's going to be instantiated. When this happens, I need to set the instantiated gameObject on another GameObject which is camera and has a script called "Camera Control" and inside there's a transform Target which I'm trying to set. How to do this?
The code you posted can't be right. You are using the PlayerPrefab's name to to find the Camera Control script attached to the camera? By that logic then the moment you instantiate PlayerPrefab, on the second line, you will have a second camera.
I think what you want to do is this: Instantiate the player prefab and make the camera point to the player.
So I am assuming the CameraControl script is created. You need the following before we start to code.
Attach CameraControl script to the camera in the scene.
Make sure the Player script is attached to the Player Prefab.
Have a third script that will instantiate the PlayerPrefab. I will call it Instantiator. Attach it to an empty GameObject in the scene, think of it as the world GameObject. We will call it World.
Make sure the Instantiator script is attached to the World GameObject and that it is pointing to the PlayerPrefab.
Code: Instantiator
The Instantiator script will spawn and create things we will use in the scene.
#pragma strict
var PlayerPrefab : GameObject;
function Start ()
{
// You can add position and rotation to the function call if you like.
var p = Instantiate(PlayerPrefab) as GameObject;
// Find the camera script and point to Player's transform.
Camera.main.GetComponent("CameraControl").SendMessage("setTarget", p.transform);
}
Notice I used the fact that the MainCamera in the scene is marked by Unity for you so it is easy to find.
Code: CameraControl
The CameraControl will have the logic to follow the Player as you see fit. Notice that target will point to what the camera will focus on. Of course following the Player around you will have to write.
var target : Transform;
function setTarget(t : Transform)
{
target = t;
}
I just taught myself a bit of JavaScript. I had never used it before.
I found my solution.
What I was meaning on my question was to set my camera's script the transform of the instantiated object.
I did not have to make many empty objects with scripts value of each object; it took me hours to find it because I did not know how unity handles the scripts objects calls.
This is how I made it:
var PlayerPrefab : GameObject;
var spawnObject : Transform;
private var MainCamera : GameObject;
function spawnPlayer()
{
var player = Instantiate(PlayerPrefab, spawnObject.position, Quaternion.identity);
MainCamera = GameObject.Find("MainCamera");
player.name = "Ball";
if(MainCamera)
{
MainCamera.GetComponent.<CameraControl>().target = player.transform;
Debug.Log("Succeed.");
}
}
Like this, my camera will have the transform properties of the new instantiated object automatically.

Shooting a ball from the middle of the camera

I;m trying to make the first person character to shoot a ball from the middle of the camera,
but it's just not working.
Here is the first person character's script:
public Rigidbody ball;
void Update () {
if (Input.GetButtonDown ("Fire1")) {
Instantiate(ball,transform.position+new Vector3(0,1,0),transform.rotation);
}
}
and here is the ball's script :
public float speed=20;
Vector3 direction;
void Start () {
direction = Camera.main.transform.forward;
}
void Update () {
transform.Translate(direction *Time.deltaTime*speed);
Destroy(gameObject,3);
}
The ball is prefab.The problem is that the ball is not coming from the center of the camera.
I dont understand why its not working.
Anyone can help me?
Thank you!
The reason why your script does not work is the wrong position in Instantiate function, because you shouldn't assume that that player is facing into positive Y axis direction.
Code of instantiation should look like this:
Instantiate(ball,transform.position + transform.forward*(distance_from_camera),transform.rotation);
We set position to players transform.position increased by "forward" vector (it indicates in which direction object is facing), multiplying this value by distance in which instantiated object will appear.
Edit: 1. In ball script the direction should be just transform.forward.
2. Instantiated ball should have forward direction equal to camera's forward. To achieve this you have to set the ball to be child of camera, the change localRotation to (0, 0, 0). After it "unchild" the ball, so it won't have a parent.
You were so close! you just needed to instantiate it at the cameras position!
void Update () {
if (Input.GetButtonDown ("Fire1")) {
Instantiate(ball,Camera.main.transform.position,transform.rotation);
}
}