I'm currently working on an exam project, where I'm using TUIO as an input device for my Unity setup. The idea is to use fiducials to create various inputs (in this case the values 1 though 6, to simulate an ordinary six-sided die), that will then be registered within Unity. OnTriggerEnter works fine with my current setup, correctly changing the color of tiles based on the 1-6 input. OnTriggerExit however, which is supposed to change the tile color to white when the tiles are not being triggered, never triggers. The problem seems to be that the TUIO setup creates clones of the in-engine prefabs, which disappear after the corresponding input device is removed. Thus, Unity doesn't register that the trigger "exits" as it should, since the object simply just disappears entirely. I have tried countless solutions, but none have worked so far.
Here is the code I have been using for my triggers.
function Start () {
}
function Update () {
}
function OnTriggerEnter (other: Collider) {
if (other.CompareTag("Player")) {
renderer.material.color = Color.red;
}
}
function OnTriggerExit (other: Collider) {
if (other.CompareTag("Player")) {
renderer.material.color = Color.white;
}
}
Related
Basically on my map I'm trying to use Physics.CheckBox detect when the player is in certain areas to determine where my enemies will spawn at. I am using a layer mask to detect when its colliding with the player and Gizmos to visualize this box in the editor. The issue I'm having is that it will return true even when the player isn't inside the box. I have verified every single other game item does not have the player layer mask causing it to return true when it hits something else. The kicker is Physics.CheckSphere works perfectly except for the fact that my map is square, not circle, so I can't use check sphere because I can't cover all of the areas I need to cover.
Code for both is as follows, note that both of these lines are not in my script at the same time I alternated them out for testing:
atNeighborhood = Physics.CheckSphere(spawnAreas[0].transform.position, neighborhoodRange, playerLayer);
atNeighborhood = Physics.CheckBox(spawnAreas[0].transform.position, neighborhoodRange, Quaternion.identity, playerLayer);
Why would the CheckBox return true when colliding with items not in the layer mask but the CheckSpere works perfectly and only returns true when colliding with the player? Anyone have any idea?
LET ME KNOW IF THERE ARE ANY PROBLEMS OR ERRORS IN COMMENTS. THANKS!
Ok. CheckBox can get kind of confusing sometimes. I would reccomend something else.
You could use Empty Game Objects with colliders on them and put them where ever you want. IsTrigger must be set to true. Imagine these as "zones", where whenever you step in one, something can happen.
All you have to do is set a certain tag to each zone to activate different things.
Note: Player does not need rigidbody, but it would be a whole lot less messy if you did.
Here is a script if your player does have a rigidbody (put this script on your player):
void OnTriggerEnter(Collider obj)
{
if (obj.gameObject.CompareTag("Zone 1"))
{
SpawnZombies();
}
}
Player doesn't have rigidbody:
If your player does not have a rigidbody, you could put a bunch a script on each one called "zone activator".
Important Notes for this version:
Your player must have a collider and a unique tag.
On each zone add a rigidbody.
Make sure detectCollisions is false!
Make sure useGravity is false!
This zone detector should have it's collider be a trigger;
(You do not want this thing to move!)
You can now create a script that goes on each zone:
public string message;
public bool inZone;
void OnTriggerEnter(Collider obj)
{
if (obj.gameObject.CompareTag("player"))
//Or set it to whatever tag the player has
{
inZone = true;
}
}
void OnTriggerExit(Collider obj)
{
if (obj.gameObject.CompareTag("player"))
//Or set it to whatever tag the player has
{
inZone = false;
}
}
You must then reference this in the player's script
public ZoneDetector[] allZones;
void Update()
{
//.....
foreach (ZoneDetector zone in allZones)
{
if (zone.inZone == true)
{
if (zone.message == "zone 1")
{
DoZone1();
}
if (zone.message == "zone 2")
{
DoZone2();
}
}
}
}
I am struggling to find a good tutorial or informations that would allow me to select multiple objects in 3D in a user friendly manner.
So far, the best tutorial I found is this one : https://sharpcoderblog.com/blog/unity-3d-rts-style-unit-selection. The tutorial works by using the transform.position of the selectable objects and checking if it within the user's selection.
What I wish is to have the user be able to select a unit even if it is only partially within the user's selection such as most RTS games do ( both in 2D and 3D ).
One possibility would be to create a temporary mesh using the camera's clipping distances and the user's selection and then check for collisions but I was not able to find any tutorials using this method nor do I know if it is the best approach to the subject.
If I understand correctly you want to
somehow start a selection
collect every object that was "hit" during the collection
somehow end the collection
Couldn't you simply use raycasting? I will assume simple mouse input for now but you could basically port this to whatever input you have.
// Just a little helper class for an event in the Inspector you can add listeners to
[SerializeField]
public class SelectionEvent : UnityEvent<HashSet<GameObject>> { }
public class SelectionController : MonoBehaviour
{
// Adjust via the Inspector and select layers that shall be selectable
[SerializeField] private LayerMask includeLayers;
// Add your custom callbacks here either via code or the Inspector
public SelectionEvent OnSelectionChanged;
// Collects the current selection
private HashSet<GameObject> selection = new HashSet<GameObject>();
// Stores the current Coroutine controlling he selection process
private Coroutine selectionRoutine;
// If possible already reference via the Inspector
[SerializeField] private Camera _mainCamera;
// Otherwise get it once on runtime
private void Awake ()
{
if(!_mainCamera) _mainCamera = Camera.main;
}
// Depending on how exactly you want to start and stop the selection
private void Update()
{
if(Input.GetMouseButtonDown(0))
{
StartSelection();
}
if(Input.GetMouseButtonUp(0))
{
EndSelection();
}
}
public void StartSelection()
{
// if there is already a selection running you don't wanr to start another one
if(selectionRoutine != null) return;
selectionRoutine = StartCoroutine (SelectionRoutine ());
}
public void EndSelection()
{
// If there is no selection running then you can't end one
if(selectionRoutine == null) return;
StopCoroutine (selectionRoutine);
selectionRoutine = null;
// Inform all listeners about the new selection
OnSelectionChanged.Invoke(new HashSet<GameObject>(selection);
}
private IEnumerator SelectionRoutine()
{
// Start with an empty selection
selection.Clear();
// This is ok in a Coroutine as long as you yield somewhere within it
while(true)
{
// Get the ray shooting forward from the camera at the mouse position
// for other inputs simply replace this according to your needs
var ray = _mainCamera.ScreenPointToRay(Input.mousePosition);
// Check if you hit any object
if(Physics.Raycast(ray, out var hit, layerMask = includeLayers ))
{
// If so Add it once to your selection
if(!selection.Contains(hit.gameObject)) selection.Add(hit.gameObject);
}
// IMPORTANT: Tells Unity to "pause" here, render this frame
// and continue from here in the next frame
// (without this your app would freeze in an endless loop!)
yield return null;
}
}
}
Ofcourse you could do it directly in Update in this example but I wanted to provide it in a way where you can easily exchange the input method according to your needs ;)
From UX side you additionally might want to call a second event like OnSelectionPreviewUpdate or something like this every time you add a new object to the selection in order to be able to e.g. visualize the selection outcome.
I might have understood this wrong and it sounds like you rather wanted to get everything inside of a drawn shape.
This is slightly more complex but here would be my idea for that:
Have a dummy selection Rigidbody object that by default is disabled and does nothing
don't even have a renderer on it but a mesh filter and mesh collider
while you "draw" create a mesh based on the input
then use Rigidbody.SweepTestAll in order to check if you hit anything with it
Typed on smartphone but I hope the idea gets clear
I think I would try to create a PolygonCollider2D because it is quite simple comparing to creating a mesh. You can set its path (outline) by giving it 2D points like location of your pointer/mouse. Use the SetPath method for it. You can then use one of its methods to check if another point in space overlaps with that collider shape.
While the PolygonCollider2D interacts with 2D components you can still use its Collider2D.OverlapPoint method to check positions/bounds of your 3D objects after translating it to 2D space.
You can also use its CreateMesh method to create a mesh for drawing your selection area on the screen.
You can read more about the PolygonCollider2D here.
Hope it makes sens and hope it helps.
I have a player object which has (along with other components and objects) a Rigidbody2D, a Collider2D, a PhotonView, and a script called "PhotonLagCompensationView" attached to it. PhotonLagCompensationView syncs the position and velocity of the attached Rigidbody2D, and applies lag compensation like so:
public void OnPhotonSerializeView(PhotonStream stream, PhotonMessageInfo info)
{
if (stream.IsWriting)
{
stream.SendNext(rigidBody2D.position);
stream.SendNext(rigidBody2D.velocity);
}
else
{
networkedPosition = (Vector2)stream.ReceiveNext();
networkedVelocity = (Vector2)stream.ReceiveNext();
float lag = Mathf.Abs((float)(PhotonNetwork.Time - info.SentServerTime));
networkedPosition += networkedVelocity * lag;
}
}
void FixedUpdate()
{
if (!photonView.IsMine)
{
rigidBody2D.velocity = networkedVelocity;
rigidBody2D.position = Vector2.Lerp(
rigidBody2D.position, networkedPosition, Time.fixedDeltaTime * interpolateRate);
}
}
The issue is when I try to call Rigidbody2D.AddForce() on that GameObject, the velocity wont even stutter. What blows my mind about this though is that when I call the EXACT SAME FUNCTION on a different script, it works just fine on all players in the room.
The script that is not working is "KnockBackOnTrigger" which is attached to an object which is instantiated over the network by the player. This object has a Collider2D which is a trigger, and a PhotonView. The OnTriggerEnter2D callback is working just fine. It prints "trigger", and I've even Debug.logged the AddForce() parameters, and a TryGetComponent<>() to make sure the Rigidbody is being recognized and it's applying force properly. The script applies force like this:
void OnTriggerEnter2D(Collider2D collider)
{
if(collider.gameObject.layer == 9 && collider.gameObject != PlayerManager.LocalPlayerInstance)
{
Debug.Log("trigger");
collider.gameObject.GetComponent<Rigidbody2D>().AddForce(
new Vector2(this.transform.localScale.x * knockBackForce, 0),ForceMode2D.Impulse);
}
}
Triggers show up, Rigidbody2D shows up, no moveme
The script that is working is a script attached to the "Lava Blocks" Gameobject which is a tilemap object. The tilemap object for the lava blocks has all the tilemap components attached to it (map, renderer, collider) and they work as intended, as well as the script attached to it. The "LavaBlocks" script works like this:
void OnCollisionEnter2D(Collision2D collision)
{ // everything inside this statement will happen to the player when it touches lava.
if (collision.gameObject.layer == 9)
{
collision.gameObject.GetComponent<Rigidbody2D>().AddForce(
Vector2.up * upwardForce, ForceMode2D.Impulse);
}
}
So whenever a player touches one of the Lava tiles' collider, it bounces upward.
Additionally, I've tried setting the velocity of the Rigidbody2D, which did not work either. This is in fact what I originally wanted to do with the script, but I tried AddForce() to see if that would work.
At one point I even tried to just use the player's CharacterController2D.Move() function to just smack the player's position some units to the left/right, and even this did not do anything.
I made a pretty basic 2D game to learn. I have 2 Scenes, and switching between them worked great. I used empty gameObjects as Start/Exit point of the Scene, so that the game would know to put player on point X after exiting through point X (for example exit outside house if I walk out the door).
Then I added a "Scene0", to use for persistent general scripts like GameManager, Sounds, Music, etc. With just one object called "Controller" that I DontDestroyOnLoad().
After adding this Scene and then just switching Scenes right away to my MainScene, all of a sudden the game starts acting really strange;
the first time I move from my MainScene (Scene1), to my secondary Scene (Scene2), it works fine, but then when I leave Scene2 to go back to Scene1, the player spawns in the middle of nowhere.
And this ONLY happens if I launch the game from my Persistent Scene.
I have no idea what is wrong, I don't add anything that interferes with my scene transitions, all I've added so far is playerHealth, for testing.
Scripts attached to my (persistent) Controller:
DDOL:
public class DDOL : MonoBehaviour {
// Use this for initialization
void Awake () {
DontDestroyOnLoad (gameObject);
}
}
GameManager:
public class GameManager : MonoBehaviour {
public static GameManager manager;
public int playerMaxHealth;
public int playerCurrentHealth;
void Awake(){
if (manager == null) {
manager = this;
} else if (manager != this) {
Destroy (gameObject);
}
}
// Use this for initialization
void Start () {
SceneManager.LoadScene("test_scene");
}
// Update is called once per frame
void Update () {
}
}
Scripts attached to my StartPoint:
PlayerStartPoint:
public class PlayerStartPoint : MonoBehaviour {
private PlayerController thePlayer;
private CameraController theCamera;
public Vector2 startDir;
public string pointName;
// Use this for initialization
void Start () {
thePlayer = FindObjectOfType<PlayerController> ();
if (thePlayer.startPoint == pointName) {
thePlayer.transform.position = transform.position;
thePlayer.lastMove = startDir;
theCamera = FindObjectOfType<CameraController> ();
theCamera.transform.position = new Vector3(transform.position.x, transform.position.y, theCamera.transform.position.z);
}
}
}
And finally ExitPoint:
LoadNewArea:
public class LoadNewArea : MonoBehaviour {
public string levelToLoad;
public string exitPoint;
private PlayerController thePlayer;
// Use this for initialization
void Start () {
thePlayer = FindObjectOfType<PlayerController> ();
}
void OnTriggerEnter2D(Collider2D other){
if (other.gameObject.name == "Player")
{
SceneManager.LoadScene(levelToLoad);
thePlayer.startPoint = exitPoint;
}
}
}
EDIT:
After moving all my DDOL gameObject to the Pre-Scene, it worked. So, I can assume the fault is inside Player or Cameras Start() functions since when they start in Scene1 they get called every time I enter the Scene (only DDOL).
I tried adjusting their Start()functions like follows:
Original camera:
void Start () {
Debug.Log("Starting camera");
if (!cameraExists) {
cameraExists = true;
DontDestroyOnLoad (gameObject);}
else{
Destroy (gameObject);
}
}
Changed Camera:
void Start () {
DontDestroyOnLoad (gameObject);
}
The exact same changes was made in Player.
Obviously this doesnt work because it creates a new Camera/Player every time I enter Scene1 (btw why does it not try to create them when I enter Scene2?, is it because they start in Scene1?). HOWEVER, the new player/camera do start at the correct position, and if I zoom out I can see the old player/camera at that same wrong position as before. So something weird happens when their Start() is called a second time it seems.
You've now mentioned that you had code something like this,
void Start () {
Debug.Log("Starting camera");
if (!cameraExists) {
cameraExists = true;
DontDestroyOnLoad (gameObject);}
else{
Destroy (gameObject);
}
}
Note that this is unfortunately just "utterly incorrect", heh :)
The issues you mention in the question (preload scenes etc) are just totally unrelated to the problem here.
In Unity if you have a character C that persists between scenes a, b, c as you load those scenes, you must kick-off C in it's own (perhaps otherwise empty) scene, you can not use "a" as a matter of convenience to kick off C.
The pattern is, in each of a, b, c just have a line of code like p = FindObjectOfType<Player>(); which runs when the scene loads, and position C as you wish.
Now, regarding your specific puzzle about the unusual behavior you are seeing.
I understand that you want to know why you are observing what you do.
It is a combination of confusion over the following issues: 1 - difference between Awake and Start, 2 - confusion over script execution order {but see below1} 3 - confusion about Destroy versus DestroyImmediate 4 - Not using Debug.Log enough, and not using gameObject.name in there (it's a common in Unity to be wildly confused about which object is talking in Debug.Log) 5 - where you mention you see the other object "off to the side", it's common to drastically confuse which one is which in such situations 6 - confusion between the computer programming concept of "instantiation" (ie, of a class or object) and "instantiating" (confusingly, it's the same word - utterly unrelated) game objects in nity.
If you fiddle around with all those issues, you'll discover an explanation for the behavior you're seeing!
But it doesn't amount to much; in Unity in the "C .. a b c" example you have to create C separately beforehand.
1 {aside, never fiddle with the script execution ordering system in Unity in an effort to solve problems; it's only there for R&D purposes; however it could in fact help you investigate the behavior at hand in this problem, if you are particularly keen to fully understand why you're seeing what you're apparently seeing}
Use the debugger. Have breakpoints at the relevant spots, like PlayerStartPoint.Start() and LoadNewArea.OnTriggerEnter2D() and check that they are executed
At the right time
The right number of times
With the expected values
This should make you see where things get out of hand.
If you use Visual Studio, install https://marketplace.visualstudio.com/items?itemName=SebastienLebreton.VisualStudio2015ToolsforUnity to be able to debug Unity from within Visual Studio.
If you are not using Visual Studio, you probably should.
Is player persistent between scenes (does he have DontDestroyOnLoad)? If no then this might be the reason - you can either try loading the scenes by using the additive mode or by instantiating the player on scene load in correct position.
I'm concerned over the difference between OnPointerDown versus OnBeginDrag in single-finger movement code.
(In the latest Unity paradigm of using a physics raycaster: so, finally, Unity will properly ignore touch on the UI layer.
So from 2015 onwards what you must do is this:
Forget about the crap traditional Input or Touches system which are pointless crap and don't work
Add an empty game object with a usually BoxCollider2D, likely bigger than the screen. Make the layer called say "Draw". Physics settings, "Draw" interacts with nothing
Simply add to the camera, a 2D or 3D physics raycaster. Event mask the "Draw" layer.
Do a script like below and put it on.
(Tip - don't forget to simply add an EventSystem to the scene. Bizarrely, Unity does not do this automatically for you in some situations but Unity does do it automatically for you in other situations, so it's annoying if you forget!)
But here's the problem.
There has got to be some subtle difference between using OnPointerDown versus OnBeginDrag (and the matching end calls). (You can just swap the action in the following code sample.)
Naturally Unity offers no guidance on this; the following code beautifully rejects stray grabs and also flawlessly ignores your UI layer (thanks Unity! at last!) but I am mystified about the difference between the two approaches (begin drag V. begin touch) and I cannot in anyway find the logical difference between the two in unit testing.
What's the answer?
/*
general movement of something by a finger.
*/
using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;
public class FingerMove:MonoBehaviour,
IPointerDownHandler,
IBeginDragHandler,
IDragHandler,
IPointerUpHandler,
IEndDragHandler
{
public Transform moveThis;
private Camera theCam;
private FourLimits thingLimits;
private Vector3 prevPointWorldSpace;
private Vector3 thisPointWorldSpace;
private Vector3 realWorldTravel;
public void Awake()
{
theCam = Camera.main or whatever;
}
public void OnMarkersReady() // (would be EVENT DRIVEN for liveness)
{
thingLimits = Grid.liveMarkers. your motion limits
}
private int drawFinger;
private bool drawFingerAlreadyDown;
public void OnPointerDown (PointerEventData data)
{
Debug.Log(" P DOWN " +data.pointerId.ToString() );
}
public void OnBeginDrag (PointerEventData data)
{
Debug.Log(" BEGIN DRAG " +data.pointerId.ToString() );
if (drawFingerAlreadyDown == true)
{
Debug.Log(" IGNORE THAT DOWN! " +data.pointerId.ToString() );
return;
}
drawFinger = data.pointerId;
drawFingerAlreadyDown=true;
prevPointWorldSpace = theCam.ScreenToWorldPoint( data.position );
}
public void OnDrag (PointerEventData data)
{
Debug.Log(" ON DRAG " +data.pointerId.ToString() );
if (drawFingerAlreadyDown == false)
{
Debug.Log(" IGNORE THAT PHANTOM! " +data.pointerId.ToString() );
}
if ( drawFinger != data.pointerId )
{
Debug.Log(" IGNORE THAT DRAG! " +data.pointerId.ToString() );
return;
}
thisPointWorldSpace = theCam.ScreenToWorldPoint( data.position );
realWorldTravel = thisPointWorldSpace - prevPointWorldSpace;
_processRealWorldtravel();
prevPointWorldSpace = thisPointWorldSpace;
}
public void OnEndDrag (PointerEventData data)
{
Debug.Log(" END DRAG " +data.pointerId.ToString() );
if ( drawFinger != data.pointerId )
{
Debug.Log(" IGNORE THAT UP! " +data.pointerId.ToString() );
return;
}
drawFingerAlreadyDown = false;
}
public void OnPointerUp (PointerEventData data)
{
Debug.Log(" P UP " +data.pointerId.ToString() );
}
private void _processRealWorldtravel()
{
if ( Grid. your pause concept .Paused ) return;
// potential new position...
Vector3 pot = moveThis.position + realWorldTravel;
// almost always, squeeze to a limits box...
// (whether the live screen size, or some other box)
if (pot.x < thingLimits.left) pot.x = thingLimits.left;
if (pot.y > thingLimits.top) pot.y = thingLimits.top;
if (pot.x > thingLimits.right) pot.x = thingLimits.right;
if (pot.y < thingLimits.bottom) pot.y = thingLimits.bottom;
// kinematic ... moveThis.position = pot;
// or
// if pushing around physics bodies ... rigidbody.MovePosition(pot);
}
}
And here's a handy thing. Save typing with the same thing for 3D scenes, using the little-known but exquisite
pointerCurrentRaycast
here's how... notice the excellent
data.pointerCurrentRaycast.worldPosition
call courtesy Unity.
public class FingerDrag .. for 3D scenes:MonoBehaviour,
IPointerDownHandler,
IDragHandler,
IPointerUpHandler
{
public Transform moveMe;
private Vector3 prevPointWorldSpace;
private Vector3 thisPointWorldSpace;
private Vector3 realWorldTravel;
private int drawFinger;
private bool drawFingerAlreadyDown;
public void OnPointerDown (PointerEventData data)
{
if (drawFingerAlreadyDown == true)
return;
drawFinger = data.pointerId;
drawFingerAlreadyDown=true;
prevPointWorldSpace = data.pointerCurrentRaycast.worldPosition;
// in this example we'll put it under finger control...
moveMe.GetComponent<Rigidbody>().isKinematic = false;
}
public void OnDrag (PointerEventData data)
{
if (drawFingerAlreadyDown == false)
return;
if ( drawFinger != data.pointerId )
return;
thisPointWorldSpace = data.pointerCurrentRaycast.worldPosition;
realWorldTravel = thisPointWorldSpace - prevPointWorldSpace;
_processRealWorldtravel();
prevPointWorldSpace = thisPointWorldSpace;
}
public void OnPointerUp (PointerEventData data)
{
if ( drawFinger != data.pointerId )
return;
drawFingerAlreadyDown = false;
moveMe.GetComponent<Rigidbody>().isKinematic = false;
moveMe = null;
}
private void _processRealWorldtravel()
{
Vector3 pot = moveMe.position;
pot.x += realWorldTravel.x;
pot.y += realWorldTravel.y;
moveMe.position = pot;
}
}
I want to start by saying that Input and Touches are not crappy.They are still usefull and were the best way to check for touch on mobile devices before OnPointerDown and OnBeginDrag came along. OnMouseDown() you can call crappy because it was not optimized for mobile. For a beginner who just started to learn Unity, Input and Touches are their options.
As for your question, OnPointerDown and OnBeginDrag are NOT the-same. Although they almost do the-same thing but they were implemented to perform in different ways. Below I will describe most of these:
OnPointerDown:
Called when there is press/touch on the screen (when there is a click or finger is pressed down on touch screen)
OnPointerUp:
Called when press/touch is released (when click is released or finger is removed from the touch screen)
OnBeginDrag:
Called once before a drag is started(when the finger/mouse is moved for the first time while down)
OnDrag :
Repeatedly called when user is dragging on the screen (when the finger/mouse is moving on the touch screen)
OnEndDrag:
Called when drag stops (when the finger/mouse is no longer moving on the touch screen).
OnPointerDown versus OnBeginDrag and OnEndDrag
OnPointerUp will NOT be called if OnPointerDown has not been called. OnEndDrag will NOT be called if OnBeginDrag has not been called. Its like the curly braces in C++,C#, you open it '{' and you close it '}'.
THE DIFFERENCE:
OnPointerDown will be called once and immediately when finger/mouse is on the touch screen. Nothing else will happen until there is a mouse movement or the finger moves on the screen then OnBeginDrag will be called once followed by OnDrag.
These are made for doing advanced usage such such as custom UI with controls that is not included in Unity.
WHEN TO USE EACH ONE:
1. When you have to implement a simple click button, for example, Up,Down, Shoot Button on the screen, you only need OnPointerDown to detect the touch. This should work for Sprite Images.
2. When you have to implement a custom toggle switch and you want it to be realistic so that the player can drag to left/right or up/down to toggle it then you need OnPointerDown , OnBeginDrag , OnDrag , OnEndDrag , OnPointerUp. You need to write your code in this order to have a smooth Sprite/Texture transition on the screen. Some toggle switches are made to be to clicked and it will toggle. Some people prefer to make it look realistic by making it so that you have to drag it in order to toggle it.
3. Also when you want to implement a Generic re-usable pop-up window that is draggable, you also need to use those 5 functions (OnPointerDown , OnBeginDrag , OnDrag , OnEndDrag , OnPointerUp).
First detect when there is a click(OnPointerDown), check to make sure that the Sprite clicked is the right one you want to move. Wait for player to move(OnBeginDrag) their finger/mouse. Once they start dragging, maybe you can call a coroutine function with while loop that will start moving the Sprite and inside that coroutine, you can smooth the movement of the Sprite with Time.deltaTime or any other preferred method.
Since OnBeginDrag is called once, it is a good place to start the coroutine.
As the player continue to drag the Sprite, OnDrag will be called repeatedly. Use the OnDrag function to get the current location of the finder and update that to a Vector3 that the coroutine that is already running will use to update the position of the Sprite. When the player stops moving their finger/mouse on the screen, OnEndDrag is called and you can boolean variable and tell the coroutine to stop updating the position of the Sprite. Then, when the player releases their finger(OnPointerUp) you can then stop the coroutine with the StopCoroutine function.
Because of OnBeginDrag we we are able to start coroutine once drag started while waiting for drag to end. It wouldn't make sense to start that coroutine in OnPointerDown because that means that each time player touches the screen, a coroutine would be started.
Without OnBeginDrag, we have to use boolean variable to make the coroutine start only once in the OnDrag function which is called every time or else there would be coroutine running everywhere and unexpected movement of the Sprite will occur.
4. When you want to determine how long player moved their finger. Example of this is that famous game called Fruit Ninja. Lets just say you want to determine far the player swiped on the screen.
First, wait until OnPointerDown is called, wait again until OnBeginDrag is called, then you can get the current position of the finger inside OnBeginDrag function because OnBeginDrag is called before the finger starts moving. After the finger is released, OnEndDrag is called. Then you can get the current position of finger again. You can use these two positions to check how far the finger moved by subtracting them.
If you instead decide to use OnPointerDown as the place to get the first position of the finger, you will get a wrong result because if the player swipes right, then waits and swipes left then waits again and swipe up without releasing their finger after each swipe, the only good result you have is the first swipe(right swipe). The left and the up swipe will have invalid values because that first value you got when OnPointerDown was called is the value you are still using. This is because the player never removed their finger from the screen so therefore, OnPointerDown is never called again and the first old old value is still there.
But when you use OnBeginDrag instead of OnPointerDown, this problem will be gone because when the finger stops moving, OnEndDrag is called and when it starts moving again OnBeginDrag is called once again causing the first position to be overwritten with the new one.
The difference is that OnBeginDrag doesn't get called until the touch/mouse has moved a certain minimum distance, the drag threshold. You can set the drag threshold on the Event System component.
This is necessary for when you have a hierarchy of objects with different ways of handling input, especially scrollviews. Imagine you have a scrollview with a vertical stack of cells, each with a button in it. When the touch first starts on one of the buttons, we don't know whether the user is tapping a button or dragging the scrollview. It isn't until the touch gets dragged for the drag threshold that we know it is a drag and not a tap.