Bug First position of touch contact is 0,0

I have these actions, mainly the primary touch position and contact


Code:

Code (CSharp):

1.  
2.     private void Start() {
3.         // Subscribe to input action touch events
4.         touchControls.Touch.TouchPress.performed += ctx => StartTouch(ctx);
5.         touchControls.Touch.TouchPress.canceled += ctx => EndTouch(ctx);
6.     }
7.  
8.     private void StartTouch(InputAction.CallbackContext context) {
9.         Debug.Log("Touch started " + touchControls.Touch.TouchPosition.ReadValue<Vector2>());
10.         if (OnStartTouch != null) OnStartTouch(touchControls.Touch.TouchPosition.ReadValue<Vector2>(), (float)context.startTime);
11.     }
12.  

The first value printed is always 0, 0 for the screen position. This has happened to someone else I know as well. The other values are fine after the first one. The input debugger also shows the correct position. Seems like a bug to me. Any way around this? Thanks!

 

Ditto!

 

Im using the same code as samyam_ and in my case y have one and one. First is (0,0), second is OK, third is (0,0), etc.

 

I'm using the "touch contact?" as well, which works fine on most phones, but apparently returns 0,0 on some...

 

This is happening to me as well, has anybody discovered a workaround or resolution to this?

 

+1

 

Funnily enough I was following a tutorial by the OP and im still having this issue. @samyam_ did you ever find a fix for this?

 

No I didn't unfortunately for this case, but you can use the EnhancedTouch API as a workaround to get the position

 

Having the same issue, not just on some phones, but all phones I tried and also with simulated touch on Unity Editor. The first touch is always (0,0)

I don't know what to do...

 

Have a found a workaround though:
I tried using a delay of 0.1f seconds using Coroutine to read the first value after 0.1 seconds. I did this Only for first touch value after loading a scene, using a bool variable, since the problem exists only in the first touch value calculated in the first frame after touch.

Then I modified that 0.1f seconds to Time.deltaTime to wait only one iteration of Update. I realized that giving a fixed time may or may not work on different devices so am using Time.deltaTime.

This still could cause issues I reckon, but should work most of the times

 

So... I ran into this myself...using your guide Samyam, and by the way, thank you it's awesome!
Anyway, I found out that this is specifically related to PRIMARY TOUCH. Seriously. I swapped my TouchPress Binding to Touch#0/Touch Contact?
And it fixed the issue for me.

I'm using 2021.2.7f1

 

Confirmed! After changing from Primary Touch to Touch #0 the first touch position started to work beautifully. Thank you! Seems like something Unity should be fixing.

 

UNconfirmed by me

I changed to Touch#0/Touch Contact? [Touchscreen]
and still get (0,0) as first point.

I'll try @samyam_ suggestion above & see if that fixes it.

(On a related note, & I know IU should make a separate post...) I have my own action to alter the coordinates of my touch screen and it only shows up in the drop down after some convoluted sequence of events I havent managed to nail down!)

 

I wonder if this bug fix in 2021.3.5 fixes this: https://issuetracker.unity3d.com/issues/mouse-coordinates-reported-as-00-until-the-first-move

 

Using 2022.1.18.f1 and same issue. Rawposition returns 0,0 i am using old input system

 

Checking "Initial State Check" on the passthrough for Touch #0/Position fixed for me. Not sure if it is good practice, but I suspect it has something to do with initialization done on the first touch. So I figured checking this box would force it to initialize.



Hope this helps.

 

Original post is a bit old, but in this thread are a lot of error-prone answers.

You don't need the enhanced touch API or stuff like that. You can do it by correctly setting up an action:

Create an action and then click "Add Binding with one modifier".
Set it up like shown here:


Modifier is the thing that will trigger the action.
Binding is the value you'll get in the code, so you can just do a

ReadValue<Vector2>

to get the touch position.

 

Thanks, works perfectly with any touch!

 

By setting up my actions using this method I was able to reliably detect swipes with no errant input (like 0, 0 on the first swipe detection....)

In case someone else ends up here via Google like I did:

Set up your action like ManuelRauber says
In the started event, save the starting position/time
In the performed event, save the current position/time
In the canceled event, use the last current position/time and that will be your ending position and time
???
Profit!

The resulting positions are screen co-ordinates, so if you want, use Camera.main.ScreenToWorldPoint(position) for interacting with game objects.

 

Setting up like this makes position to be 0,0 when called from the canceled event.

As JonTheCoder said, you have to register the "current" position every "performed" event.

REALLY weird.

[Edit]

WAIT "performed" is not triggering every frame, it does it in the beginning.
This logic is not working.

You have to ask for the last positions every frame on your own.
I added a "OnTouch" on my InputManager wrapper that gets called every frame between "started" and "canceled".

 

Touchscreen and Mouse are control schemes and both are driven by the mouse only anyway.

Tested further, seems like Touchscreen Simulation causes the first touch to be (0,0). Using just Touchscreen + GameView has no first touch (0,0)

 

Thanks a lot. It is working perfectly now.

 

I don't think you've set it up correctly... I've just implemented this using the suggestions including tracking the last position with .performed and it appears to be working as expected.