Input.GetTouch (0).position vs. Screen space coordinates

Target Platforms Mobile
1

this is a heavily summarized version of a question i posted in answears but has still not been approved by moderators after 9 hours.
Here are the questions in bullets:

  • To position things in phone i must use 0-1 coordinate system with (0,0) originating bottom-left?

  • Unity screen space uses pixel coordinate system with (0,0) originating top-left?

  • To potentially position something correctly on my phone i would have to, first, convert the values so both coordinate system’s (0,0) are bottom-left, second, i would have to convert the number of pixels in the pixel coordinate system to 0-1 to match the phone positioning system of phone?

  • When script is running in mobile environment and i return the position value of a empty gameobject, does this value already come in 0-1 coordinate system or is it in pixels or in world space?

any answers to any of my questions above would be hugely appreciated :slight_smile:

2

Hej,
Solution is simple - to get the same coordinates as screen you must only deduct scree.height

Vector2 tapPoint;

// Update and Input function
tapPoint = Input.GetTouch(0).position;
tapPoint.y = Screen.height - tapPoint.y;
1 Like
3

@rchmiel thank you sir, you were the absolutely only one who gave enough of a care to even give a small answer to a simple question, surly i can’t rely on the answers section because my question is still pending moderator approval after 2 days now.

Well anyways, i was surprised that Input.GetTouch(0).position gives a pixel value, i have read on multiple posts that to position something on mobile device you have to use 0-1 coordinate system, however after reading the documentation on Input.GetTouch(0).position i see that it actually returns pixels. (so i wonder what that 0-1 coordinate system was for).

I would figure out these things myself but no matter what i try unity will not recognize my phone when it is plugged in (even though dev mode on, usb debugging on, etc.) thus to test something i have to manually drag it into the files and install manually from within the phone, which take considerable amount of time overall.

*so this is what i understood to get the results that i want (confirmation would be appreciated):

  • i use Camera.WorldToScreenPoint to get position values in pixels
  • i invert the .y component of Input.GetTouch(0).position
  • i now have matching coordinate system?

the reason i’m asking is because i’m trying to make a button with position conditional statements but haven’t been able to get it to work.
(to set a position of a gameobject in mobile, do you use pixel coordinate system or some other system?)

4

well i tried integrating this solution into my mobile app but i had to make a change to it.

void Start () {
        camera = GetComponent<Camera>();
        LBpos = camera.WorldToScreenPoint (LB.position);
        RBpos = camera.WorldToScreenPoint (RB.position);
        TBpos = camera.WorldToScreenPoint (TB.position);
        BBpos = camera.WorldToScreenPoint (BB.position);
    }

    void Update () {
        if (Input.touchCount > 0) {
            Vector2 touch = Input.GetTouch(0).position;
            //touch.y = Screen.height - touch.y;
            if (Busy == false && touch.x >= LBpos.x && touch.x <= RBpos.x && touch.y <= TBpos.y && touch.y >= BBpos.y) {
                StartCoroutine (buttonAnim ());
            }
        }
    }

as you can see i didn’t have to invert my .y component and it worked great for making a button on a mobile setting without using gui (LB,RB,TB,BB stands for left-bracket,right-bracket,top-bracket,bottom-bracket which are aligned respectively ex: left-bracket is a empty gameobject aligned with the furthest left side of the button image, etc.)

5

Maybe it’s works, but you unnecessarily complicates code. How you show button? You use GUI.Button or GameObject on scene? What he have to do - load next scene or turn on run?

To testing your app you need to set SDK settings - look on forum, there are many topics about this.

6

Hi I have the bug were when I use touch.deltatime it swipes different on higher resolutions. How can I fix this?