Taken from Discord : (Unity) Touch Input Help

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There was a discussion on the Unity channel over on Discord which I think would be beneficial to be put on the forum.

Environment : Unity
Topic : Touch input query

Whats in scene : simple box at origin with below script attached.
Orthographic camera at Z -10 from origin.

the question I believe was how to track the first touch that was made on mobile and ignore all others to then move a player. until all other fingers are lifted and the initial press once more sets the destination again.

I have had a play around this morning and got a little test sandbox, have a look rip it apart and see if any of the touch info helps, ive tried to comment as best I could in a rush.

the other stuff was just me playing around to get something working quickly as possible as I dont have the rest of your code. So have a look at the touch stuff and see if that helps any.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class TouchToMove : MonoBehaviour {

public float 	playerMoveSpeed	 = 2f; 	// used for the move towards later on
private int 		m_FingerIdTracker;			// this will be to track id of finger that is down

void Update () {
	// do we have more than one touch on screen?
	if (Input.touchCount > 0)
		DoTouchControlStuff();
}


void DoTouchControlStuff()
{
	// get the touch info for the first touch that hit the screen and store it
	Touch myTouch = Input.GetTouch(0);

	// now lets get the unique finger ID for that touch,
	// only if it has just began, AND theres only one touch hitting the screen
	if(myTouch.phase == TouchPhase.Began && Input.touchCount == 1)
	{
		m_FingerIdTracker = myTouch.fingerId;
		Debug.Log("new id set as new single touch detected");
	}

	// since we know that our fingerid was only for that first press, lets compare it to the frst one thats
	// currently on the screen, just in case you lift 1st finger and leave 2nd on.
	if(myTouch.fingerId == m_FingerIdTracker)
	{
		// if its the same, great, now move our player around
		MoveTowardsInScreenSpace(myTouch.position);
	}
}


void MoveTowardsInScreenSpace(Vector2 cursorPos)
{
	// move player based on the cursorPos which is the 2d position in screen space of the touch were using
	// just using a simple 2d view here to illustrate with the player
	// create ray
	Ray ray = Camera.main.ScreenPointToRay(cursorPos);
	// create the aim plane
	Plane groundPlane = new Plane (
		// just need to declare 3 corner points to create the plane, as it iterpolates the 4th corner.
		// doing it this way, creates the plane dead centre of the ball
		new Vector3(transform.position.x + 10f, transform.position.y-10f, transform.position.z),
		new Vector3(transform.position.x - 10f, transform.position.y-10f, transform.position.z),
		new Vector3(transform.position.x + 10f, transform.position.y+10f, transform.position.z));
	// used for raycasting out, logs hit distance
	float rayDistance;

	if(groundPlane.Raycast(ray, out rayDistance))
	{
		Vector3 destinationPosition = ray.GetPoint(rayDistance);
		// lock the Y and Z positions
		destinationPosition.z = transform.position.z;
		destinationPosition.y = transform.position.y;

		transform.position = Vector3.MoveTowards(transform.position, destinationPosition,Time.deltaTime * playerMoveSpeed);
	}
}

}

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