Eliminating touch lag in mobile drag aiming with the New Input System

Enable EnhancedTouchSupport for robust finger tracking

Polling Touchscreen.current.touches in Update frequently drops phases or swaps indexes during multi-touch gestures. EnhancedTouchSupport provides stable Finger handles and event callbacks that lock onto the primary touch until release.

using UnityEngine;
using UnityEngine.InputSystem.EnhancedTouch;
using Touch = UnityEngine.InputSystem.EnhancedTouch.Touch;

public class DragAimController : MonoBehaviour
{
    private Finger activeFinger;

    private void OnEnable()
    {
        EnhancedTouchSupport.Enable();
        TouchSimulation.Enable();
        Touch.onFingerDown += HandleFingerDown;
        Touch.onFingerUp += HandleFingerUp;
    }

    private void OnDisable()
    {
        Touch.onFingerDown -= HandleFingerDown;
        Touch.onFingerUp -= HandleFingerUp;
        EnhancedTouchSupport.Disable();
    }

    private void HandleFingerDown(Finger finger)
    {
        if (activeFinger == null)
            activeFinger = finger;
    }

    private void HandleFingerUp(Finger finger)
    {
        if (activeFinger == finger)
            activeFinger = null;
    }
}

Fix the Z distance in ScreenToWorldPoint

Calling ScreenToWorldPoint with z=0 projects the position onto the camera near plane. In 2D orthographic games, pass -camera.transform.position.z as the vector Z coordinate to accurately map to the gameplay plane.

using UnityEngine;
using UnityEngine.InputSystem.EnhancedTouch;

public class AimWorldProjector : MonoBehaviour
{
    [SerializeField] private Camera targetCamera;

    public Vector2 GetWorldTouchPosition(Finger finger)
    {
        if (finger == null || finger.currentTouch.history.Count == 0)
            return Vector2.zero;

        Vector2 screenPos = finger.screenPosition;
        float distanceToPlane = -targetCamera.transform.position.z;
        Vector3 worldPoint = targetCamera.ScreenToWorldPoint(
            new Vector3(screenPos.x, screenPos.y, distanceToPlane)
        );
        return worldPoint;
    }
}

Enable Editor mouse simulation

Calling TouchSimulation.Enable() lets mouse clicks behave identically to touch events in the Unity Editor, accelerating aiming and trajectory tuning without device deploys.