Rotate Bar Based on Touch Drag - unity3d

Question

I want to rotate the bar based on my finger touch draw related to the pivot point. Following test structure implementation, I have created it for testing purposes.
Currently, I can able to write this code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class TestRotateController : MonoBehaviour
{
float rotateSpeed = 10f;
Vector2 touchStartPos;
Transform touchItem;
//
[SerializeField] LayerMask touchItemsMask;
private void Update()
{
if (Input.GetMouseButtonDown(0))
{
Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
Vector2 mousePos2D = new Vector2(mousePos.x, mousePos.y);
RaycastHit2D hit = Physics2D.Raycast(mousePos2D, Vector2.zero, 0f, touchItemsMask);
if (hit.collider != null && hit.transform.CompareTag(GameConstants.TAG_RELEASE_ANGLE_BAR))
{
touchItem = hit.transform;
touchStartPos = mousePos2D;
}
}
else if (Input.GetMouseButton(0))
{
if (touchItem != null && touchItem.CompareTag(GameConstants.TAG_RELEASE_ANGLE_BAR))
{
Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
Vector2 mousePos2D = new Vector2(mousePos.x, mousePos.y);
RotateReleaseAngleBar(touchStartPos, mousePos2D);
}
}
else if (Input.GetMouseButtonUp(0))
{
touchItem = null;
}
}
// rotate pivot parent
public void RotateReleaseAngleBar(Vector2 touchStartPosition, Vector2 touchPosition)
{
if (touchStartPosition.x > touchPosition.x)
{
transform.parent.Rotate(Vector3.forward, rotateSpeed * Time.deltaTime);
}
else if (touchStartPosition.x < touchPosition.x)
{
transform.parent.Rotate(Vector3.forward, -rotateSpeed * Time.deltaTime);
}
}
}
Now with this code, I can't able to rotate the bar as my finger is moving.
Selected direction will remain proper because I have used X value to decide this but when I stop dragging my finger then also rotation remain continue in the same direction.
I want to stop this, I want to rotate the bar based on finger drag amount. It is a kind of experience, I want a person is rotating the bar with his finger.

Answer 1

I think you don't really want to rotate the bar by a certain amount each frame, but instead update its rotation at each frame with respect to the finger.
You are currently rotating the bar not considering the exact (x,y) mouse2D position of current frame, which is what you need.
This script works for me, assuming you assign it to the child of the pivot (as I assume you did from the screenshot)
public class TestRotateController : MonoBehaviour
{
//member variables
void Update() {
//[...] take the input as you did...
//else
if (Input.GetMouseButton(0)) {
//if(touchItem != null...) {
Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
Vector2 mousePos2D = new Vector2(mousePos.x, mousePos.y);
RotateFollowPoint(mousePos2D);
//}
}
//[else...]
}
//sets the angle of the bar to point in the direction of targetPoint2D
void RotateFollowPoint(Vector2 targetPoint2D) {
Vector2 position2D = new Vector2(transform.parent.position.x, transform.parent.position.y);
float angle = Vector2.Angle(Vector2.right, targetPoint2D - position2D);
if (targetPoint2D.y < position2D.y)
angle *= -1;
transform.parent.eulerAngles = new Vector3(0, 0, angle);
}
}
First you take the position 2D of the pivot point, then you compute the acute angle between the vector pointing from the pivot to the clicked point, which is targetPoint2D - position2D, and the Vector2.right vector (which is (1,0), so a vector pointing right), which means that the bar must be oriented to the right on its default position (when rotation on Z of the pivot = 0).
Then since Vector2.Angle gives the acute angle, set it negative if it should be more than 180°, and finally just update the angle accordingly