How to rotate a line by its other end at runtime?

Question

So basically i want to rotate a line by its other end. More clearly, i draw one straight line which is 10x1 long. I want to grab one of its end with the mouse and than it would rotate around its other ends positions. Is this possible?

Answer 1

Here is a short script I made that accomplishes what I think you are asking for. Keep track of the ends of the line with two points and just use Camera.ScreenToWorldPoint(Input.mousePosition) to rotate the points. If this doesn't do what you want it should at least give you an idea of what you need to do.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class DisRotTest : MonoBehaviour
 {
 
     public Transform point1, point2;
     public Camera cam;
 
     private LineRenderer lr;
     private Transform grabbedPoint, stationaryPoint;
     private Vector3[] lrPoints;
     void Start()
     {
         //Set the initial line length to 10
         point2.position = point1.position + 10 * Vector3.up;
 
         //I'm using a line renderer to draw the line
         lr = GetComponent<LineRenderer>();
         lrPoints = new Vector3[2];
 
         //Tell the line renderer to update its points
         SetLinePoints();
 
         grabbedPoint = stationaryPoint = null;
     }
 
     private void Update()
     {
         //Grab mouse position every frame
         Vector3 mousePos = cam.ScreenToWorldPoint(Input.mousePosition);
 
         //I want to rotate on the X-Y plane, so I'm going to align the mousePosition with my gameObject on the Z axis
         mousePos.z = transform.position.z;
 
         //When we click, grab the closest point
         if (Input.GetMouseButtonDown(0))
         {
             grabbedPoint = Vector3.Distance(mousePos, point1.position) < Vector3.Distance(mousePos, point2.position) ? point1 : point2;
             stationaryPoint = grabbedPoint == point1 ? point2 : point1;
         }
 
         //While we drag, make the line go through our mouse position
         if (Input.GetMouseButton(0))
         {
             Vector3 offset = mousePos - stationaryPoint.position;
             offset = offset.normalized * 10; //Set line length to 10
             grabbedPoint.position = stationaryPoint.position + offset;
         }
 
         //Tell the line renderer to update
         SetLinePoints();
     }
 
     private void SetLinePoints()
     {
         lrPoints[0] = point1.position;
         lrPoints[1] = point2.position;
         lr.SetPositions(lrPoints);
     }
 }

How to rotate a line by its other end at runtime?

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