Drag and rotate object similarly to Monument Valley rotation mechanics?

Questions & Answers
1

Hello everybody,

I’ve been trying to get an object to rotate just as the drag event works in Monument Valley. Here’s an example (skip to 0:13) youtube vid

Also if you happen to own Monument Valley, check Chapter 7 (“The Rookery”), that way you will instantly understand the type of rotation-movement I want to achieve.

So far I’ve tried a lot of things I found on other people’s questions & topics but just can’t get it to work right. Also I’m trying to get it work with the Void OnMouseDrag (). Asking for help here is literally the last thing I have left.

Not sure what else I should say regarding this, my so far Unity knowledge isn’t enough to figure this out by my own. Here’s also the code I last tried. If you feel like helping me then thank you in advance.

Edit: Google Drive link
did a quick project, try to rotate the object from bottom->Right->Top, it will stop halfway and then rotate backwards. If you constantly drag on the X axis it will keep rotating though which is also wrong. On MV, it works just fine when you do a full circle.

Hopefully the last edit: Here’s the final script Pastebin Link

using UnityEngine;
using System.Collections;
 
public class DragRotateX : MonoBehaviour
{
 
    public int speed;
    public float friction;
    public float xDeg;
    public float yDeg;
    public float zDeg;
    Quaternion fromRotation;
    Quaternion toRotation;
 
  void OnMouseDrag()
     {
          yDeg += Input.GetAxis ("Mouse Y") * speed * friction;
          xDeg -= Input.GetAxis ("Mouse X") * (Mathf.Cos (yDeg/60)*speed);
          transform.eulerAngles = new Vector3(yDeg,xDeg,zDeg);     
     }
  
}
3

Hey @PictonicSudio, I’d like to use your script but the math is beyond me, if I were to attempt to alter the axis that it operates on (i.e. to x or z) what would I change in this script? Furthermore, is it possible to make it work even when the object is viewed from the “bottom” (opposite side) without generating the rotation in opposite direction?

2

Try this script instead :slight_smile:

    private Quaternion originalRotation;
    private float startAngle = 0;

    public void Start()
    {
        originalRotation = this.transform.rotation;
    }
    public void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            MouseDown();
        }
        if (Input.GetMouseButton(0))
        {
            MouseHeld();
        }
    }

    public void MouseDown()
    {
        originalRotation = this.transform.rotation;
        Vector3 screenPos = Camera.main.WorldToScreenPoint(transform.position);
        Vector3 vector = Input.mousePosition - screenPos;
        startAngle = Mathf.Atan2(vector.y, vector.x) * Mathf.Rad2Deg;
    }

    public void MouseHeld()
    {
        Vector3 screenPos = Camera.main.WorldToScreenPoint(transform.position);
        Vector3 vector = Input.mousePosition - screenPos;
        float angle = Mathf.Atan2(vector.y, vector.x) * Mathf.Rad2Deg;
        Quaternion newRotation = Quaternion.AngleAxis(angle - startAngle, this.transform.up);
        newRotation.z = 0; 
        newRotation.eulerAngles = new Vector3(0, -newRotation.eulerAngles.y, 0);
        this.transform.rotation = originalRotation * (newRotation);
    }