CODEWITHSUNDEEP
c#unity-game-enginerotationquaternions
Larsus
Larsus

Reputation: 111

How to rotate an object around itself?

I want to rotate a cube in Unity3D.When I push arrow left button on keyboard the cube have to rotate left.If I push up, the cube have to rotate up.But with my script the cube rotate left and then the left-side rotate up.

This is the current status:

enter image description here

That's what I want:

enter image description here

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Rotate : MonoBehaviour
{
    public float smooth = 1f;
    private Quaternion targetRotation;
    // Start is called before the first frame update
    void Start()
    {
        targetRotation = transform.rotation;
    }

    // Update is called once per frame
    void Update()
    {
        if(Input.GetKeyDown(KeyCode.UpArrow)){
            targetRotation *= Quaternion.AngleAxis(90, Vector3.right);
        }
        if(Input.GetKeyDown(KeyCode.DownArrow)){
            targetRotation *= Quaternion.AngleAxis(90, Vector3.left);
        }
        if(Input.GetKeyDown(KeyCode.LeftArrow)){
            targetRotation *= Quaternion.AngleAxis(90, Vector3.up);
        }
        if(Input.GetKeyDown(KeyCode.RightArrow)){
            targetRotation *= Quaternion.AngleAxis(90, Vector3.down);
        }
        transform.rotation = Quaternion.Lerp(transform.rotation, targetRotation, 10* smooth * Time.deltaTime);

    }
}

Upvotes: 1

Views: 1584

Answers (1)

Ruzihm
Ruzihm

Reputation: 20270

You need to swap the order of your quaternion multiplication.

The way you have it now, the rotations are applied to the axes as they would be after the original rotation because you are effectively doing targetRotation = targetRotation * ...;.

However, you want to rotate the rotation around the world axes. You can do this by doing targetRotation = ... * targetRotation;:

void Update()
{
    if(Input.GetKeyDown(KeyCode.UpArrow)){
        targetRotation = Quaternion.AngleAxis(90, Vector3.right) * targetRotation;
    }
    if(Input.GetKeyDown(KeyCode.DownArrow)){
        targetRotation = Quaternion.AngleAxis(90, Vector3.left) * targetRotation;
    }
    if(Input.GetKeyDown(KeyCode.LeftArrow)){
        targetRotation = Quaternion.AngleAxis(90, Vector3.up) * targetRotation;
    }
    if(Input.GetKeyDown(KeyCode.RightArrow)){
        targetRotation = Quaternion.AngleAxis(90, Vector3.down) * targetRotation;
    }
    transform.rotation = Quaternion.Lerp(transform.rotation, targetRotation, 10* smooth * Time.deltaTime);

}

See How do I rotate a Quaternion with 2nd Quaternion on its local or world axes without using transform.Rotate? for more information.

Upvotes: 1

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