Quaternion.SetLookRotation

Parameters

Description

Creates a rotation with the specified forward and upwards directions.

Modifies the current quaternion to have the specified forward and upwards directions.

This method updates the existing quaternion in place, unlike Quaternion.LookRotation which returns a new quaternion. If used to orient a Transform, the Z axis is aligned with the forward direction vector and the Y axis with the upwards direction vector, assuming these vectors are orthogonal. Logs an error if the forward direction is zero.

Additional resources: LookRotation.

using UnityEngine;

// This example demonstrates the SetLookRotation method,
// and describes its key difference from the LookRotation method.
public class Quaternions : MonoBehaviour
{
    void Start()
    {        
        Vector3 direction = Vector3.right;

        // Method 1: LookRotation - a static method that created a new quaternion
        Quaternion newRotation = Quaternion.LookRotation(direction);
        Debug.Log($"LookRotation creates new: {newRotation}");

        // Method 2: SetLookRotation - an instance method that modifies an existing quaternion
        Quaternion existingRotation = Quaternion.identity;
        Debug.Log($"Before SetLookRotation: {existingRotation}");
        // Modifies in place
        existingRotation.SetLookRotation(direction); 
        Debug.Log($"After SetLookRotation:  {existingRotation}");

        // Both produce the same result, but use different approaches:
        Debug.Log($"Results are equal: {newRotation.Equals(existingRotation)}");

        // Usage patterns:
        // LookRotation: direct assignment
        transform.rotation = Quaternion.LookRotation(direction);

        // SetLookRotation: modify then assign
        Quaternion rotation = transform.rotation;
        rotation.SetLookRotation(direction);
        transform.rotation = rotation;
    }
}