Two rotations at the same time, on the same axis.

Questions & Answers
1

I need help regarding two rotations at the same time, on the same axis. One vector is approaching 90 degrees. When I press up, it should smoothly approach the angle 45 degrees above it, such that HOLDING up will still be going down.
Here is a rough sketch of what I mean:
(black = vector without up,
red = vector approaching 45 above black)

184366-vectors-2.png
184366-vectors-2.png340×789 4.34 KB

2

Ok. As far as I can understand you are probably asking how to combine rotations

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

public class TwoRotations : MonoBehaviour
{

    Quaternion _main = Quaternion.identity;
    Quaternion _auxiliary = Quaternion.identity;
    Coroutine _coroutine = null;

    void Update ()
    {
        // animate main rotation every frame;
        _main = _main * Quaternion.AngleAxis( 10f*Time.deltaTime , transform.up );
        
        // animate auxiliary rotation on player input:
        if( Input.GetKey(KeyCode.UpArrow) )
        {
            if( _coroutine!=null ) StopCoroutine( _coroutine );
            _coroutine = StartCoroutine(
                AnimateAuxiliaryRotation( _auxiliary , Quaternion.Euler(0,45f,0) , 1.5f )
            );
        }
        if( Input.GetKey(KeyCode.DownArrow) )
        {
            if( _coroutine!=null ) StopCoroutine( _coroutine );
            _coroutine = StartCoroutine(
                AnimateAuxiliaryRotation( _auxiliary , Quaternion.Euler(0,0,0) , 1.5f )
            );
        }
        
        // combine rotations:
        transform.rotation = _main * _auxiliary;
    }

    IEnumerator AnimateAuxiliaryRotation ( Quaternion src , Quaternion dst , float duration )
    {
        float time = 0;
        do
        {
            _auxiliary = Quaternion.Slerp( src , dst , time/duration );
            time += Time.deltaTime;
            yield return null;
        }
        while( time < duration );
    }

}