unityQuaternionCoroutine.cs

using UnityEngine;
using System.Collections;

public class RotateCar : MonoBehaviour {

	public GameObject car;
	public GameObject doorLeft;
	public GameObject doorRight;

	private float rotateInc = 45.0f;
	private Quaternion destRotation;

	private Quaternion leftDoorOpenQuat = Quaternion.Euler(270, 237, 0);
	private Quaternion leftDoorClosedQuat;

	private Quaternion rightDoorOpenQuat = Quaternion.Euler(90, -60, 0);
	private Quaternion rightDoorClosedQuat;

	private float smoothing = 7f;
	private bool leftDoorOpen = false;
	private bool rightDoorOpen = false;

	private Quaternion doorLeftClosed;
	private Quaternion doorRightClosed;

	private IEnumerator carCoroutine;
	private IEnumerator leftDoorCoroutine;
	private IEnumerator rightDoorCoroutine;

	// Use this for initialization
	void Start () {

		leftDoorClosedQuat = doorLeft.transform.localRotation;
		rightDoorClosedQuat = doorRight.transform.localRotation;
	
	}
	
	// Update is called once per frame
	void Update () {

		if(Input.GetKeyDown(KeyCode.Space)) {
			destRotation = Quaternion.Euler(0, destRotation.eulerAngles.y+rotateInc, 0);

			if (carCoroutine != null) StopCoroutine(carCoroutine);

			carCoroutine = rotateTo(car.transform, destRotation);
			StartCoroutine(carCoroutine);
		}

		if(Input.GetKeyDown(KeyCode.LeftArrow)) {

			if (!leftDoorOpen) {
				
				if (leftDoorCoroutine != null) StopCoroutine(leftDoorCoroutine);
			
				leftDoorCoroutine = rotateTo(doorLeft.transform, leftDoorOpenQuat);
				StartCoroutine(leftDoorCoroutine);
				leftDoorOpen = true;

			} else {
				
				if (leftDoorCoroutine != null) StopCoroutine(leftDoorCoroutine);

				leftDoorCoroutine = rotateTo(doorLeft.transform, leftDoorClosedQuat);
				StartCoroutine(leftDoorCoroutine);
				leftDoorOpen = false;
			}
		}

		if(Input.GetKeyDown(KeyCode.RightArrow)) {

			if (!rightDoorOpen) {

				if (rightDoorCoroutine != null) StopCoroutine(rightDoorCoroutine);

				rightDoorCoroutine = rotateTo(doorRight.transform, rightDoorOpenQuat);
				StartCoroutine(rightDoorCoroutine);
				rightDoorOpen = true;

			} else {

				if (rightDoorCoroutine != null) StopCoroutine(rightDoorCoroutine);

				rightDoorCoroutine = rotateTo(doorRight.transform, rightDoorClosedQuat);
				StartCoroutine(rightDoorCoroutine);
				rightDoorOpen = false;
			}
		}
	}

	IEnumerator rotateTo (Transform transform, Quaternion destRotation)
	{
		while(Quaternion.Angle(transform.localRotation, destRotation) > 0.1f)
		{
			transform.localRotation = Quaternion.Slerp(transform.localRotation, destRotation, smoothing * Time.deltaTime);
			yield return null;
		}
	}
}