how to smoothly rotate an object to inverse direction

Questions & Answers
1

how can I smoothly rotate an object to inverse direction?
Here is what I put together when trying to solve the problem. (However my guy never turns around…)

Also, how I can I check and see when I have successfully turned around.

function TurnAround()
{
    if(needInverse)
	{
        //Get the opposite rotation needed.
        rotArd = Quaternion.Inverse(transform.rotation);	
		needInverse = false;
	}	
	//Rotate back.
	transform.rotation = Quaternion.Slerp(transform.rotation, rotArd, 1);
	if(rotArd == transform.rotation)
	{
		//Finished turning around.
		turnAround = false;
		isPickDir = true;
		needInverse = true;
	}
}
2

Quaternion.Inverse(transform.rotation) creates a rotation to make the character return to the orientation it was created or imported - I suspect that this isn’t what you want.

If you want a function to rotate some angle lower than 180, you can use Quaternion.RotateTowards in a coroutine like this:

var speed: float = 60; // speed in degrees per second
var turning: boolean = false; // this is true while turning

function TurnAngle(angle: float){

  if (!turning){ // don't start another rotation while this one is running
    turning = true; // tells that this rotation is running
    var degrees = Mathf.Abs(angle); // calculate degrees to rotate
    var dest = Quaternion.Euler(0, angle, 0) * transform.rotation;
    while (degrees > 0){
      var dt = speed*Time.deltaTime;
      // rotate dt degrees this frame
      transform.rotation = Quaternion.RotateTowards(transform.rotation, dest, dt);
      degrees -= dt; // subtract the angle rotated this frame
      yield; // let Unity free till the next frame
    }
    turning = false; // tells that rotation finished
  }
}

RotateTowards goes in the shortest direction, thus for angles < -180 or > 180 the object will rotate in the opposite direction, and for exactly 180 or -180, the object may rotate around weird axes due to a quaternion problem that I call “South Pole Madness”. If you need to rotate to 180, for instance, call TurnAngle(90) two times in another coroutine, waiting turning become false before each call - like this:

function Turn180(){
    while (turning) yield;
    TurnAngle(90);
    while (turning) yield;
    TurnAngle(90);
}
3

Im using this for invert Input.gyro.attitude quaternion
but I have to work with Vector3 and them invert rotate

basicly I do that:

Vector3 rotation = quaternionAngle.eulerAngles ;
rotation.x *= -1 ;
rotation.y *= -1 ;
Quaternion quaternionInverted = Quaternion.Euler( rotation ) ;

look the class:

using UnityEngine;
using System.Collections;

public class DevicePosition {

// Use this for initialization
public static void start () {
	Input.gyro.enabled = true;
}

// Update is called once per frame
public static Vector3 getVector () {
	Vector3 rotation = Input.gyro.attitude.eulerAngles ;
	rotation.x *= -1 ;
	rotation.y *= -1 ;
	return rotation ;
}
public static Quaternion getQuaternion(){
	return Quaternion.Euler ( DevicePosition.getVector() ) ;
}

}