How to check if device has been rotated on all axis in Unity

Question

I want to check in Unity if the device has been rotated on all of it's axis. So, I am reading the rotation of all the axis.

What should I do in order to validate for example that the user has "flipped" his device over the X-axis? I need to check the value, and see that they contain 0, 90, 180 and 270 degrees in a loop.

Here is part of my code:

void Update () {

    float X = Input.acceleration.x;
    float Y = Input.acceleration.y;
    float Z = Input.acceleration.z;
    xText.text =  ((Mathf.Atan2(Y, Z) * 180 / Mathf.PI)+180).ToString();
    yText.text = ((Mathf.Atan2(X, Z) * 180 / Mathf.PI)+180).ToString();
    zText.text = ((Mathf.Atan2(X, Y) * 180 / Mathf.PI)+180).ToString();

}

Answer 1

The accelerometer only tells you if the acceleration of the device changes. So you will have values if the device started moving, or stopped moving. You can't retrieve its orientation from that.

Instead you need to use the gyroscope of the device. Most device have one nowadays.

Fortunately, Unity supports the gyroscope through the Gyroscope class

Simply using

Input.gyro.attitude

Will give you the orientation of the device in space, in the form of a quaternion.

To check the angles, use the eulerAngles function, for instance, is the device flipped in the x axis:

Vector3 angles = Input.gyro.attitude.eulerAngles;
bool xFlipped = angles.x > 180;

Be careful, you might have to invert some values if you want to apply the rotation in Unity (because it depend which orientation the devices uses for positive values, left or right)

// The Gyroscope is right-handed.  Unity is left handed.
// Make the necessary change to the camera.
private static Quaternion GyroToUnity(Quaternion q)
{
    return new Quaternion(q.x, q.y, -q.z, -q.w);
}

---

Here is the full example from the doc (Unity version 2017.3), in case the link above is broken. It shows how to read value from the gyroscope, and apply them to an object in Unity.

// Create a cube with camera vector names on the faces.
// Allow the device to show named faces as it is oriented.

using UnityEngine;

public class ExampleScript : MonoBehaviour
{
    // Faces for 6 sides of the cube
    private GameObject[] quads = new GameObject[6];

    // Textures for each quad, should be +X, +Y etc
    // with appropriate colors, red, green, blue, etc
    public Texture[] labels;

    void Start()
    {
        // make camera solid colour and based at the origin
        GetComponent<Camera>().backgroundColor = new Color(49.0f / 255.0f, 77.0f / 255.0f, 121.0f / 255.0f);
        GetComponent<Camera>().transform.position = new Vector3(0, 0, 0);
        GetComponent<Camera>().clearFlags = CameraClearFlags.SolidColor;

        // create the six quads forming the sides of a cube
        GameObject quad = GameObject.CreatePrimitive(PrimitiveType.Quad);

        quads[0] = createQuad(quad, new Vector3(1,   0,   0), new Vector3(0,  90, 0), "plus x",
                new Color(0.90f, 0.10f, 0.10f, 1), labels[0]);
        quads[1] = createQuad(quad, new Vector3(0,   1,   0), new Vector3(-90,   0, 0), "plus y",
                new Color(0.10f, 0.90f, 0.10f, 1), labels[1]);
        quads[2] = createQuad(quad, new Vector3(0,   0,   1), new Vector3(0,   0, 0), "plus z",
                new Color(0.10f, 0.10f, 0.90f, 1), labels[2]);
        quads[3] = createQuad(quad, new Vector3(-1,   0,   0), new Vector3(0, -90, 0), "neg x",
                new Color(0.90f, 0.50f, 0.50f, 1), labels[3]);
        quads[4] = createQuad(quad, new Vector3(0,  -1,  0), new Vector3(90,   0,  0), "neg y",
                new Color(0.50f, 0.90f, 0.50f, 1), labels[4]);
        quads[5] = createQuad(quad, new Vector3(0,   0, -1), new Vector3(0, 180,  0), "neg z",
                new Color(0.50f, 0.50f, 0.90f, 1), labels[5]);

        GameObject.Destroy(quad);
    }

    // make a quad for one side of the cube
    GameObject createQuad(GameObject quad, Vector3 pos, Vector3 rot, string name, Color col, Texture t)
    {
        Quaternion quat = Quaternion.Euler(rot);
        GameObject GO = Instantiate(quad, pos, quat);
        GO.name = name;
        GO.GetComponent<Renderer>().material.color = col;
        GO.GetComponent<Renderer>().material.mainTexture = t;
        GO.transform.localScale += new Vector3(0.25f, 0.25f, 0.25f);
        return GO;
    }

    protected void Update()
    {
        GyroModifyCamera();
    }

    protected void OnGUI()
    {
        GUI.skin.label.fontSize = Screen.width / 40;

        GUILayout.Label("Orientation: " + Screen.orientation);
        GUILayout.Label("input.gyro.attitude: " + Input.gyro.attitude);
        GUILayout.Label("iphone width/font: " + Screen.width + " : " + GUI.skin.label.fontSize);
    }

    /********************************************/

    // The Gyroscope is right-handed.  Unity is left handed.
    // Make the necessary change to the camera.
    void GyroModifyCamera()
    {
        transform.rotation = GyroToUnity(Input.gyro.attitude);
    }

    private static Quaternion GyroToUnity(Quaternion q)
    {
        return new Quaternion(q.x, q.y, -q.z, -q.w);
    }
}