Unity XR Input

This section of the Unity User Manual provides information about all of the Unity-supported input devices for virtual reality, augmented reality, and Windows Mixed Reality applications. This page covers the following topics:

• XR input mappings
• Accessing input devices
• Accessing input features on an input device
• Accessing XR input via the legacy input system
• Haptics

XR platforms have a rich variety of input features that you can take advantage of when you design user interactions. Your application can use specific data that references positions, rotations, touch, buttons, joysticks, and finger sensors. However, access to these input features can vary a lot between platforms. For instance, there are small differences between the Vive and the Oculus Rift, but a VR-enabled desktop platform and a mobile platform like Daydream differ a lot more.

Unity provides a C# struct called InputFeatureUsage, which defines a standard set of physical device controls (such as buttons and triggers) to access user input on any platform. These help you identify input types by name. See XR.Input.CommonUsages for a definition of each InputFeatureUsage.

Each InputFeatureUsage corresponds to a common input action or type. For example, Unity defines the InputFeatureUsage called trigger as a single-axis input that the index finger controls, regardless of which XR platform you use. You can use InputFeatureUsage to get the trigger state using its name, so you don’t need to set up an axis (or a button on some XR platforms) for the conventional Unity Input system.

XR input mappings

The following table lists the standard controller InputFeatureUsage names and how they map to the controllers of popular XR systems:

(1) Sandwich button refers to the Vive menu button. This button is mapped to primaryButton, rather than menuButton, in order to better handle cross-platform applications.

See XR.Input.CommonUsages for a definition of each InputFeatureUsage.

Accessing input devices

An InputDevice represents any physical device, such as a controller, mobile phone, or headset. It can contain information about device tracking, buttons, joysticks, and other input controls. For more information on the InputDevice API, see documentation on InputDevice.

Use the XR.InputDevices class to access input devices that are currently connected to the XR system. To get a list of all connected devices, use InputDevices.GetDevices:

var inputDevices = new List<UnityEngine.XR.InputDevice>();
UnityEngine.XR.InputDevices.GetDevices(inputDevices);

foreach (var device in inputDevices)
{
    Debug.Log(string.Format("Device found with name '{0}' and role '{1}'", device.name, device.role.ToString()));
}

An input device remains valid across frames until the XR system disconnects it. Use the InputDevice.IsValid property to determine whether an InputDevice still represents an active controller.

You can access input devices by:

• Characteristics
• Role
• XR node

Accessing input devices by characteristics

Device characteristics describe what a device is capable of, or what it’s used for (for example, whether it is head-mounted). The InputDeviceCharacteristics is a series of flags you can add to your code to search for devices that fit a certain specification. You can filter devices by the following characteristics:

Device	Characteristic
HeadMounted	The device is attached to the user’s head. It has device tracking and center eye tracking. This flag is most commonly used to identify head-mounted displays (HMDs).
Camera	The device has camera tracking.
HeldInHand	The user holds the device in their hand.
HandTracking	The device represents a physically-tracked hand. It has device tracking, and might contain hand and bone data.
EyeTracking	The device can perform eye tracking and has an EyesData feature.
TrackedDevice	The device can be tracked in 3D space. It has device tracking.
Controller	The device has input data for buttons and axes, and can be used as a controller.
TrackingReference	The device represents a static tracking reference object. It has device tracking, but that tracking data shouldn’t change.
Left	Use this characteristic in combination with the HeldInHand or HandTracking characteristics to identify the device as associated with the left hand.
Right	Use this characteristic in combination with the HeldInHand or HandTracking characteristics to identify the device as associated with the right hand.
Simulated6DOF	The device reports 6DOF data, but only has 3DOF sensors. Unity simulates the positional data.

The underlying XR SDK reports these characteristics. You can look them up with InputDevice.Characteristics. A device can, and often should, have multiple characteristics that you can filter and access with bit flags.

InputDevices.GetDevicesWithCharacteristics provides a way to search for all devices with a given set of characteristics. For example, you can search for Left, HeldInHand, Controller InputDevices available in the system with the following code:

var leftHandedControllers = new List<UnityEngine.XR.InputDevice>();
var desiredCharacteristics = UnityEngine.XR.InputDeviceCharacteristics.HeldInHand | UnityEngine.XR.InputDeviceCharacteristics.Left | UnityEngine.XR.InputDeviceCharacteristics.Controller;
UnityEngine.XR.InputDevices.GetDevicesWithCharacteristics(desiredCharacteristics, leftHandedControllers);

foreach (var device in leftHandedControllers)
{
    Debug.Log(string.Format("Device name '{0}' has characteristics '{1}'", device.name, device.characteristics.ToString()));
}

Devices this function finds contain at least the characteristics specified, but might contain additional characteristics. For example, to find a left handed controller you can look for InputDeviceCharacteristic.Left only, and not InputDeviceCharacteristic.Controller.

Accessing input devices by role

A device role describes the general function of an input device. Use the InputDeviceRole enumeration to specify a device role. The defined roles are:

Role	Description
GameController	A console-style game controller.
Generic	A device that represents the core XR device, such as a head-mounted display or mobile device.
HardwareTracker	A tracking device.
LeftHanded	A device associated with the user’s left hand.
RightHanded	A device associated with the user’s right hand.
TrackingReference	A device that tracks other devices, such as an Oculus tracking camera.

The underlying XR SDK reports these roles, but different providers might organize their device roles differently. Additionally, a user can switch hands, so the role assignment might not match the hand in which the user holds the input device. For example, a user must set up the Daydream controller as right or left-handed, but can choose to hold the controller in their opposite hand.

GetDevicesWithRole provides a list of any devices with a specific InputDeviceRole. For example, you can use InputDeviceRole.GameController to get any connected GameController devices:

var gameControllers = new List<UnityEngine.XR.InputDevice>();
UnityEngine.XR.InputDevices.GetDevicesWithRole(UnityEngine.XR.InputDeviceRole.GameController, gameControllers);

foreach (var device in gameControllers)
{
    Debug.Log(string.Format("Device name '{0}' has role '{1}'", device.name, device.role.ToString()));
}

Accessing input devices by XR node

XR nodes represent the physical points of reference in the XR system (for example, the user’s head position, their right and left hands, or a tracking reference such as an Oculus camera).

The XRNode enumeration defines the following nodes:

XR node	Description
CenterEye	A point midway between the pupils of the user’s eyes.
GameController	A console-style game controller. Your app can have multiple game controller devices.
HardwareTracker	A hardware tracking device, typically attached to the user or a physical item. Multiple hardware tracker nodes can exist.
Head	The center point of the user’s head, as calculated by the XR system.
LeftEye	The user’s left eye.
LeftHand	The user’s left hand.
RightEye	The user’s right eye.
RightHand	The user’s right hand.
TrackingReference	A tracking reference point, such as the Oculus camera. Multiple tracking reference nodes can exist.

Use InputDevices.GetDevicesAtXRNode to get a list of devices associated with a specific XRNode. The following example demonstrates how to get a left-handed controller:

var leftHandDevices = new List<UnityEngine.XR.InputDevice>();
UnityEngine.XR.InputDevices.GetDevicesAtXRNode(UnityEngine.XR.XRNode.LeftHand, leftHandDevices);

if(leftHandDevices.Count == 1)
{
    UnityEngine.XR.InputDevice device = leftHandDevices[0];
    Debug.Log(string.Format("Device name '{0}' with role '{1}'", device.name, device.role.ToString()));
}
else if(leftHandDevices.Count > 1)
{
    Debug.Log("Found more than one left hand!");
}

Listening for device connections and disconnections

Input devices are consistent from frame to frame, but can connect or disconnect at any time. To avoid repeatedly checking if a device is connected to the platform, use InputDevices.deviceConnected and InputDevices.deviceDisconnected to notify your application when a device connects or disconnects. These also provide you with a reference to the newly connected input device.

Since you can retain these references over multiple frames, a device might disconnect, or is otherwise no longer available. To check if a device’s inputs are still available, use InputDevice.isValid. Scripts that access input devices should check this at the start of each frame before they attempt to use that device.

Accessing input features on an input device

You can read an input feature, such as the state of a trigger button, from a specific InputDevice. For example, to read the state of the right trigger, follow these steps:

1. Use InputDeviceRole.RightHanded or XRNode.RightHand to get an instance of the right-handed device.
2. Once you have the correct device, use the InputDevice.TryGetFeatureValue method to access the current state.

TryGetFeatureValue() attempts to access the current value of a feature, and returns:

• true if it successfully retrieves the specified feature value
• false if the current device doesn’t support the specified feature, or the device is invalid (that is, the controller is no longer active)

To get a particular button, touch input, or joystick axis value, use the CommonUsages class. CommonUsages includes each InputFeatureUsage in the XR input mapping table, as well as tracking features like position and rotation. The following code example uses CommonUsages.triggerButton to detect whether the user is currently pressing the trigger button on a particular InputDevice instance:

bool triggerValue;
if (device.TryGetFeatureValue(UnityEngine.XR.CommonUsages.triggerButton, out triggerValue) && triggerValue)
{
    Debug.Log("Trigger button is pressed.");
}

You can also use the InputDevice.TryGetFeatureUsages method to get a list of every InputFeatureUsage that a device provides. This function returns a list of InputFeatureUsage items, which have a type and a name property that describes the feature. The following example enumerates all of the Boolean features that a given input device provides:

var inputFeatures = new List<UnityEngine.XR.InputFeatureUsage>();
if (device.TryGetFeatureUsages(inputFeatures))
{
    foreach (var feature in inputFeatures)
    {
        if (feature.type == typeof(bool))
        {
            bool featureValue;
            if (device.TryGetFeatureValue(feature.As<bool>(), out featureValue))
            {
                Debug.Log(string.Format("Bool feature {0}'s value is {1}", feature.name, featureValue.ToString()));
            }
        }
    }
}

Example for primaryButton

Different controller configurations provide access to different features. For example, you might have multiple controllers on one system, different controllers on different systems, or different buttons on the same controllers with different SDKs. This diversity makes it more complicated to support input from a range of XR systems. The Unity InputFeatureUsage API helps you get input that isn’t platform-dependent.

The following example accesses the InputFeatureUsage called primaryButton, no matter which controller or input device provides it. The example includes a class that scans the available devices for the primaryButton as they connect. The class monitors the value of the feature on any connected device and, if the value changes, the class dispatches a UnityEvent.

To use this class, add it as a component to any GameObject in the Scene. For example:

using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.XR;

[System.Serializable]
public class PrimaryButtonEvent : UnityEvent<bool> { }

public class PrimaryButtonWatcher : MonoBehaviour
{
    public PrimaryButtonEvent primaryButtonPress;

    private bool lastButtonState = false;
    private List<InputDevice> devicesWithPrimaryButton;

    private void Awake()
    {
        if (primaryButtonPress == null)
        {
            primaryButtonPress = new PrimaryButtonEvent();
        }

        devicesWithPrimaryButton = new List<InputDevice>();
    }

    void OnEnable()
    {
        List<InputDevice> allDevices = new List<InputDevice>();
        InputDevices.GetDevices(allDevices);
        foreach(InputDevice device in allDevices)
            InputDevices_deviceConnected(device);

        InputDevices.deviceConnected += InputDevices_deviceConnected;
        InputDevices.deviceDisconnected += InputDevices_deviceDisconnected;
    }

    private void OnDisable()
    {
        InputDevices.deviceConnected -= InputDevices_deviceConnected;
        InputDevices.deviceDisconnected -= InputDevices_deviceDisconnected;
        devicesWithPrimaryButton.Clear();
    }

    private void InputDevices_deviceConnected(InputDevice device)
    {
        bool discardedValue;
        if (device.TryGetFeatureValue(CommonUsages.primaryButton, out discardedValue))
        {
            devicesWithPrimaryButton.Add(device); // Add any devices that have a primary button.
        }
    }

    private void InputDevices_deviceDisconnected(InputDevice device)
    {
        if (devicesWithPrimaryButton.Contains(device))
            devicesWithPrimaryButton.Remove(device);
    }

    void Update()
    {
        bool tempState = false;
        foreach (var device in devicesWithPrimaryButton)
        {
            bool primaryButtonState = false;
            tempState = device.TryGetFeatureValue(CommonUsages.primaryButton, out primaryButtonState) // did get a value
                        && primaryButtonState // the value we got
                        || tempState; // cumulative result from other controllers
        }

        if (tempState != lastButtonState) // Button state changed since last frame
        {
            primaryButtonPress.Invoke(tempState);
            lastButtonState = tempState;
        }
    }
}

The following PrimaryReactor class uses the PrimaryButtonWatcher to detect when you press a primary button and, in response to a press, rotates its parent GameObject. To use this class, add it to a visible GameObject, such as a Cube, and drag the PrimaryButtonWatcher reference to the Watcher property.

using System.Collections;
using UnityEngine;

public class PrimaryReactor : MonoBehaviour
{
    public PrimaryButtonWatcher watcher;
    public bool IsPressed = false; // used to display button state in the Unity Inspector window
    public Vector3 rotationAngle = new Vector3(45, 45, 45);
    public float rotationDuration = 0.25f; // seconds
    private Quaternion offRotation;
    private Quaternion onRotation;
    private Coroutine rotator;

    void Start()
    {
        watcher.primaryButtonPress.AddListener(onPrimaryButtonEvent);
        offRotation = this.transform.rotation;
        onRotation = Quaternion.Euler(rotationAngle) * offRotation;
    }

    public void onPrimaryButtonEvent(bool pressed)
    {
        IsPressed = pressed;
        if (rotator != null)
            StopCoroutine(rotator);
        if (pressed)
            rotator = StartCoroutine(AnimateRotation(this.transform.rotation, onRotation));
        else
            rotator = StartCoroutine(AnimateRotation(this.transform.rotation, offRotation));
    }

    private IEnumerator AnimateRotation(Quaternion fromRotation, Quaternion toRotation)
    {
        float t = 0;
        while (t < rotationDuration)
        {
            transform.rotation = Quaternion.Lerp(fromRotation, toRotation, t / rotationDuration);
            t += Time.deltaTime;
            yield return null;
        }
    }
}

Accessing hand-tracking data

InputDevices support hand-tracking devices. A hand-tracking device always:

• has the HandTracking characteristic
• contains a CommonUsages.HandData usage of the Hand type

Hand-tracking data consists of a Hand object and a series of up to 21 Bone input features. Each Bone has a position and orientation, as well as references to both its parent and any child bones in the hierarchy. The Hand object can get either the root bone, or a list of bones for each individual finger.

When Hand.TryGetRootBone gets the root bone, it retrieves an object that represents a bone located just above the wrist. You can also get a list of bones that represents each individual finger. Calling Hand.TryGetFingerBones returns a list, from knuckle to tip, of the bones that represents that finger.

Accessing eye-tracking data

Input devices support eye-tracking devices, as well as hand-tracking devices. Eye-tracking consists of the left and right eye positions, the location in 3D space where the user is looking, and the amount that each individual eye is blinking. Its data type is Eyes. To retrieve it from a device, use CommonUsages.eyesData.

XRInputSubsystem and InputDevice association

Unity provides two input systems: the legacy input system, and the XR plugin architecture introduced in 2019.2. In the new setup, each InputDevice is associated with an XRInputSubsystem. These subsystem objects control global input behavior that isn’t associated with any specific input device (for example, managing the tracking origin, or recentering tracked devices).

Each InputDevice contains a reference to its associated subsystem. This reference is null if the device comes from an integrated platform. You can also get all active XRInputSubsystem objects with SubsystemManager.GetInstances<XRInputSubsystem>, and each XRInputSubsystem can get its devices with XRInputSubsystem.TryGetInputDevices.

You can use the Input Subsystem to recenter devices with UnityEngine.XR.XRInputSubsystem. Recenter sets the current position of the HMD as the new origin for all devices. It returns false for devices that can’t be recentered, or if the platform doesn’t support recentering.

To retrieve the tracking boundary, use TryGetBoundaryPoints. This consists of a series of clockwise-ordered 3D points, where the y-value is at floor level, and they mark out the user-specified ‘safe zone’ to place content and interactions. You can listen for changes to this boundary with XRInputSubsystem.boundaryChanged.

The XRInputSubsystem is also responsible for the tracking origin mode, which provides context for where the origin of the tracking world is. Unity supports the following tracking origin modes:

• Device: The origin’s location is at the first known location of the primary display device; often an HMD or a phone.
• Floor: The origin’s location is at a known location on the floor.
• Tracking Reference: The origin’s location is on an InputDevice with the TrackingReference characteristic set.
• Unknown: The type of tracking origin is unknown. This can be because of a system failure or lack of tracking origin-mode support.

There are three APIs you can use to manage the tracking origin mode:

• XRInputSubsystem.TrySetTrackingOriginMode sets the tracking origin mode
• XRInputSubystem.GetTrackingOriginMode retrieves the tracking origin mode
• XRInputSubsystem.GetSupportedTrackingOriginModes retrieves all tracking origin modes that the SDK supports

XR input through the legacy input system

You can still use the legacy input system, consisting of Input and XR.InputTracking, to retrieve XR input features. To do this, use the appropriate legacy input indices from the XR input mappings table on this page. In the Input section of the Player Settings (menu: Edit > Project Settings > Input), create an axis mapping to add the appropriate mapping from input name to axis index for the platform device’s feature. To retrieve the button or axis value, use Input.GetAxis or Input.GetButton and pass in the now-mapped axis or button name.

For more information about how to use the button and joystick axes, see documentation on the InputManager.

Haptics

You can send haptic events to an InputDevice. Haptics take on the form of an impulse, with an amplitude and duration.

Not all platforms support all types of haptics, but you can query a device for haptic capabilities. The following example gets an input device for the right hand, checks to see if the device is capable of haptics, and then plays back an impulse if it’s capable:

List<UnityEngine.XR.InputDevice> devices = new List<UnityEngine.XR.InputDevice>(); 

UnityEngine.XR.InputDevices.GetDevicesWithRole(UnityEngine.XR.InputDeviceRole.RightHanded, devices);

foreach (var device in devices)
{
    UnityEngine.XR.HapticCapabilities capabilities;
    if (device.TryGetHapticCapabilities(out capabilities))
    {
            if (capabilities.supportsImpulse)
            {
                uint channel = 0;
                float amplitude = 0.5f;
                float duration = 1.0f;
                device.SendHapticImpulse(channel, amplitude, duration);
            }
    }
}

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• Updated XR input mappings table and refreshed code samples in 2019.2
• New functionality and behaviour in 2019.1 NewIn20191,NewIn20192