Using the Liminal SDK - LiminalVR/DeveloperWiki GitHub Wiki

The QuickStart for SDK Integration guides you through the process of importing the Liminal SDK and setting up your project.

• During scene setup a new object named 'ExperienceApp' is created at the root of the scene. This becomes the parent of any existing GameObjects within the scene.
• If you create any new GameObjects after this process, they should also be parented under the 'ExperienceApp' root object.

When running within the Liminal App, an Experience begins with loading the scene from the .limapp package. This process is similar to loading a Unity Scene. However the initialization sequence has some key differences.

1. Awake() will be called in sequence on any active GameObjects. At this point the GameObjects have not yet been deserialized and other GameObjects may not yet be active. Your Awake() methods should not depend on serialized data or on other objects being active in the scene (e.g. FindObjectOfType()).
2. GameObjects are then disabled with a SetActive(false) call
3. [Serializable] classes are now deserialized
4. GameObjects are re-enabled with a SetActive(true) call
5. The ExperienceApp.Initializing event is fired

ExperienceApp.Initializing is raised after the ExperienceApp finishes initializing.

Important: If your Awake() function relies on an object being alive in the scene such as FindObjectOfType(), then you may experience null reference issues when the Experience begins.

Solution : Perform any initialization that depends on serialized data or on other GameObjects in a listener to ExperienceApp.Initializing. The event can be subscribed to from Awake():

using Liminal.SDK.Core;
using UnityEngine;

public class ExampleScript : MonoBehaviour
{
    private void Awake()
    {
        ExperienceApp.Initializing += Init;
    }

    private void Init()
    {
        //Initialize my class
    }
}

The SDK comes with Demo Scenes which can be located in your project under Liminal/Examples/. Each of the scenes showcase different features of the SDK.

The Liminal.SDK.VR.VRDevice class allows developers to track input from VR devices in a similar way to Unity's Input class. To monitor the active input device e.g. for button presses, use VRDevice.Device.PrimaryInputDevice.

using Liminal.SDK.VR;
using Liminal.SDK.VR.Input;
using UnityEngine;

public class VRInputExample : MonoBehaviour
{
    private void Update()
    {
        //Get the primaryInput
        var primaryInput = VRDevice.Device.PrimaryInputDevice;

        if (primaryInput.GetButtonUp(VRButton.One))
        {
            //Trigger has been pressed and released
        }
    }
}

The Liminal SDK uses a custom input module that allows users to interact with Unity UI elements the same way the mouse does. If it is not working, please ensure that the EventSystem has a VRPointerInputModule component.

Pointers use the VRPhysicsRaycaster component (found in the scene under VRAvatar > Auxiliaries). This allows 3D objects to become interactive in the same way as Unity UI elements by implementing the IPointerClickHandler interface.

Important: The object must have a 3D collider such as MeshCollider or BoxCollider.

using UnityEngine;
using UnityEngine.EventSystems;

public class CubePointerUpExample : MonoBehaviour, IPointerClickHandler
{
    public void OnPointerClick(PointerEventData eventData)
    {
        Debug.Log("The object has been clicked");
    }
}

The GazeInput component of the VRAvatar GameObject allows VR devices without a controller to interact with Unity UI & 3D objects via gaze. You can set the Hover Duration field of this component to control how long gaze remains on an object before an event is dispatched.

The GazeInput.ActivationPolicy field defines when gaze input is used. Setting to Never disabled gaze input completely, even if no other controller is in use.

1. Locate the controller from VRAvatar > PrimaryHand > Anchor > Controller
2. Remove the controller
3. Add your own model on the Anchor object

Important: If you do not wish a controller to be visible in your Experience, remove VRAvatar > PrimaryHand > Anchor > Controller

This process will generate a .limapp file of your scene.

Important: Open the console log before building your Experience. The build process can take a while, so be patient. Once complete, the log will display that the limapp build process was successful.

From the Liminal Build Window:

1. Select the platform
2. Click Build.

Important If you not on the Platform you selected, all assets will have to be imported again to the platform, so this process will take a long time. It is advised to build for your current platform.