Adding an entity​

Manna module makes it easy to join a session and get instantly calibrated into a shared coordinate system by scanning a Lighthouse (a QR code in this case). Follow these steps to install and use Manna:

1. Open the Package Manager and install the ^Manna^ module.

start-note

If you are experiencing issues with Unity editor when installing a new package, try restarting Unity.

end-note

2. Import ^Manna^

using Auki.ConjureKit.Manna;

3. Create a private ^Manna^ variable and initialize it right after ConjureKit

private Manna _manna;

private Manna _manna;

4. Declare a ^Button^ variable that will enable and disable the QR code and a ^bool^ variable to save the QR code visibility state.

[SerializeField] bool qrCodeBool;
[SerializeField] Button qrCodeButton;

5. Toggle the QR code button interactable state in ^ToggleControlsState^ method.

private void ToggleControlsState(bool interactable)
{
    if (spawnButton) spawnButton.interactable = interactable;
    if (qrCodeButton) qrCodeButton.interactable = interactable;
}

6. Add a ^ToggleLighthouse^ method and use _manna.SetLighthouseVisible(true) to show and hide the Lighthouse (QR code).

public void ToggleLighthouse()
{
    qrCodeBool = !qrCodeBool;
    _manna.SetLighthouseVisible(qrCodeBool);
}

7. Feed Manna with AR camera video frames acquired from ARCameraManager to recognize QR codes

start-note

Manna is independent of any specific AR SDK, like ARFoundation. You need to manually choose how to Feed Manna With Video Frames. An example of how to do it in conjunction with ARFoundation can be found in below and in the Manna demo sample.

end-note

private void Update()
{
    FeedMannaWithVideoFrames();
}

private void FeedMannaWithVideoFrames()
{
    var imageAcquired = arCameraManager.TryAcquireLatestCpuImage(out var cpuImage);
    if (!imageAcquired)
    {
        AukiDebug.LogInfo("Couldn't acquire CPU image");
        return;
    }

    if (_videoTexture == null) _videoTexture = new Texture2D(cpuImage.width, cpuImage.height, TextureFormat.R8, false);

    var conversionParams = new XRCpuImage.ConversionParams(cpuImage, TextureFormat.R8);
    cpuImage.ConvertAsync(
        conversionParams,
        (status, @params, buffer) =>
        {
            _videoTexture.SetPixelData(buffer, 0, 0);
            _videoTexture.Apply();
            cpuImage.Dispose();

            _manna.ProcessVideoFrameTexture(
                _videoTexture,
                arCamera.projectionMatrix,
                arCamera.worldToCameraMatrix
            );
        }
    );
}

8. Add a ^Button^ to the scene, configure the on click callback to invoke ^ToggleLighthouse^ method. Drag the button game object to the field you declared in step 5.

9. Subscribe to ^OnEntityAdded^ event to create cubes when other participants add entities in the session.

_conjureKit.OnEntityAdded += CreateCube;

Build to XCode

In File -> Build settings, make sure that you have added open scenes before building to Xcode.

Another Device B running the same app as Device A can now join Device A's Session by scanning the Lighthouse (QR code) of Device A.