ZEBEDEE Unity SDK

The ZEBEDEE Unity SDK allows developers to easily integrate Bitcoin Lightning microtransactions into their games and digital experiences. The SDK aims to provide helper methods to improve upon developer experience. The following backend systems are available for the Unity SDK:

1. ZEBEDEE Lightning API
2. BTCPay Server API
3. LND API

ZEBEDEE Lightning API

General Information

The current ZEBEDEE API exposes 3 major entities and endpoints:

ZEBEDEE API	Use Case
Charge	Shows QR code with Invoice (BOLT 11) that Player can pay for in satoshis.
Withdraw	Shows QR code with LNURL Invoice that allows Player to Withdraw satoshis.
Payment	Scans the Invoice (BOLT11) QR code from Player’s wallet and pays satoshis.

The SDK exposes a set of helper methods, including a client constructor that facilitates the interaction with the ZEBEDEE APIs.

API Client Constructor

ZEBEDEE Client is the only object with which Unity C# code interacts with. The constructor requires a zebedeeBaseURL and a apikey. You can get those and more documentation at the ZEBEDEE website. Developers can get an API Key from the Developer Dashboard -> Games -> Create a New Game. API calls without an API Key will fail.

    public string zebedeeBaseUrl;   //set host from inspector
    public string apiKey;           //set pairing code from inspector
    
    private ZebedeeClient zbdClient = null;

    public void Start()
    {
        zbdClient = new ZebedeeClient(zebedeeBaseUrl, apiKey);
    }

Developers can also pass these settings via the Public Properties of Unity Game object. See below for reference.

CreateInvoice Method

The CreateIvoice method is used to generate BOLT11 Invoices. The method expects an amount and a description. It is commonplace to showcase the Invoice in a QR code format, for users and players to scan. As soon as the Invoice is generated in the ZEBEDEE backend services, the callback method is executed with the corresponding BOLT11 Invoice string returned (e.g. lnbc125bj1...).

// New Invoice Preparation
InvoiceRequest invoiceReq = new InvoiceRequest();

invoiceReq.MilliSatoshiAmount = int.Parse(amount.text) * 1000;
invoiceReq.Description = product.text;

// Create Invoice with data and receive Invoice BOLT11 string
await zbdClient.CreateInvoice(invoiceReq, handleInvoice);

Withdraw Method

ZEBEDEE WithdrawAsync method is used to generate LNURL strings for withdrawing funds. The method expects an amount and a description. Developers are encouraged to show these as QR codes so players and users can scan them. As soon as the Withdrawal Request LNURL is generated the callback method is executed with the LNURL string returned.

// Withdrawal Request Preparation
WithdrawRequest withdrawReq = new WithdrawRequest();

withdrawReq.Amount = int.Parse(amount.text);
withdrawReq.Description = product.text;
withdrawReq.InternalId = product.text;

// Create Invoice with data and receive LNURL string
await zbdClient.WithDrawAsync(withdrawReq, handleWithdrawal);```

SubscribeToInvoice Method

In order to get information about the status of a recently created Invoice, one can use the SubscribeToInvoice method. This allows developers to respond to any updates on the status of a payment inside of their applications and games. For example, showing Paid Invoice image.

SubscribeToWithdraw Method

In order to get information about the status of a recently created Withdrawal Request, one can use the SubscribeToWithdraw method. This allows developers to respond to any updates on the status of a withdrawal inside of their applications and games. For example, showing Withdrawal Complete image.

Payment Method

In case the Player’s wallet does not support LNURL QR codes, you may pay an invoice directly. Game developers can possibly implement an input for user to paste an invoice, or even a webcam feature to scan the Invoice QR code on the Player’s phone.

Examples / Demo Implementation

This repository also contains a Sample Unity project under /<Project Folder>/Unity/ZebedeeUnity/. To run the project, follow the steps below:

1. Open this folder with the latest Unity software.
2. Open the ZEBEDEE scene.
3. Set the ZEBEDEE URL and your API Key (found in ZEBEDEE’s Developer Dashboard) on the Game Object ZebedeeClient
4. Start the game.
5. Test Player paying to the Game (Genarating BOLT Invoice)
   1. Input Description and Amount in satoshis
   2. Click “Pay for Game Item”
   3. Open you lightning wallet and SCan the QR code
   4. QR image turns in to Paid Image
6. Test Player withdrawing from the Game (Generating LNURL withdraw)
   1. Input Description and Amount in satoshis
   2. Click “Withdraw my Sats”
   3. Open you LNURL-supported lightning wallet and scan
   4. QR image turns in to Withdraw Complete Image

Acknowledgement

This SDK depends on several opensource projects below.

Project	License	URL
Bitpay Csharp client	MIT	https://github.com/bitpay/csharp-bitpay-client#license
NBitcoin	MIT	https://github.com/MetacoSA/NBitcoin/blob/master/LICENSE
BouncyCastle.Crypto	MIT	http://www.bouncycastle.org/csharp/licence.html
log4net	Apache 2.0	https://logging.apache.org/log4net/license.html
Multibase	MIT	https://logging.apache.org/log4net/license.html
NewtonJson	MIT	https://github.com/JamesNK/Newtonsoft.Json/blob/master/LICENSE.md