godot-loopring-sdk

A simple SDK to integrate Loopring into Godot web games.

Note: This project is still a work-in-progress.

To-Do's:

• resolve_ens is untested
• Mobile is untested
• WalletConnect QR code login/signing

Features

• User login/logout through a Loopring compatible wallet.
• Fetch the user's NFT balance.

API Calls

These API calls are currently supported. See TestMainScene.tscn for an example scene of how to use them. More can be added to the Loopring.gd script.

Function	Use
get_api_key	Gets the user's L2 API Key
get_account_object	Gets the user's account information
get_token_balance	Gets the user's NFT data
resolve_ens	Gets Loopring ENS
get_metadata	Gets metadata from IPFS

Getting Started

Download the C# Mono version of Godot 3.5.2. Then either clone this repository and import the project, or just copy the addons/godot-loopring-sdk directory into your own project's addons directory and enable the SDK from Godot's plugins menu.

If you're copying the SDK over, make sure that your .csproj file has the following elements in <PropertyGroup> and <ItemGroup>:

<PropertyGroup>
  <TargetFramework>net472</TargetFramework>
  <LangVersion>latest</LangVersion>
  <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
</PropertyGroup>

<ItemGroup>
  <PackageReference Include="PoseidonSharp" Version="1.0.0" />
</ItemGroup>

Wallet Login/Logout

See TestLogin.tscn for an example login scene.

To connect to a user's wallet, add a Node with the WalletConnector.gd script attached to it. Then you can call WalletConnector's connect_to_web3_wallet() function and LoopringGlobals.set_wallet_type() with the wallet type the user picks. In the example login scene, there are 3 buttons for Metamask, GameStop, and WalletConnect. The wallet type needs to be passed into the above functions for the right connection process to happen.

When a wallet connection succeeds or fails, WalletConnector.gd emits a wallet_connected signal with the wallet string as its parameter. An empty string means the connection failed somehow, in which case you'll want to clear all global wallet data with LoopringGlobals.clear_wallet(). If the connection was successful, you can save the user's wallet and wallet type by writing to a ConfigFile, which lets you keep the user logged in. In the example login scene, we check if there's a user config file saved on ready, and we skip the login screen if a wallet is found.

You can log out the user by calling Loopring.logout(), which deletes all data from the config file located at LoopringGlobals.USER_DATA_SAVE_PATH and from the LoopringGlobals singleton itself.

Using the Loopring API

See TestMainScene.tscn for an example on how to use the Loopring API. Note that this scene also has its own node with WalletConnector.gd attached to it.

To query for the user's NFTs, we need a L2 API key. We can get the user's API key by querying for some data that eventually gets converted and passed into Loopring.get_api_key(). This entire process can be seen MainSceneManager.gd's functions get_account(), sign_message_function(), and get_api_key().

API key retrieval process (How it works)

First, we get the user's account data with Loopring.get_account_object(). Then we pass some of that data into the sign_web3_message() function from WalletConnector.gd to get an ECDSA signature, convert this signature into an EDDSA signature with the GetApiKeyEDDSASig() function from PoseidonHelper.cs, and then pass this signature into Loopring.get_api_key().

If the signing process fails in WalletConnector, a failed_to_sign signal will be emitted.

Once you have an API key, you can query for the user's NFTs with Loopring.get_token_balance(), which requires a user wallet, API key, the smart contract address for the NFTs to check, and a boolean for if metadata should be fetched. This query gives you a response that contains an array of objects with several fields. The metadata field will appear if the _get_metadata parameter is true. See the function get_tokens() in MainSceneManager.gd for an example of this entire process and how to read the metadata.

Notes

• Once Godot 4.0 is out, the SDK will need to be updated due to changes to coroutines and the replacement of yield with await. In the meantime, any calls to methods that wait for responses require checking if the return value is a GDScriptFunctionState, and if so, yield until completed.
• Godot 4.0's web exporting for C# is not working, so upgrading the SDK to 4.x will have to wait until those issues are fixed.

Credits

Loopmon - This SDK is based on Loopmon's Unity package (https://github.com/LoopMonsters/LoopringUnity)

Fudgey - PoseidonSharp

MetaBoy team - For advice and guidance on how to use the Loopring API and wallet connections.