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2D Game Example

Overview

This section showcases the Cronos play Gaming SDK integration with the Cronos chain, aiming to bring Unity games into the Cronos ecosystem. In particular, we will show how to do a basic integration of the Cronos play with the Cronos chain including:

  • Connecting to Cronos networks;

  • Installaiton of the SDK;

  • Obtaining a sample NFT and;

  • Import Sample package from Unity Asset Store

Pre-requisites

  1. Unity (Version 2020.3.25f1 or later)

  2. ChainSafe SDK

  3. Metamask browser extension

Network Name: Cronos Mainnet Beta

  • New RPC URL: https://evm-dev.cronos.org/

  • Chain ID: 25

  • Currency Symbol: CRO

  • Block Explorer URL: https://explorer.cronos.org/

Integration guide for Cronos

Create a new project

  • Download the tutorial bolt kit from Unity and import the assets into the blank new project. Below are the steps for importing Tutorial Projects - Bolt Kit from Unity. See Reference #1.

Download the latest ChainSafe SDK and import it into the project.

Prefabs interaction

  • Step 3a. [Unity] Double click the Level1 scene under Assets/Scenes directory

Transfer721 Example

  • Drag the Transfer721 prefab under Assets/Web3Unity/Prefabs/WebGL dir into the scene.

  • Update the Contract address under Transfer721Script object inspector

  • Update the To Account address to your desired wallet address

* For acquiring the NFT, you can create your own (see Reference #2), or mint an ERC721 NFT at our Cronos NFT faucet (see Reference #3).

Build and Run

  1. Switch to WebGL platform

  1. Click the Player Setting button

  2. Select Web3GL-2020 under Resolution and Presentation tab

  1. Set Compression Format to Disabled under Publishing Settings tab

  1. After that, click Build and Run button and you are ready to play.

What's next

The above guideline documentation only highlights the basic integration between ChainSafe and Cronos chain. You can download the full source code of the above sample game here. For other ERC protocol methods, please refer to the ChainSafe Documentation.

Reference

Import Sample package from Unity Asset Store

1a. Click to add the asset and sign in to your Unity account

1b. Create a new project in Unity

1c. Open the Package Manager window in Unity and under "My Assets" download the Bolt Kit.

1d. Select Bolt Kit: Platformer Tutorial Assets and click Import

Smart contract

2a. Create an ERC standard smart contract

  • ERC20 example

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;

import "@openzeppelin/[email protected]/token/ERC20/ERC20.sol";
import "@openzeppelin/[email protected]/access/Ownable.sol";

contract MyToken is ERC20, Ownable {
    constructor() ERC20("MyToken", "MTK") {
        _mint(msg.sender, 1000 * 10 ** decimals());
    }

    function mint(address to, uint256 amount) public onlyOwner {
        _mint(to, amount);
    }
}

  • ERC721 example

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;

import "@openzeppelin/[email protected]/token/ERC721/ERC721.sol";
import "@openzeppelin/[email protected]/access/Ownable.sol";
import "@openzeppelin/[email protected]/utils/Counters.sol";

contract MyNFT is ERC721, Ownable {
    using Counters for Counters.Counter;

    Counters.Counter private _tokenIdCounter;

    constructor() ERC721("MyNFT", "MNFT") {}

    function _baseURI() internal pure override returns (string memory) {
        return "https://opensea-creatures-api.herokuapp.com/api/creature/";
    }

    function safeMint(address to) external onlyOwner {
        uint256 tokenId = _tokenIdCounter.current();
        _tokenIdCounter.increment();
        _safeMint(to, tokenId);
    }
}

  • ERC1155 example

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;

import "@openzeppelin/[email protected]/token/ERC1155/ERC1155.sol";
import "@openzeppelin/[email protected]/access/Ownable.sol";

contract My1155Token is ERC1155, Ownable {
    constructor()
        ERC1155("https://opensea-creatures-api.herokuapp.com/api/creature/")
    {}

    function setURI(string memory newuri) public onlyOwner {
        _setURI(newuri);
    }

    function mint(address account, uint256 id, uint256 amount, bytes memory data)
        public
        onlyOwner
    {
        _mint(account, id, amount, data);
    }

    function mintBatch(address to, uint256[] memory ids, uint256[] memory amounts, bytes memory data)
        public
        onlyOwner
    {
        _mintBatch(to, ids, amounts, data);
    }
}

2b. Deploy Smart Contract via Remix IDE

-  Switch the chain network to Cronos Testnet via Metamask extension or other similar provider
-  Select the `Injected Web3` under ENVIRONMENT tab
-  Approve the connection
-  Select your contract name under CONTRACT tab
-  Approve the transaction after clicking `Deploy` button
-  Copy the contract address

NFT Faucet

  • 1. Connect your wallet via metamask or walletconnect

  • 2. Click Create NFT under YOUR COLLECTION tab

  • 3. Create and sign the transaction after uploading the image

  • 4. Copy the contract address and image URL from the NFT modal

  • 5. Paste into the corresponding input box inside Unity inspector

(Optional) List NFT for sale in marketplace faucet

  • 1. Fill in the price at list item modal and confirm

  • 2. Sign approval and create item transaction

  • 3. View the listed item in Marketplace tab

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