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NFT

Github Link: https://github.com/eatthepie/contracts-layer2/blob/main/src/NFTPrize.sol

The NFT contract implements an ERC721 contract to mint NFTs for jackpot winners. Each NFT features dynamically generated SVG artwork displaying the winning numbers in a unique quadrant-based design.

Key Features​

  • 🎨 Dynamic SVG generation
  • 🔢 Custom number rendering system

Contract Structure​

Inheritance​

  • ERC721: OpenZeppelin's ERC721 implementation

Dependencies​

  • @openzeppelin/contracts/token/ERC721/ERC721.sol
  • @openzeppelin/contracts/utils/Base64.sol
  • @openzeppelin/contracts/utils/Strings.sol

Key Data Structures​

struct NumberSVG {
    bytes path;
    uint256 width;
}
  • path: SVG path data for rendering a number
  • width: Width of the number's SVG representation

State Variables​

mapping(uint256 => NumberSVG) private numberSVGs;
address public lotteryContract;
bool private initialized;
mapping(uint256 => uint256) private tokenGameNumbers;
mapping(uint256 => uint256[4]) private tokenWinningNumbers;
mapping(uint256 => uint256) private tokenPayouts;

Core Functionality​

Initialization​

function setLotteryContract(address _lotteryContract) external
  • Sets the authorized lottery contract address
  • Can only be called once
  • Required before minting can begin

NFT Minting​

function mintNFT(
    address winner,
    uint256 tokenId,
    uint256 gameNumber,
    uint256[4] calldata winningNumbers,
    uint256 payout
) external
  • Only callable by lottery contract
  • Mints NFT to winner's address
  • Stores game details and winning numbers
  • Records payout amount

Metadata Generation​

function tokenURI(uint256 tokenId) public view returns (string memory)
  • Returns base64-encoded JSON metadata
  • Includes:
    • Name with game number
    • Description
    • Dynamic SVG image
    • Game attributes
    • Winning numbers
    • Payout amount