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pragma solidity 0.8.0; | |
// We need some util functions for strings. | |
import "@openzeppelin/contracts/utils/Strings.sol"; | |
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol"; | |
import "@openzeppelin/contracts/utils/Counters.sol"; | |
import "hardhat/console.sol"; | |
contract MyEpicNFT is ERC721URIStorage { | |
using Counters for Counters.Counter; | |
Counters.Counter private _tokenIds; | |
// This is our SVG code. All we need to change is the word that's displayed. Everything else stays the same. | |
// So, we make a baseSvg variable here that all our NFTs can use. | |
string baseSvg = "<svg xmlns='http://www.w3.org/2000/svg' preserveAspectRatio='xMinYMin meet' viewBox='0 0 350 350'><style>.base { fill: white; font-family: serif; font-size: 24px; }</style><rect width='100%' height='100%' fill='black' /><text x='50%' y='50%' class='base' dominant-baseline='middle' text-anchor='middle'>"; | |
// I create three arrays, each with their own theme of random words. | |
// Pick some random funny words, names of anime characters, foods you like, whatever! | |
string[] firstWords = ["YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD"]; | |
string[] secondWords = ["YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD"]; | |
string[] thirdWords = ["YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD", "YOUR_WORD"]; | |
constructor() ERC721 ("SquareNFT", "SQUARE") { | |
console.log("This is my NFT contract. Woah!"); | |
} | |
// I create a function to randomly pick a word from each array. | |
function pickRandomFirstWord(uint256 tokenId) public view returns (string memory) { | |
// I seed the random generator. More on this in the lesson. | |
uint256 rand = random(string(abi.encodePacked("FIRST_WORD", Strings.toString(tokenId)))); | |
// Squash the # between 0 and the length of the array to avoid going out of bounds. | |
rand = rand % firstWords.length - 1; | |
return firstWords[rand]; | |
} | |
function pickRandomSecondWord(uint256 tokenId) public view returns (string memory) { | |
uint256 rand = random(string(abi.encodePacked("SECOND_WORD", Strings.toString(tokenId)))); | |
rand = rand % secondWords.length - 1; | |
return secondWords[rand]; | |
} | |
function pickRandomThirdWord(uint256 tokenId) public view returns (string memory) { | |
uint256 rand = random(string(abi.encodePacked("THIRD_WORD", Strings.toString(tokenId)))); | |
rand = rand % thirdWords.length - 1; | |
return thirdWords[rand]; | |
} | |
function random(string memory input) internal pure returns (uint256) { | |
return uint256(keccak256(abi.encodePacked(input))); | |
} | |
function makeAnEpicNFT() public { | |
uint256 newItemId = _tokenIds.current(); | |
// We go and randomly grab one word from each of the three arrays. | |
string memory first = pickRandomFirstWord(newItemId); | |
string memory second = pickRandomSecondWord(newItemId); | |
string memory third = pickRandomThirdWord(newItemId); | |
// I concatenate it all together, and then close the <text> and <svg> tags. | |
string memory finalSvg = string(abi.encodePacked(baseSvg, first, second, third, "</text></svg>")); | |
console.log("\n--------------------"); | |
console.log(finalSvg); | |
console.log("--------------------\n"); | |
_safeMint(msg.sender, newItemId); | |
// We'll be setting the tokenURI later! | |
_setTokenURI(newItemId, "blah"); | |
_tokenIds.increment(); | |
console.log("An NFT w/ ID %s has been minted to %s", newItemId, msg.sender); | |
} | |
} |
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