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使用 Solidity、Web3 和 Vue.js 创建区块链游戏
source link: https://xie.infoq.cn/article/5705d51884aeaefac253016c6
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Solidity
对于 Solidity 的初学者，可以关注 buildspace 上的教程。
这里智能合约需要完成用户角色创建，铸造选择的角色，然后用它来对抗 BOSS。
打开一个终端并使用以下命令在项目文件夹中创建一个文件夹：
mkdir vue-game-dapp进入创建的项目文件夹：
cd vue-game-dapp运行以下命令来初始化项目信息：
npm init填写项目信息，并安装相关依赖：
npm install @openzeppelin/contracts --savenpm install hardhat chai @nomiclabs/hardhat-waffle @nomiclabs/hardhat-ethers ethers ethereum-waffle --save-dev
现在编写智能合约，在项目根目录下创建智能合约文件夹 contracts ：
mkdir contracts在 contracts 文件夹中创建一个新文件并将其命名为 EpicGame.sol，并在其中写入以下代码：
// SPDX-License-Identifier: MITpragma solidity >=0.4.22 <0.9.0;
这始终是智能合约文件中的第一行，用来指定 solidity 的版本。现在来编写代码制作完整的游戏智能合约 EpicGame ：
// SPDX-License-Identifier: MITpragma solidity >=0.4.22 <0.9.0;import "@openzeppelin/contracts/token/ERC721/ERC721.sol";import "@openzeppelin/contracts/utils/Counters.sol";import "@openzeppelin/contracts/utils/Strings.sol";import "./libraries/Base64.sol";import "hardhat/console.sol";contract EpicGame is ERC721 {struct CharacterAttributes {uint256 characterIndex;string name;string imageURI;uint256 hp;uint256 maxHp;uint256 attackDamage;}struct BigBoss {string name;string imageURI;uint256 hp;uint256 maxHp;uint256 attackDamage;}BigBoss public bigBoss;using Counters for Counters.Counter;Counters.Counter private _tokenIds;CharacterAttributes[] defaultCharacters;mapping(uint256 => CharacterAttributes) public nftHolderAttributes;mapping(address => uint256) public nftHolders;event CharacterNFTMinted(address sender,uint256 tokenId,uint256 characterIndex);event AttackComplete(uint256 newBossHp, uint256 newPlayerHp);constructor(string[] memory characterNames,string[] memory characterImageURIs,uint256[] memory characterHp,uint256[] memory characterAttackDmg,string memory bossName,string memory bossImageURI,uint256 bossHp,uint256 bossAttackDamage) ERC721("Heroes", "HERO") {for (uint256 i = 0; i < characterNames.length; i += 1) {defaultCharacters.push(CharacterAttributes({characterIndex: i,name: characterNames[i],imageURI: characterImageURIs[i],hp: characterHp[i],maxHp: characterHp[i],attackDamage: characterAttackDmg[i]}));CharacterAttributes memory c = defaultCharacters[i];console.log("Done initializing %s w/ HP %s, img %s",c.name,c.hp,c.imageURI);}bigBoss = BigBoss({name: bossName,imageURI: bossImageURI,hp: bossHp,maxHp: bossHp,attackDamage: bossAttackDamage});console.log("Done initializing boss %s w/ HP %s, img %s",bigBoss.name,bigBoss.hp,bigBoss.imageURI);_tokenIds.increment();}function mintCharacterNFT(uint256 _characterIndex) external {uint256 newItemId = _tokenIds.current();_safeMint(msg.sender, newItemId);nftHolderAttributes[newItemId] = CharacterAttributes({characterIndex: _characterIndex,name: defaultCharacters[_characterIndex].name,imageURI: defaultCharacters[_characterIndex].imageURI,hp: defaultCharacters[_characterIndex].hp,maxHp: defaultCharacters[_characterIndex].hp,attackDamage: defaultCharacters[_characterIndex].attackDamage});console.log("Minted NFT w/ tokenId %s and characterIndex %s",newItemId,_characterIndex);nftHolders[msg.sender] = newItemId;_tokenIds.increment();emit CharacterNFTMinted(msg.sender, newItemId, _characterIndex);}function attackBoss() public {uint256 nftTokenIdOfPlayer = nftHolders[msg.sender];CharacterAttributes storage player = nftHolderAttributes[nftTokenIdOfPlayer];console.log("\nPlayer w/ character %s about to attack. Has %s HP and %s AD",player.name,player.hp,player.attackDamage);console.log("Boss %s has %s HP and %s AD",bigBoss.name,bigBoss.hp,bigBoss.attackDamage);require(player.hp > 0, "Error: character must have HP to attack boss.");require(bigBoss.hp > 0, "Error: boss must have HP to attack boss.");if (bigBoss.hp < player.attackDamage) {bigBoss.hp = 0;} else {bigBoss.hp = bigBoss.hp - player.attackDamage;}if (player.hp < bigBoss.attackDamage) {player.hp = 0;} else {player.hp = player.hp - bigBoss.attackDamage;}console.log("Boss attacked player. New player hp: %s\n", player.hp);emit AttackComplete(bigBoss.hp, player.hp);}function checkIfUserHasNFT()publicviewreturns (CharacterAttributes memory){uint256 userNftTokenId = nftHolders[msg.sender];if (userNftTokenId > 0) {return nftHolderAttributes[userNftTokenId];} else {CharacterAttributes memory emptyStruct;return emptyStruct;}}function getAllDefaultCharacters()publicviewreturns (CharacterAttributes[] memory){return defaultCharacters;}function getBigBoss() public view returns (BigBoss memory) {return bigBoss;}function tokenURI(uint256 _tokenId)publicviewoverridereturns (string memory){CharacterAttributes memory charAttributes = nftHolderAttributes[_tokenId];string memory strHp = Strings.toString(charAttributes.hp);string memory strMaxHp = Strings.toString(charAttributes.maxHp);string memory strAttackDamage = Strings.toString(charAttributes.attackDamage);string memory json = Base64.encode(bytes(string(abi.encodePacked('{"name": "',charAttributes.name," -- NFT #: ",Strings.toString(_tokenId),'", "description": "This is an NFT that lets people play in the game", "image": "',charAttributes.imageURI,'", "attributes": [ { "trait_type": "Health Points", "value": ',strHp,', "max_value":',strMaxHp,'}, { "trait_type": "Attack Damage", "value": ',strAttackDamage,"} ]}"))));string memory output = string(abi.encodePacked("data:application/json;base64,", json));return output;}}
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