NFT是独一无二的,但它却不是一成不变的。所以NFT是可以成长的,可以通过两个不同的NFT合成一个新的NFT。生成的一个新的NFT,有的自己属性和技能同样继承NFT的属性让NFT实现更多玩法。
ProTradex目前基于NFT的去中心化杠杆抵押借贷协议，区别于目前市面上的NFT借贷平台，不仅仅允许用户将NFT资源抵押到资金池中，获得U等加密资源，也支持用户将加密资源在协议中抵押。
项目中，我们初次mint出来的NFT等级是0级，并且它们的创建者也是0，通过两个NFT合成之后创建一个新的NFT,新的NFT等级会+1，并且会继承原NFT的的Id。
代码实战
//SPDX-License-Identifier:MIT
pragma solidity^0.8.9;
import"openzeppelin/contracts/token/ERC721/ERC721.sol";
import"openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import"openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import"openzeppelin/contracts/utils/Counters.sol";
import"openzeppelin/contracts/utils/Strings.sol";
import"hardhat/console.sol";
contract ComposeNFT is ERC721,ERC721Enumerable,ERC721URIStorage{
using Counters for Counters.Counter;
using Strings for uint256;
Counters.Counter private _tokenIdCounter;
struct Donkey{
address owner;
uint tokenId;
uint8 level;
uint dadId;//父
uint mumId;//母
string uri;
}
Donkey[]public donkeys;
constructor()ERC721("Donkeys NFT","DONKEYS"){
}
function _baseURI()internal pure override returns(string memory){
return"https://raw.githubusercontent.com/qdwds/NFT-metadata/master/metadata/donkeys/";
}
function _setURI(uint256 _level)internal view returns(string memory uri){
uint random=_random(100)+1;
uri=string(abi.encodePacked(_level.toString(),"/images/",random.toString(),".png"));
}
function _random(uint _max)internal view returns(uint256){
uint256 random=uint256(keccak256(abi.encodePacked(msg.sender,block.timestamp,block.coinbase,gasleft())));
return(random>block.number)?(random-block.number)%_max:(block.number-random)%_max;
}
function safeMint(address _to)public{
_innerMint(_to,0,0,0);
}
function batchSafeMint(address _to,uint8 _numWords)public{
require(_numWords<=100,"MAX mint 10");
for(uint i=0;i<_numWords;i++){
_innerMint(_to,0,0,0);
}
}
function _innerMint(address _to,uint8 _level,uint256 _dadId,uint256 _mumId)internal{
uint256 tokenId=_tokenIdCounter.current();
_tokenIdCounter.increment();
string memory uri=string(abi.encodePacked(_baseURI(),_setURI(_level)));
Donkey memory donkey=Donkey({
owner:_to,
tokenId:tokenId,
level:_level,
mumId:_mumId,
dadId:_dadId,
uri:uri
});
donkeys.push(donkey);
_safeMint(_to,tokenId);
_setTokenURI(tokenId,uri);
}
function getDonkey(uint256 _tokenId)public view returns(Donkey memory donkey){
donkey=donkeys[_tokenId];
}
function getDonkeys(address _owner)public view returns(Donkey[]memory ownerDonkeys){
uint balance=balanceOf(_owner);
ownerDonkeys=new Donkey[](balance);
for(uint256 i=0;i<balance;i++){
uint index=tokenOfOwnerByIndex(_owner,i);
ownerDonkeys<i>=donkeys[index];
}
}
function breed(uint256 _dadId,uint256 _mumId)public{
Donkey memory dad=donkeys[_dadId];
Donkey memory mum=donkeys[_mumId];
require(dad.owner==msg.sender&&mum.owner==msg.sender,"Pass?");
require(dad.level==mum.level,"level fild");
require(dad.level<3,"Create MAX level 3");
_innerMint(msg.sender,dad.level+1,dad.tokenId,mum.tokenId);
}
//The following functions are overrides required by Solidity.
function _beforeTokenTransfer(address from,address to,uint256 tokenId,uint256 batchSize)
internal
override(ERC721,ERC721Enumerable)
{
super._beforeTokenTransfer(from,to,tokenId,batchSize);
}
function _burn(uint256 tokenId)internal override(ERC721,ERC721URIStorage){
super._burn(tokenId);
}
function tokenURI(uint256 tokenId)
public
view
override(ERC721,ERC721URIStorage)
returns(string memory)
{
return super.tokenURI(tokenId);
}
function supportsInterface(bytes4 interfaceId)
public
view
override(ERC721,ERC721Enumerable)
returns(bool)
{
return super.supportsInterface(interfaceId);
}
}
