淺談 NFT
以及我ㄉ觀點
先打預防針
剛踏入鏈/幣圈 一個多月
約莫兩年經驗的軟體工程師
背景
如果有講錯請多多包涵,也歡迎大家分享交流
所以還是會穿插一些工程師視角
(因為也想知道工程端是怎麼實踐這些事)
拉回正題
先看定義
Non-Fungible Token(非質化代幣)
一種可以在鏈上交易的代幣格式,可夾帶著 metadata (ex: link, description)等資產相關資訊
並保有永久性、不可篡改性、真實性
而由於非質化的特性,幣與幣之間並不是等值的
阿如果連結的圖是放在第三方托管的話,
還是有可能被修改d
怎麼實現的? 基於 ERC 721
ERC 721 就是個開發 NFT 的協議
而 ERC 20 就是開發比特幣、以太幣那種同質化幣種
阿所謂的協議如果用工程師的視角來看的話,就是當你在開發時時需要引用協議的 abstract class,這個 class 裡面已經定義好部分的 method 供開發者使用
pragma solidity ^0.4.20;
/// @title ERC-721 Non-Fungible Token Standard
/// @dev See https://eips.ethereum.org/EIPS/eip-721
/// Note: the ERC-165 identifier for this interface is 0x80ac58cd.
interface ERC721 /* is ERC165 */ {
/// @dev This emits when ownership of any NFT changes by any mechanism.
/// This event emits when NFTs are created (`from` == 0) and destroyed
/// (`to` == 0). Exception: during contract creation, any number of NFTs
/// may be created and assigned without emitting Transfer. At the time of
/// any transfer, the approved address for that NFT (if any) is reset to none.
event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);
/// @dev This emits when the approved address for an NFT is changed or
/// reaffirmed. The zero address indicates there is no approved address.
/// When a Transfer event emits, this also indicates that the approved
/// address for that NFT (if any) is reset to none.
event Approval(address indexed _owner, address indexed _approved, uint256 indexed _tokenId);
/// @dev This emits when an operator is enabled or disabled for an owner.
/// The operator can manage all NFTs of the owner.
event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
/// @notice Count all NFTs assigned to an owner
/// @dev NFTs assigned to the zero address are considered invalid, and this
/// function throws for queries about the zero address.
/// @param _owner An address for whom to query the balance
/// @return The number of NFTs owned by `_owner`, possibly zero
function balanceOf(address _owner) external view returns (uint256);
/// @notice Find the owner of an NFT
/// @dev NFTs assigned to zero address are considered invalid, and queries
/// about them do throw.
/// @param _tokenId The identifier for an NFT
/// @return The address of the owner of the NFT
function ownerOf(uint256 _tokenId) external view returns (address);
/// @notice Transfers the ownership of an NFT from one address to another address
/// @dev Throws unless `msg.sender` is the current owner, an authorized
/// operator, or the approved address for this NFT. Throws if `_from` is
/// not the current owner. Throws if `_to` is the zero address. Throws if
/// `_tokenId` is not a valid NFT. When transfer is complete, this function
/// checks if `_to` is a smart contract (code size > 0). If so, it calls
/// `onERC721Received` on `_to` and throws if the return value is not
/// `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`.
/// @param _from The current owner of the NFT
/// @param _to The new owner
/// @param _tokenId The NFT to transfer
/// @param data Additional data with no specified format, sent in call to `_to`
function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
/// @notice Transfers the ownership of an NFT from one address to another address
/// @dev This works identically to the other function with an extra data parameter,
/// except this function just sets data to "".
/// @param _from The current owner of the NFT
/// @param _to The new owner
/// @param _tokenId The NFT to transfer
function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;
/// @notice Transfer ownership of an NFT -- THE CALLER IS RESPONSIBLE
/// TO CONFIRM THAT `_to` IS CAPABLE OF RECEIVING NFTS OR ELSE
/// THEY MAY BE PERMANENTLY LOST
/// @dev Throws unless `msg.sender` is the current owner, an authorized
/// operator, or the approved address for this NFT. Throws if `_from` is
/// not the current owner. Throws if `_to` is the zero address. Throws if
/// `_tokenId` is not a valid NFT.
/// @param _from The current owner of the NFT
/// @param _to The new owner
/// @param _tokenId The NFT to transfer
function transferFrom(address _from, address _to, uint256 _tokenId) external payable;
/// @notice Change or reaffirm the approved address for an NFT
/// @dev The zero address indicates there is no approved address.
/// Throws unless `msg.sender` is the current NFT owner, or an authorized
/// operator of the current owner.
/// @param _approved The new approved NFT controller
/// @param _tokenId The NFT to approve
function approve(address _approved, uint256 _tokenId) external payable;
/// @notice Enable or disable approval for a third party ("operator") to manage
/// all of `msg.sender`'s assets
/// @dev Emits the ApprovalForAll event. The contract MUST allow
/// multiple operators per owner.
/// @param _operator Address to add to the set of authorized operators
/// @param _approved True if the operator is approved, false to revoke approval
function setApprovalForAll(address _operator, bool _approved) external;
/// @notice Get the approved address for a single NFT
/// @dev Throws if `_tokenId` is not a valid NFT.
/// @param _tokenId The NFT to find the approved address for
/// @return The approved address for this NFT, or the zero address if there is none
function getApproved(uint256 _tokenId) external view returns (address);
/// @notice Query if an address is an authorized operator for another address
/// @param _owner The address that owns the NFTs
/// @param _operator The address that acts on behalf of the owner
/// @return True if `_operator` is an approved operator for `_owner`, false otherwise
function isApprovedForAll(address _owner, address _operator) external view returns (bool);
}
ERC 721 interface
//Contract based on https://docs.openzeppelin.com/contracts/3.x/erc721
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.3;
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
contract MyNFT is ERC721, Ownable {
using Counters for Counters.Counter;
Counters.Counter private _tokenIds;
constructor() public ERC721("MyNFT", "NFT") {}
function mintNFT(address recipient, string memory tokenURI)
public onlyOwner
returns (uint256)
{
_tokenIds.increment();
uint256 newItemId = _tokenIds.current();
_mint(recipient, newItemId);
_setTokenURI(newItemId, tokenURI);
return newItemId;
}
}
所以如果要做一個 NFT 大概會像這樣
Opensea
那如果單看協議,ERC 20 和 ERC 721 差在哪?
來看看 method 上面的定義
簡單來說 transferFrom 這個 method 被使用就會
ERC 20
from address: - x token
to address: + x token
ERC 721
釐清一些基本定義後,我們來看看
NFT 的價值
NFT 價值 = Intrinsic Value (內在價值)+ Utility Value (使用價值) + Premium (溢價)
目前的 NFT 類資產大多數的價值是來自於「溢價」,「內在價值」和「使用價值」相對比較低,甚至爲 0,換句話說就是沒什麼基本面
NFT project 只是科技菁英們的多層式傳銷
透過創造社群共同認同感
以及拉新下線來不斷炒高 NFT 價格
2021/12/16
這樣有不好嗎?其實也未必
價值確實本來就是由社群共識擬定的
(ex 線上遊戲虛寶)
但我只想知道有沒有感覺更實際的應用?
但在此之前我們還是先來看看目前有哪些應用
複習一下有哪些 NFT project
NFT Project
以及小故事
Collection
Social Proof
cyrpto punk
cyrpto phunk
購買NFT數位藝術品,
不代表你擁有作品的「所有權」和「著作權」
實驗
跟大多數的實驗藝術一樣,敬佩但我跟不上
Game/Metaverse
Membership
透過 NFT 入會,進而得到高價值資訊
https://www.ptt.cc/bbs/DigiCurrency/M.1639202802.A.7D0.html
例如一開始就限定發行數量、盲盒、burn、 nft 碎片化
應用除了前面所提到,這交易的過程也有很多玩法,
這些玩法可能是為了趣味性、減少手續費、想辦法增加稀缺性等等
盲盒(blind box)
盲盒(blind box)
abstract contract BaseERC721BlindBox is BaseERC721 {
using Strings for uint256;
bool private _blindBoxOpened = false;
string private _blindTokenURI =
"ipfs://QmexqcLDvoP6HCTtSGumG3yzhZdH8guvV3z3kReCvf2QKn";
function _isBlindBoxOpened() internal view returns (bool) {
return _blindBoxOpened;
}
function setBlindBoxOpened(bool _status) public {
require(
hasRole(DEFAULT_ADMIN_ROLE, _msgSender()),
"BaseERC721BlindBox: only admin can do this action"
);
_blindBoxOpened = _status;
}
// this function controls how the token URI is constructed
function tokenURI(uint256 tokenId)
public
view
virtual
override
returns (string memory)
{
require(
_exists(tokenId),
"ERC721Metadata: URI query for nonexistent token"
);
if (_blindBoxOpened) {
string memory baseURI = _baseURI();
return
bytes(baseURI).length > 0
? string(
abi.encodePacked(baseURI, tokenId.toString(), ".json")
)
: "";
} else {
return _blindTokenURI;
}
}
}
還有 ntf 借貸等等之後再提
目前乍看之下,大部分的應用都還很虛
就是爛
但我自己覺的 NFT 還是很有價值的技術手段,只是當前的載體/應用還不盡成熟
NFT 本身的價值個人認為有二
1. 不可偽證性(資產上鏈)
2. 原創者可抽取版稅
上鏈後雖然還是要透過第三方的機構取作認證,但至少可以確保來源、交易對象等資訊不會被篡改
數位資產
將合約、權杖等重要資訊進行數位資產化,傳統作法無法輕易的保障資料來源的可靠性
任何會員或訂票系統
(演唱會、訂房、球賽)
- 不可偽證性很好作為會員/門票的憑證
- 也可以利用制定智能條約,禁止其在二級市場做交易,或是抽取版稅
(前提是錢包與會員等綁定也要先做好)
但這種 to C 端的服務會遇到什麼困難?
上手不易(創錢包,出入金,選鏈......
解決之道有兩種
教育市場,降低門檻
教育市場
降低門檻
錢包降低上手門檻
(qubic, blocto......etc)
就如前面提到的,因為這些新知識所造成的門檻
目前市場上大部分項目還是幣圈人在自爽
NFT 只是技術手段,不是目的,否則就是本末倒置,爲了 NFT 而 NFT 毫無意義。
就醬 感謝大家
REF
淺談 NFT
By Jay Chou
淺談 NFT
- 461