发币模式

IEO

发行在中心化交易所，上币流程麻烦，中心化。

IDO

发行在去中心交易所，上币需要流动性成本高，面临价格和gas飙升、机器人/巨鲸等问题、发行效率低不利于价格发现。

LBP(Liquidity bootstrapping pool)

自定义流动性池的比例 balancer，属于荷兰拍的变种。

荷兰拍是什么

是一种特殊的拍卖形式，也称为“减价拍卖”，在荷兰拍卖中，拍卖标的的竞价由高到低依次递减直到第一个竞买人应价。 荷兰式拍卖有两个显著特点。

• 一，价格随着一定的时间间隔，按照事先确定的降价阶梯，由高到低递减。

• 二，所有买受人(即买到物品的人)都**以最后的竞价(即所有买受人中的最低出价)成交。**NFT荷兰拍的实现

NFT荷兰拍的实现

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "./ERC721A.sol";
import "@openzeppelin/contracts/utils/Strings.sol";

contract Azuki is Ownable, ERC721A, ReentrancyGuard {
  uint256 public immutable maxPerAddressDuringMint;
  uint256 public immutable amountForDevs;
  uint256 public immutable amountForAuctionAndDev;

  struct SaleConfig {
    uint32 auctionSaleStartTime;
    uint32 publicSaleStartTime;
    uint64 mintlistPrice;
    uint64 publicPrice;
    uint32 publicSaleKey;
  }

  SaleConfig public saleConfig;

  mapping(address => uint256) public allowlist;

  constructor(
    uint256 maxBatchSize_,
    uint256 collectionSize_,
    uint256 amountForAuctionAndDev_,
    uint256 amountForDevs_
  ) ERC721A("Azuki", "AZUKI", maxBatchSize_, collectionSize_) {
    maxPerAddressDuringMint = maxBatchSize_;
    amountForAuctionAndDev = amountForAuctionAndDev_;
    amountForDevs = amountForDevs_;
    require(
      amountForAuctionAndDev_ <= collectionSize_,
      "larger collection size needed"
    );
  }

  modifier callerIsUser() {
    require(tx.origin == msg.sender, "The caller is another contract");
    _;
  }

  function auctionMint(uint256 quantity) external payable callerIsUser {
    uint256 _saleStartTime = uint256(saleConfig.auctionSaleStartTime);
    require(
      _saleStartTime != 0 && block.timestamp >= _saleStartTime,
      "sale has not started yet"
    );
    require(
      totalSupply() + quantity <= amountForAuctionAndDev,
      "not enough remaining reserved for auction to support desired mint amount"
    );
    require(
      numberMinted(msg.sender) + quantity <= maxPerAddressDuringMint,
      "can not mint this many"
    );
    uint256 totalCost = getAuctionPrice(_saleStartTime) * quantity;
    _safeMint(msg.sender, quantity);
    refundIfOver(totalCost);
  }

  function allowlistMint() external payable callerIsUser {
    uint256 price = uint256(saleConfig.mintlistPrice);
    require(price != 0, "allowlist sale has not begun yet");
    require(allowlist[msg.sender] > 0, "not eligible for allowlist mint");
    require(totalSupply() + 1 <= collectionSize, "reached max supply");
    allowlist[msg.sender]--;
    _safeMint(msg.sender, 1);
    refundIfOver(price);
  }

  function publicSaleMint(uint256 quantity, uint256 callerPublicSaleKey)
    external
    payable
    callerIsUser
  {
    SaleConfig memory config = saleConfig;
    uint256 publicSaleKey = uint256(config.publicSaleKey);
    uint256 publicPrice = uint256(config.publicPrice);
    uint256 publicSaleStartTime = uint256(config.publicSaleStartTime);
    require(
      publicSaleKey == callerPublicSaleKey,
      "called with incorrect public sale key"
    );

    require(
      isPublicSaleOn(publicPrice, publicSaleKey, publicSaleStartTime),
      "public sale has not begun yet"
    );
    require(totalSupply() + quantity <= collectionSize, "reached max supply");
    require(
      numberMinted(msg.sender) + quantity <= maxPerAddressDuringMint,
      "can not mint this many"
    );
    _safeMint(msg.sender, quantity);
    refundIfOver(publicPrice * quantity);
  }

  function refundIfOver(uint256 price) private {
    require(msg.value >= price, "Need to send more ETH.");
    if (msg.value > price) {
      payable(msg.sender).transfer(msg.value - price);
    }
  }

  function isPublicSaleOn(
    uint256 publicPriceWei,
    uint256 publicSaleKey,
    uint256 publicSaleStartTime
  ) public view returns (bool) {
    return
      publicPriceWei != 0 &&
      publicSaleKey != 0 &&
      block.timestamp >= publicSaleStartTime;
  }

  uint256 public constant AUCTION_START_PRICE = 1 ether;
  uint256 public constant AUCTION_END_PRICE = 0.15 ether;
  uint256 public constant AUCTION_PRICE_CURVE_LENGTH = 340 minutes;
  uint256 public constant AUCTION_DROP_INTERVAL = 20 minutes;
  uint256 public constant AUCTION_DROP_PER_STEP =
    (AUCTION_START_PRICE - AUCTION_END_PRICE) /
      (AUCTION_PRICE_CURVE_LENGTH / AUCTION_DROP_INTERVAL);

  function getAuctionPrice(uint256 _saleStartTime)
    public
    view
    returns (uint256)
  {
    if (block.timestamp < _saleStartTime) {
      return AUCTION_START_PRICE;
    }
    if (block.timestamp - _saleStartTime >= AUCTION_PRICE_CURVE_LENGTH) {
      return AUCTION_END_PRICE;
    } else {
      uint256 steps = (block.timestamp - _saleStartTime) /
        AUCTION_DROP_INTERVAL;
      return AUCTION_START_PRICE - (steps * AUCTION_DROP_PER_STEP);
    }
  }

  function endAuctionAndSetupNonAuctionSaleInfo(
    uint64 mintlistPriceWei,
    uint64 publicPriceWei,
    uint32 publicSaleStartTime
  ) external onlyOwner {
    saleConfig = SaleConfig(
      0,
      publicSaleStartTime,
      mintlistPriceWei,
      publicPriceWei,
      saleConfig.publicSaleKey
    );
  }

  function setAuctionSaleStartTime(uint32 timestamp) external onlyOwner {
    saleConfig.auctionSaleStartTime = timestamp;
  }

  function setPublicSaleKey(uint32 key) external onlyOwner {
    saleConfig.publicSaleKey = key;
  }

  function seedAllowlist(address[] memory addresses, uint256[] memory numSlots)
    external
    onlyOwner
  {
    require(
      addresses.length == numSlots.length,
      "addresses does not match numSlots length"
    );
    for (uint256 i = 0; i < addresses.length; i++) {
      allowlist[addresses[i]] = numSlots[i];
    }
  }

  // For marketing etc.
  function devMint(uint256 quantity) external onlyOwner {
    require(
      totalSupply() + quantity <= amountForDevs,
      "too many already minted before dev mint"
    );
    require(
      quantity % maxBatchSize == 0,
      "can only mint a multiple of the maxBatchSize"
    );
    uint256 numChunks = quantity / maxBatchSize;
    for (uint256 i = 0; i < numChunks; i++) {
      _safeMint(msg.sender, maxBatchSize);
    }
  }

  // // metadata URI
  string private _baseTokenURI;

  function _baseURI() internal view virtual override returns (string memory) {
    return _baseTokenURI;
  }

  function setBaseURI(string calldata baseURI) external onlyOwner {
    _baseTokenURI = baseURI;
  }

  function withdrawMoney() external onlyOwner nonReentrant {
    (bool success, ) = msg.sender.call{value: address(this).balance}("");
    require(success, "Transfer failed.");
  }

  function setOwnersExplicit(uint256 quantity) external onlyOwner nonReentrant {
    _setOwnersExplicit(quantity);
  }

  function numberMinted(address owner) public view returns (uint256) {
    return _numberMinted(owner);
  }

  function getOwnershipData(uint256 tokenId)
    external
    view
    returns (TokenOwnership memory)
  {
    return ownershipOf(tokenId);
  }
}

Azuki荷兰拍规则

拍卖的第一阶段是荷兰拍卖会，将于太平洋标准时间 1 月 12 日星期三上午 10:00 开始。大约 8700 个 Azukis 将以 1 ETH 的起始价格用于铸造。价格将每 20 分钟下降 0.05 ETH，直到达到 0.15 ETH。 Azuki的荷兰拍模式本质上是一种变种荷兰拍，最后的价格停留在最低价0.15 ETH，这能提高底价，让Azuki获得大量的收入以及避免gas战争。

使用荷兰拍的一些NFT项目

• Azuki NFT

• Art Blocks

• Mutant Ape Yacht Club

• Nanopass

• Pixelmon

扩展阅读

什么是荷兰式拍卖？为什么它在NFT领域很重要？ LBP 与 荷兰拍 Gradual Dutch Auctions - Paradigm YGG IDO 规则变更：将采取荷兰式拍卖！ NFT复盘 Azuki 荷兰式拍卖的缘起及NFT荷拍三大里程碑 英式拍到荷兰拍