Dynamic Envious Preset
Description
In the specification of the ERC721 standard, the tokenId maps to a unique URI using the tokenURI function. This mapping is possible since the tokenURI function is bijective.
In ERC721Envious and EnviousHouse, a new parameter collateral is added to represent the power of the NFT. The tokenURI function is modified to include this new parameter and to update the result of the function on every collateral, uncollateral, and disperse function call. These functions are overridden with additional logic to include the new collateral parameter. This allows for more flexibility and customization in how the NFTs are used and represented.
Hint
Currently, collateral is only measured for the measurementToken, but an upgrade is possible to enable checking of all collateral and achieve a dynamic tokenURI.
The tokenURI function in the template implementation appears as follows:
function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
_requireMinted(tokenId);
string memory currentURI = _baseURI();
return string(abi.encodePacked(currentURI, tokenId.toString()));
}
The results are likely recognizable to most readers and take the form of ipfs://QmeSjSinHpPnmXmspMjwiXyN6zS4E9zccariGR3jxcaWtq/1337 for a specific Bored Ape Yacht Club NFT (in this case, number 1337). This link points to the metadata for the given NFT and consists of two components:
Basic URI (in the example, an IPFS hash)
tokenId for an existing NFT
To make the collection dynamic, it’s only necessary to update the tokenURI function with the following:
function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
_requireMinted(tokenId);
string memory currentURI = _baseURI();
uint256 tokenPointer = getTokenPointer(tokenId);
return string(abi.encodePacked(currentURI, tokenPointer.toString()));
}
The tokenPointer refers to the proportional quantity of the measurementToken.
Hint
Although the GHOST team favors appending .json to every tokenURI, any preferred method will suffice.
To implement the getTokenPointer function, it is necessary to define the edges that correspond to specific groups of URIs. The keccak256 hashing function can then be applied to merge different parameters into one, resulting in the final tokenPointer. An example of the getTokenPointer function is provided below:
function getTokenPointer(uint256 tokenId) public view virtual override returns (uint256) {
uint256 collateral = collateralBalances[tokenId][measurmentTokenAddress];
uint256 totalDisperse = disperseBalance[measurmentTokenAddress] / totalSupply();
uint256 takenDisperse = disperseTaken[tokenId][measurmentTokenAddress];
uint256 value = collateral + totalDisperse - takenDisperse;
uint256 range = 1;
uint256 offset = 0;
for (uint256 i = edges.length; i > 0; i--) {
if (value >= edges[i-1].value) {
range = edges[i-1].range;
offset = edges[i-1].offset;
break;
}
}
uint256 seed = uint256(keccak256(abi.encodePacked(tokenId, collateral, totalDisperse))) % range;
return seed + offset;
}
The initial step is to obtain the amount of full collateral in the measurementToken for a specific tokenId. Subsequently, the iteration through predetermined edges takes place to determine the level at which the collateral amount falls into. Finally, the keccak256 is applied to retrieve a specific value within a predefined range.
John McAfee Legacy (JML) NFT Collection is the first implementation of the ERC721EnviousDynamic preset.
IERC721EnviousDynamic
struct Edge
struct Edge stores the required data for enabling dynamic behavior in the collection, which can be compared to levels in gaming.
_Arguments_
Name |
Type |
Description |
|---|---|---|
value |
uint256 |
minimal measurementToken collateral in edge |
offset |
uint256 |
minimum tokenId in edge |
range |
uint256 |
maximum tokenId range between the edges |
getTokenPointer
function getTokenPointer(uint256 tokenId) external view returns (uint256)
getTokenPointer serves as a tokenURI getter for a specific tokenId, with the edge being determined by the collateral.
getTokenPointer function returns a pseudo pointer to the metadata.
_Arguments_
Name |
Type |
Description |
|---|---|---|
tokenId |
uint256 |
unique token identifier |
ERC721EnviousDynamic
baseURI
function baseURI() external view virtual returns (string memory)
baseURI is a getter function for the baseURI, typically represented by an IPFS hash.
baseURI function returns the prefix for the URI with metadata.
setGhostAddresses
function setGhostAddresses(address ghostToken, address ghostBonding) public virtual
setGhostAddresses function modifies the underlying ghost-related addresses.
_Arguments_
Name |
Type |
Description |
|---|---|---|
ghostToken |
address |
address of a non-rebasing bonding token |
ghostBonding |
address |
address of a bonding smart contract |
changeCommunityAddresses
function changeCommunityAddresses(address newTokenAddress, address newBlackHole) public virtual
changeCommunityAddresses function enables to change the address of the communityToken and the blackHole.
_Arguments_
Name |
Type |
Description |
|---|---|---|
newTokenAddress |
address |
new address of an ERC20 |
newBlackHole |
address |
new address of a |
_changeBaseURI
function _changeBaseURI(string memory newBaseURI) internal virtual
_changeBaseURI function enables to change baseURI.
_Arguments_
Name |
Type |
Description |
|---|---|---|
newBaseURI |
string |
new link prefix |
Gas Report
The complete test results can be found in the ./gas reporter/ERC721EnviousDynamicPreset.txt file. The actual tests are available in the ./tests/ERC721EnviousDynamicPreset.test.js file.
·------------------------------------------------------------|---------------------------|--------------|----------------------------·
| Solc version: 0.8.4+commit.c7e474f2 · Optimizer enabled: true · Runs: 1337 · Block limit: 6718946 gas │
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| Methods │
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| Contract · Method · Min · Max · Avg · # calls · eur (avg) │
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| BadToken · approve · - · - · 46213 · 12 · - │
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| BadToken · mint · - · - · 70691 · 6 · - │
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| BaseToken · approve · 46220 · 46244 · 46241 · 109 · - │
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| BaseToken · mint · 51185 · 68285 · 67982 · 114 · - │
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| BaseToken · transfer · - · - · 46608 · 1 · - │
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| DAI · approve · 46201 · 46213 · 46212 · 59 · - │
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| DAI · mint · - · - · 70713 · 59 · - │
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| ERC721EnviousDynamicPreset · approve · 26672 · 51125 · 44754 · 215 · - │
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| ERC721EnviousDynamicPreset · burn · 46412 · 62487 · 59571 · 15 · - │
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| ERC721EnviousDynamicPreset · changeCommunityAddresses · - · - · 66687 · 2 · - │
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| ERC721EnviousDynamicPreset · claimDiscountedCollateral · 55765 · 182596 · 156257 · 14 · - │
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| ERC721EnviousDynamicPreset · collateralize · 69447 · 466833 · 137521 · 105 · - │
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| ERC721EnviousDynamicPreset · disperse · 72718 · 403232 · 148481 · 31 · - │
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| ERC721EnviousDynamicPreset · getDiscountedCollateral · 158312 · 206589 · 187408 · 23 · - │
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| ERC721EnviousDynamicPreset · mint · 151053 · 162853 · 158041 · 562 · - │
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| ERC721EnviousDynamicPreset · safeTransferFrom · 31313 · 101463 · 84615 · 104 · - │
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| ERC721EnviousDynamicPreset · safeTransferFrom · 32033 · 102625 · 85522 · 104 · - │
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| ERC721EnviousDynamicPreset · setApprovalForAll · 26386 · 46298 · 45350 · 189 · - │
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| ERC721EnviousDynamicPreset · setGhostAddresses · 66774 · 66786 · 66784 · 26 · - │
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| ERC721EnviousDynamicPreset · transferFrom · 30954 · 94056 · 80619 · 56 · - │
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| ERC721EnviousDynamicPreset · uncollateralize · 56897 · 138116 · 90793 · 39 · - │
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| RebaseToken · approve · 46223 · 46235 · 46234 · 59 · - │
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| RebaseToken · initialize · 94307 · 94319 · 94317 · 59 · - │
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| StakingMock · fund · - · - · 61607 · 59 · - │
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| TetherToken · approve · 46232 · 46244 · 46243 · 59 · - │
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| TetherToken · mint · - · - · 68219 · 59 · - │
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| Deployments · · % of limit · │
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| BadToken · - · - · 1140859 · 17 % · - │
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| BaseToken · 775391 · 775475 · 775422 · 11.5 % · - │
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| BondingMock · 1114846 · 1114870 · 1114867 · 16.6 % · - │
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| DAI · - · - · 1148998 · 17.1 % · - │
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| ERC721EnviousDynamicPreset · 4701295 · 4701307 · 4701306 · 70 % · - │
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| ERC721ReceiverMock · 285979 · 286027 · 286014 · 4.3 % · - │
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| RebaseToken · - · - · 1711816 · 25.5 % · - │
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| StakingMock · 246573 · 246585 · 246584 · 3.7 % · - │
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| TetherToken · - · - · 758083 · 11.3 % · - │
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