Deploying a uERC721 in any EVM chain
Once a sibling collection has been created, its assigned contractAddress in LAOS can be used to deploy an ERC721 collection, in any EVM blockchain of choice (such as Ethereum or Polygon), which will be paired with the sibling collection.
The pairing is established by using the Universal Location, a feature of Polkadot's Cross-Consensus Messaging version 3. Check the videos linked in the References section for a deeper understanding of the Universal Location.
The uERC721 contract
The open-source uERC721 template contract may be used as a starting point to deploy a collection in any EVM of choice. This contract minimally extends the default, audited and widely used ERC721 implementation by OpenZeppelin; the u prefix in uERC721 stands for such a Universal extension.
The extension follows the specification detailed in this Github issue, which will soon be submitted as an ERC proposal.
The only mandatory difference between an ERC721 ready for bridgeless minting and any other ERC721 is that the tokenURI must point to the LAOS consensus system. All other aspects of the uERC721 template are optional. You can use your existing contracts, wrappers, etc., as long as the tokenURIs point to LAOS
The template contract requires a key parameter in its constructor: baseURI. This string specifies the Universal Location of the sibling collection in LAOS. As explained here, the baseURI that would point to a sibling collection in LAOS Sigma Testnet at a given contractAddress is:
Warning: do not forget the trailing slash / at the end of the string
In this particular implementation, the baseURI can be changed by the owner of the contract, which is an address provided in the constructor too, by calling the updateBaseURI method.
The contract also allows the owner to relinquish this privilege and permanently lock the current baseURI by calling the lockBaseURI method.
Please consider this implementation as a template. Feel free to modify and extend its logic to suit your particular needs.
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