Aavegotchi stores a lot of information onchain, such as the Aavegotchi's unique name, the numericTraits
about the Aavegotchi, and other details. But unlike many NFT games, we actually store all of the SVG files themselves onchain.
SVG data are stored and retrieved with SvgFacet.sol
and LibSvg.sol
.
It costs less gas to store SVG data as contract data than to store it in contract storage. Normally contract bytecode is stored as contract data, but it is possible to store other data as contract data, as we are doing with SVG data.
This function is used to store SVG data:
struct SvgTypeAndSizes {bytes32 svgType;uint256[] sizes;}function storeSvg(string calldata _svg, SvgTypeAndSizes[] calldata _typesAndSizes)publiconlyDaoOrOwner
The _svg
argument holds one or more SVG images as strings. It is more gas-efficient for _svg
to contain multiple SVG images because _svg
is stored as the entire contents of a contract. Creating a new contract has an up-front fixed gas cost of 32,000.
_typesAndSizes
is used to say what category the SVG images are and contains size information so the _svg
data can be broken into multiple SVG images.
svgType
specifies the category of SVG images in _svg
. Each SVG category has SVG images with unique incrementing identifiers that start at 0. SVG categories are used to distinguish different groups of SVG images. Here are SVG categories:
aavegotchi
collaterals
eyeShapes
wearables
The storeSvg
function above calls the following function to actually store the _svg
argument as contract data:
function storeSvgInContract(string calldata _svg)internalreturns (address svgContract) {
storeSvgInContract
contains the bytecode of a contract constructor function that returns data as a contract. storeSvgInContract
uses the constructor function to create a contract consisting of _svg
and returns the Ethereum address.
External functions call the getSvg(bytes32 _svgType, uint256 _id)
internal function from LibSvg.sol
to get SVG data. _svgType
is the SVG category. _id
is the unique id of an SVG image.