Frmandy
A Fully on-chain NFT mint using Cartesi and Ethereum smart contracts
About
Cartesi is designed for doing computation off-chain that would be otherwise be difficult in the EVM. A Mandelbrot set is a classic example. Although we could generate a Madelbrot set escape time plot in the EVM, writing the resulting PNG file would be a challenge. In this hypothetical example, we make a NFT that sells off portions of the set such as "seahorse valley" (--0.75:0.1:10.0) to collectors. In an ideal scenario, we could use Cartesi to write a file to IPFS and publish the URL on the chain by use of Cartesi's unique voucher system.
How it's made
Rust is the ideal language for these computational loads having a good degree of stability and an established set of libraries such as the PNG library used in this example. The core code of this contract is as follows: fn escape_time(cx: f64, cy: f64) -> u8 { let mut zx = cx; let mut zy = cy; let mut res = 0; loop { (zx, zy) = (zx*zx - zy*zy + cx, 2.0*zy*zx + cy ); if zx*zx + zy*zy > 4.0 || res == 255 { return res; } res += 1; } } We give three parameters to the contract: x, y and zoom. This determines the generated image. In a more complex example, we could composite SVG images to create mutations of comic book characters or sell off images of plots of land on Mars. There is a small demo UI which intereacts with the emulator directly as testing the smart contracts end to end was a challenge given the many moving parts. Hopefully this demonstrates the core concepts. Next step would be to deploy to chain.