Generative NFTs

Logic Rules in Generative NFT Sets Help Curate the Art, but Need to Be Understood, As Well

Get them in the code, but be aware of potential consequences.

Whenever I do a generative NFT art project for a client (which you can learn more about here), one area that invariable comes up involves various traits that conflict with one another. Even most simpler generative NFT sets have such things, and that’s perfectly fine. It could be something as simple as “If the background is black, then disallow black hair on the character.” But, quite often the logic rules can become more complex, depending on various aspects of the art.

For me, I see logical rules as being a natural extension to generative NFTs. They allow the artist to curate the set, while maintaining the randomness desired.

That said, it’s also important to understand that logical rules do have an effect on the rarity table. Often, on a 10k run, such an effect may be immaterial (thankfully), but there’s definitely a potential for a material effect. Let me explain by example:

Let’s say you have a cat with two paws that always show. Those paws can each be in two positions — up or down. And, for this trait, you set it to pure randomness, a 50% probability that either paw will be up or down. So, that’s the key thing to remember here: We have set the rarity table at 50% up / 50% down, and that would be the expectation in the generated set. (Info on how to make a rarity table here.)

So, we run the 10k set, and we see all of the wonderful characters. As expected, ~50% have paws up (left or right), 50% have paws down (left or right). The percent that have both down, both up, one-up/one-down, one-down/one-up would also likely be fairly equal.

With me so far? Ok, now let’s add in a logical rule:

If the LEFT paw (chosen first) is UP, the the RIGHT paw must also be UP.

See where I’m going with this? So, let’s run another 10k and see what happens (same rarity table, but with this new rule applied to the generative code). What’s going to happen here is that, indeed the LEFT paw will be ~50% up / ~50% down. BUT, on that first (left) 50%, we now have a rule that says that the matching RIGHT paw…