It's what's inside that matters: on the generation of procedural organs

This post was originally posted on my personal blog. Excuse all the Twitter embeds, they were just the best way to post the MP4s in here :)

When I enter game jams, I go full crunch mode, which usually ends up in very awkward sleep-deprived Mondays at work. The older I get, the harder it is for me to get hyped enough to do one. Fortunately, PROCJAM is super chill, which makes it perfect for me. Also because cheating is totally okay, which means I can do stuff like necroing my organ generator that I worked on for Bestiarium a few months ago and actually building a prototype around it.

Even though I went through a long time without touching it, Bestiarium has an impressive amount of ideas floating around in my head, but there are a few "philosophical" points where it stands upon. It was always supposed to be a "one room roguelike", so inevitably the exploration space will be less towards the "outside" and more towards the "inside", which makes that William Blake poem fit like a glove:

This sort of thing, to me, ends up being more fun when it's taken on a literal direction. So I guess it's more towards the "insides".

One of the main mechanics of the game would involve extracting materials from the creatures you can summon. I could do the regular thing and just drop "rabit's foot" and "spider eyeball" from them but it's also a game about science, and how science sometimes about trial and error (and most of the times, hard work and elbow grease).

So here was the pitch of a small bullet point marked with "probably wouldn't work" on my design notes: you have to dissect the creatures to harvest elements from them. PROCJAM was obviously a perfect excuse for actually wrapping a prototype around that and test out.

De daemonici corporis fabrica (which is verbatim the demonic version of De humani corporis fabrica) tries to emulate what ancient scholars could have felt when they opened up a corpse for the first time, which was probably some variation of "what the hell is this lumpy, wrinkly thing for exactly?". But I digress. This post is about the tech side, and it all started with... well, how the hell can we generate procedural organs?

It all started many months ago with a night filled with watching animal dissection videos (most research work for this thing reminded me of this Gamasutra article). I could of course just go towards morph targets in a bunch of pre-made organ models. But I had just added a Markov Chain-based name generator to the Invocation Prototype, and that got me thinking: could I maybe use it to generate organs that are more similar to "real" ones?

For markov chains, we need some starting samples:

Yes, incredible 8x8 pixel templates that kind of resemble organs if you squint your eyes. The first thing I did was simply encoding black and white into 0s and 1s in a string, then feeding that into the Markov chain - something that I was pretty sure wouldn't work, but I wanted to try a step by step approach.

Then the time came to texturing, and I again tried to cut corners running away from unwrapping the UV on this thing. I did a bunch of experiments using 3d noise functions (you can get the noise shaders I ported from this repo in a handy, barely tested CGINC for Unity). They looked pretty cool (and I'll probably use it somehow), but the cheap solution got really expensive when I had to generate normal maps out of it.

In the end, just a simple planar UV map (by plotting XZ vertex position normalized into UV space) was good enough, and I could use painted textures (which not only got me grossed out getting photo sources, but also RT'd by Polycount).

Yay, sausages!

Looking back, most of my solutions were maybe overkill and I could probably achieve a better result with a good artist handcrafting all those organs, but it was a fun experiment. In the end, I guess it was mostly about exploring this uncharted territory which, weird as it might be, I'm pretty sure wasn't visited before.

You can play De daemonici corporis fabrica on my itch.io page while I cook up the Vive version, and follow me @yankooliveira to see what I'm up to with Bestiarium.