On procedural generation

One of my favorite uses of code is to create things. It always has been. When I was young, I was fascinated by fractals and terrain generators and the like. The whole idea of making the code to make something else always appealed to me. Now, as it turns out, the rest of the world has come to the same conclusion.

Procedural generation is all the rage in games these days. Minecraft, of course, has made a killing off of creating worlds from nothing. No Man’s Sky may have flopped, but you can’t fault its ambition: not only was it supposed to have procedurally-generated worlds, but a whole galaxy full of aliens, quests, and, well, content. That last part didn’t happen, but not because of impossibility. The list goes on—and back, as Elite, with its eight galaxies full of procedural star systems, is about as old as I am.

Terrain

Procedural terrain is probably the most widely known form of generation. Even if you’ve never played with TerraGen or something like that, you’ve probably played or seen a game that used procedural heightmaps. (Or voxels, like Minecraft.) Making terrain from code is embarrassingly easy, and I intend to do a post in the near future about it.

From the initial generation, you can add in lots of little extras. Multiple passes, possibly using different algorithms or parameters, give a more lifelike world. Tweaking, say, the sea level changes your jagged mountain range into an archipelago. You can go even further, adding in simulated plate tectonics or volcanic deposition or coastline erosion. There really are no boundaries, but realism takes some work.

Textures and models

Most 3D modeling software will give you an option to make “procedural” textures. These can be cool and trippy, especially those based on noise functions, but it’s very difficult to use them to make something realistic. That doesn’t stop them from being useful for other things; a noise bump map might be more interesting than a noise texture, but the principle is the same.

Going one step up—to actual procedural models—is…not trivial. The “creature generators” as in No Man’s Sky or Spore are severely limited in what they can do. That’s because making models is hard work already. Leaving the job in the hands of an algorithm is asking for disaster. You’re usually better off doing as they do, taking a “base” and altering it algorithmically, but in known ways.

Sound

Procedural sound effects and music interest me a lot. I like music, I like code. It seems only natural to want to combine the two. And there are procedural audio packages out there. Making them sound melodic is like getting a procedural model to work, but for your ears instead of your eyes. It’s far from easy. And most procedural music tends to sound either very loopy and repetitive, or utterly listless. The generating algorithms we use aren’t really suited for musical structure.

Story

Now here’s an intriguing notion: what if algorithms could write a story for us? Creating something coherent is at the high end of the difficulty curve, but that hasn’t stopped some from trying. There’s even a NaNoWriMo-like contest for it.

On a smaller scale, games have been making side quests and algorithmic NPCs for years. That part isn’t solved, but it isn’t hard. (For some reason, Fallout 4 got a lot of press for its “radiant quests” in 2015, like it was something new. Though those are, I think, more random than procedural…) Like modeling, the easiest method is to fill in parts of a pre-arranged skeleton, a bit like Mad Libs.

Anything else

Really, there’s no limit to what can be made through procedural generation. That’s probably why I like it so much. From a small starting seed and a collection of algorithms, amazing things can be brought forth. In an age of multi-gigabyte games full of motion-captured animation, professional voice talent, and real-world scenery, it’s a refreshing change to make something beautiful out of a few letters and numbers.