#expressive range

The PCG Assistant - Danesh 

Mike Cook’s procedural generation tool has been released!

It’s not a generator, it’s a tool for analyzing generators. Any generator: just set some annotations in the code and it can take the output and settings of any generator function and show you the expressive range. You can track how changes you make to the generator affect the metrics of the output and collect a sample of the expressive range across a large randomized range of input parameters. 

This kind of tool lets us move from feeling our way around individual settings for a generator and gives us a high-level picture of the possible outputs. Often, the problem when making a new generator is maximizing the surprises while minimizing the broken outputs.

For live generators, where we’re sailing in unknown waters without a good map of the possible outcomes, we tend to stick close to shore--only implementing the algorithms that we know will work. Danesh and tools like it give us a map and a compass that we can use to plot our way across the ocean.

Michael Cook: Express Yourself

I’m back from a visit to San Francisco for GDC, where I met a lot of people and had many conversations about procedural generation. Including getting a look behind the scenes of the mythology generation in Moon Hunters and Dwarf Fortress. (Seeing Dwarf Fortress mythologies generated live is something special.) 

But that also means that a ton of procedural generation news has happened that we need to catch up on, starting with a post from Michael Cook’s revived Saturday Papers series, where he takes a close look at a research paper. In this case, it’s “Analyzing the Expressive Range of a Level Generator” by Gillian Smith and Jim Whitehead.

The expressive range of a generator, a term coined in the paper, is about measuring the “style and range” of the generator. Being able to quantify the variety of levels that a generator can create makes it much easier to evaluate the potential output. Instead of looking at a handful of possibly atypical results, we can look at the statistics from thousands of generator runs.

Of course, part of the trick here is to make sure you’re measuring the right aspect of the generator output. There’s some ongoing research in that area as well.

If you’d like to know more about expressive range, both Michael’s blogpost and the original paper are well worth your time.

The Saturday Papers: Express Yourself:  http://www.gamesbyangelina.org/2016/03/the-saturday-papers-express-yourself/