Love, Death & Math

Voronoi map generation in Civilization VII Without getting too technical, the Voronoi technique completely changes how we approach map generation. Previously, fractal noise had been used to create maps, and it works really well when it can be applied uniformly to the whole map. That said, it can be hard to steer towards specific gameplay needs. Voronoi diagrams, on the other hand, give us structure we can build rules on top of, so maps can stay organic while still meeting the gameplay requirements of Civ VII. Let's walk through how this works. - Randomly spray a bunch of points onto the map. The more points we spray, the higher the resolution. We'll start low res. - Draw lines around each point dividing them into "cells." You end up with something that looks a bit like cracked glass. - Select some starting cells. These are the seeds of tectonic plates in the game map, similar to the tectonic plates that form our Earth. - Each plate grows, one cell at a time, following some configurable rules, until the whole map is filled. Each plate gets a rotation and movement direction. This is your map's crust, and will be used to help influence the growth of continents later. - Now spray many more dots for a higher resolution version! Draw those lines again to get another shattered-glass look sitting on top of your tectonic plates. - Choose some new starting points for the primary landmasses, and grow them once again following a custom set of configurable rules. These rules can do things like influence landmasses to grow along plate boundaries (especially if they're colliding), avoid the poles, and prefer certain latitudes, just to name a few. This is also where we can apply gameplay-based restrictions, like ensuring Homelands and Distant Lands are separated by a Deep Ocean. - Based on the map's settings, we then grow islands, erode the coastline, add mountains and volcanoes, and perform other finishing touches. Many of these steps involve the same set of generic rules used earlier to determine where features are placed. - Once finished, we overlay the hex grid and then hand the map off to the gameplay layer to determine tile types, Yields, Resources, starting location, and more. The result is that the maps are far more varied and look much more natural. Things that were impossible before can now appear regularly. For example, Homelands and Distant Lands might be North and South of each other. Continents may share a large border, be connected by a small isthmus, or be separated by a sea. There may be a chain of islands between Homelands and Distant Lands – or maybe there won't! The islands could all be clustered in a corner or scattered around, and they're even allowed to merge, possibly causing a continent-sized super-island! https://civilization.2k.com/civ-vii/from-the-devs/map-generation/