Dev Diary #177 - A Fresh Coat of Paint

Welcome to another summer Dev Diary! As the Swedes are lazily shuffling in the door after vacations, we’ll be discussing the map visuals. My name is Petter Lundh. I’m the Art Director for Crusader Kings III for the last two years, previously 2D Lead (my work might be most familiar in the form of the Iberia, Tours, and Persia loading screens)

For All Under Heaven, we're undertaking our most ambitious expansion yet: extending the map to encompass all of Asia. This represents a big undertaking that goes beyond just extending the geography.

While the map has seen new assets trickle in since release, the overall look remains unchanged. During those five years we’ve filled a big bucket of visual ideas we’re eager to implement though, and this expansion proved the perfect opportunity to give the entire map a facelift.

This is mainly an artistic reimagining and a modernizing of our workflow. It doesn’t involve fancy new engine tech—we’re using the same features that have been available to the modding community already. This means you’ll be able to put your own spin on these changes, provided you’re up for tinkering with shader code (or coerce ChatGPT to do it for you).

We also plan to add additional documentation that will make it easier for new modders to get started, though this may come later. Moreover, we're adding optional settings for some of the larger changes that impact performance.

Terrain Workflow

In the olden days (CK3 release), we painted heightmaps and terrain masks by hand. This took our team months to complete, and any increase in detail would exponentially increase the workload. This process leaves little room for iteration and course correction underway.

The old mountains were created mostly from a tiling normal map. This technique results in visual noise in dense mountain regions—something especially apparent when extending the Himalayas eastward. We would rather have a more realistic appearance that mimics real erosion patterns. Mountains should feel more like real mountains.

We adopted the terrain generation software Gaea to solve this problem. It’s a tool that creates realistic heightmaps and material masks through simulating real erosion patterns. We can generate complex terrain far more efficiently than with manual painting, and we no longer have to start from scratch when iterating on the general look.

The scale of terrain features remains largely the same. There’s a few reasons for this:

• We used the old heightmap as a base since the shape of the map also has gameplay implications.

• We find that the stylized scale of mountains look best when zoomed in, even though a more realistic scale can feel better zoomed out. If we adopted a real world scaling, most mountains would appear as noise when zoomed in (at the level where you can actually inspect the terrain).

Here’s what the process looks like:

1. We divide the input heightmap ocean masks into tiles.

2. Each tile gets processed through Gaea, which outputs a final heightmap, overlay colormap and masks for the individual tiling materials.

3. All the output tiles are then stitched together, leaving us with large texture files that cover the entire map

As an extra complication we have divided the world into 7 biomes that each have their own set of tiling textures and material masks that define its character. The above steps are run individually for each biome, and stitched together at the very end to create the final map.

For each biome, we’ll gather references and attempt to extract some unique color palette that makes