A city you can look at

The city map is the one screen you never leave for long. You plan your day on it, you watch the clock run on it, you come back to it after every scene. For weeks it looked like a pale grey veil over dark blocks, and nothing we tried made it better. We changed colours, fog and lighting for days and kept getting the same flat result.

Today we found out why, and fixed it.

The bug that ate every palette

Every wall in the city was built with its surface facing into the building. To the renderer, the light was always on the wrong side. Facades came out almost black whatever the sun, the sky or the colours did, and every palette we tried died on them.

One line flipped them back. Then the rest of the work started paying off:

• A composed look instead of a raw weather simulation. The day cycle used to wash everything in fog that rain made seven times thicker. The map now has its own fixed exposure and a horizon fade that stays back on the horizon instead of covering the whole city.
• Water and green. Our city files had roads and buildings only, so London had no Thames. The river, the parks and the green spaces now come from OpenStreetMap.
• Trees. About 4,000 of them, along the streets and through the parks, kept out of the river.
• A skyline. Most buildings in our data have no height, so the city was one flat carpet. A share of the larger blocks now rise as towers.
• A ground under the city. It stretches to the horizon, so London no longer sits on a plateau with a hard edge.
• Clean bends. Roads used to break apart at every corner; the joins are round now.

And at night

The same city, with the lights out. Office towers and flats switch on window by window, the main roads glow faintly, and the river goes dark.

By day the same windows stay as dark glass, so the towers keep their detail.

It costs nothing

A map you look at all the time cannot eat your frame rate. We measured before and after: the city runs at the same speed as before this work, around 120 frames per second on our test machine. The new trees are cheaper to draw than the old ones.

Smaller things on the map

• Pins come to you. Places only show their marker when your camera gets close, so the whole city is no longer covered in icons. Closed venues and other people's homes are no longer pinned.
• The minimap now sits under the filters, in one column in the corner.

Fixed

• A crash at midnight. When the day rolled over, the game reset every person's "today" counters. It was changing a person's list of values while still reading through that same list, and sometimes that crashed the game. If your game ever closed as the clock passed midnight, this was it.
• Rooms stuck at 90%. Walking into a venue could hang on the loading bar. Employees were also being dressed in their uniform three times over, which made it slower still. Both are fixed, and people on shift now wear their workplace's uniform.

For modders: the whole map look lives in ul_Base/Map/city_styles.json: colours, fog, exposure, windows, trees, ground, by day and by night. The fields are in the map docs.