Day-Night Cycle in Civ 3, using C3X 1

This mod introduces the Day/Night Cycle in Civ 3, similar in spirit to its implementation in Civ 6. The mod is implemented as a feature in the forthcoming version (R25) of C3X.

To use the Day/Night Cycle:

1. Install the R25 or later version of C3X.
2. Download the Day/Night Cycle artwork from the Google Drive link. (please note at ~180MB compressed, the .zip file is too large to upload directly to CivFanatics, which I'd prefer)
3. Unzip under /C3X/Art/. This should create a new folder, "DayNight", with subfolders for "0100", "0200", and so on (24 total, one for each hour of the day).
4. In your C3X settings file, set day_night_cycle_mode to one of the following (default value is off):
   1. timer - Increment based on time elapsed since last hour transition (e.g., transition to next hour every 3 minutes)
   2. user-time - Match the user's system clock to determine hour of the day
   3. every-turn - Increment every turn by a fixed amount of hours
   4. specified - Pin the hour to a specific value (so hour of day is always the same)

Details can be found in the C3X configuration file. Note that the Day/Night Cycle should not be enabled if you are using non-standard terrain art or resources. Doing so may result in visual glitches or missing sprites. Also note that loading the Day/Night Cycle art may add ~5-10 seconds to the initial progress bar load time (e.g., after you click, "New Game"), though I have not yet noticed any slowdown in the game itself when the art changes.

In a nutshell, the Day/Night Cycle is implemented by:

1. A set of Python scripts which, for each hour (and using many, many knobs and variables I've tested), impute slowly changing colors for daytime, evening, twilight, dawn, and so on. The base game art (unchanged) is used for 12pm (noon).
2. I (by hand using gimp) annotated various "light key" PCX files, with special colors drawn over the base art. These are cued in on by a subsequent Python script which imputes flared and glowing lights in various colors, simulating nighttime lights. Steps 1 and 2 are run via a script once to generate the hourly art (only once, before the game is started. You don't need to do this step, as the download contains all files needed).
3. At runtime, C3X activates "proxy sprites", whereby at each transition, the game checks if a given terrain, city, resource, and so on have a Day/Night proxy sprite they should show instead. If yes, the game draws that.

Example screenshots:




Time transitions:


I welcome any feedback you have, and am indebted to Flintlock for help, advise, and debugging of the Day/Night Cycle implementation. This was a team effort and I sincerely hope you enjoy the mod (with more fun things to come!). The conversation and thinking behind this is detailed in the C3X source code repository issue here.

Please note I am not fully satisfied with the modern era art, and am working to balance the color variation unique to each game culture (e.g., modern buildings with blue, green, or other colors) vs. a more balanced yellow/white flared light look. Please let me know what you think.