Skyrim

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Mikey

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mikeynexus

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About this mod

Uses real astronomical calculations to edit the game settings for dawn/sunrise/sunset/dusk and the height of the sun in the sky, all based on the in-game day of the year and character location. Can also set the game to eternal night or day. Full release (formerly "Accurate Astronomy").

Permissions and credits
Donations
Dedicated to GamerPoets for the best tutorials and immersive roleplay videos around.

Sept/2017: Now in beta testing!!! Thanks to the awesome LogicDragon, an SKSE plugin that automatically detects player location and day of the year and adjusts daylight hours dynamically! No fiddly .exe to run, no MCM required, not even an .esp in your load order. An upcoming release of my stained glass lanterns mod will use this functionality to switch fixed lanterns on/off with the diurnal cycle.

This mod is now available for Skyrim SE, and has none of the lighting problems of this version, due to the new Skyrim SE engine. It even works with ENB!

ENB users: Be sure to read the Known Issues section!

V1.2 fixes a bug whereby the ENBseries.ini was not being updated properly - sorry about that.

V1.1 is a small update that makes the code a bit more robust so it can deal with the new DawnDuskEnable setting in ENB.305. It no longer relies on the lines in ENBSeries.ini being in a particular order or spacing, so you can have comments between lines if you want to make a note of your default/favorite settings.


What this mod does


This mod takes your in-game date and location and uses real-world astronomical calculations to find;
  • sunrise/sunset times,
  • dawn/dusk durations,
  • the maximum height of the sun above the horizon at local noon.

It then edits the accompanying ESP file, and - OPTIONALLY - your ENBseries.ini file to apply these settings to your game before you start a session.

By running this mod at the start of each playing session you can keep these settings as up-to-date as you wish. Running it once every in-game-week will provide a nice sense of transition, but you should also run it if you have travelled significantly northward or southward since you last ran it, especially in Winter or Summer.


What this mod does not - and cannot - do

This mod does NOT alter these settings as you are playing the game. Unfortunately there does not appear to be any way to modify these settings dynamically as you play. If it were possible I would have written it to change the settings after every hour of game time, or after every load screen or cell transition, but, alas, I'm told it can't be done.


It also does not modify these settings for Sovngarde, Apocrypha, or Soul Cairn, as they are on alternate planes of existence.

How to use this mod

After installation and setup (see the instructions below) the process is very simple;
  • Run the executable program that comes with the mod,
  • Enter your in-game month, day and location in the dropdown menus,
  • Choose which of the settings you want updated automatically,
  • Click the "GO" button and any other buttons for settings you want to change,
  • Run Skyrim as you normally would.

At the end of each gaming session you should make a note of the in-game date and your location so that you can enter these at the start of your next session.


Installation

Your ENBseries.ini will automatically be backed up BEFORE this program changes it for the first time, but you should also make your own backup. The lines in [TimeofDay] will be overwritten by this mod if you choose to let it UpdateENB.

Mod Organiser Users

  • Download and install the mod as you normally would.
  • In your modlist activate "DaylightHours" and in your load order activate "DaylightHours.esp".
  • Go to the folder where the mod is located and find the "DaylightHours.exe" executable file. Run this executable.
  • Click on "Settings" and follow the dialogues to locate your "locations.txt" (should be in the mod folder), "DaylightHours.esp" (should be in the mod folder) and "ENBseries.ini" (should be in your Skyrim folder).
  • The program is now set up! Enter the month, date and location that your character was in at your last saved game (See the FAQ if you can't find your location in the list).
  • If you trust the program to do everything automatically, tick the appropriate checkboxes and click "GO".
  • If you are cautious, disable the checkboxes, review and update each setting using the buttons on the right.
  • Next time you run the program, it should know where all the files are and not ask for them again. If it does ask again, let me know.
  • You can keep the executable as a shortcut on your desktop or link to it on the Windows taskbar. It won't work if you try to launch it from M.O. - I'm not that clever.

Manual Installation

  • Think about using Mod Organiser. ;) Actually, it's very easy to use manually, because changes are performed by an executable.
  • Unpack the mod's files.
  • Put the "DaylightHours.ESP" in your Skyrim\data folder.
  • Put the "Locations.txt" file in your Skyrim\data folder.
  • Put the "DaylightHours.exe" in your Skyrim\data folder.
  • In your Skyrim\data list (you know what I mean), activate the ESP.
  • Run the "DaylightHours.exe" executable.
  • Follow the instructions for M.O. users above from point #4 onwards.
  • Keep a shortcut to the executable somewhere handy so you don't have to find it every time.

Load Order

  • Put it wherever you like and if it doesn't work move it lower.
  • I know that some other mods - especially Winterisation mods - change the sunrise/sunset times, so you will need to place it after those.
  • The mod only changes game settings, so it should not conflict with much else because it doesn't actually do anything while the game is running.


Known Issues

For the variable sun position, ENB is the major issue, I'm afraid. It's well known that changing the fsunYextreme value will break ENB's outdoor lighting. It kills sunrays and - more importantly - wrecks night time lighting by causing a permanent half-light across the night sky. This is manageable if the fsunYextreme is kept pretty close to its default value of 40, but this mod will routinely send it to -200 to -1600 (Winter solstice in Solitude). The higher the magnitude, the more extreme the disruption. This problem does not occur when setting the game to eternal night or day.

I'm using Vivid ENB; maybe another ENB will have less of a problem, but I don't know.

To avoid this issue, if you are using ENB lighting you should tick the "UseDefaultSunPosn" box and "AutoUpdateSunPosn" to force it.

But if you don't use ENB lighting there's no problem! Sun position works perfectly! I don't know what effect lighting mods like URWL, RLO and ELFX will have; let me know.

I have heard from Boris@ENB that this problem is simply not fixable, as ENB relies on the sun position for some important processes. I am releasing the mod anyway because;
  • Not everyone uses ENB lighting, so they'll get the full benefit,
  • If the mod becomes well known then someone with far more ENB expertise than I (i.e. >0) might be interested enough to have a go at tackling the problem of night-lighting by tweaking settings.
  • It's still pretty cool to have variable day/night length, even if the sun always follows the same path.

Other Issues

  • Because the sun shrinks unrealistically at very high fsunYextreme settings, I have limited the solar elevation to a minimum of 3 degrees. This does not affect 24hr day or night.
  • Pre-dawn may appear very bright depending on your ENB settings; it may get bright long before you see the sun, especially in midwinter when dawn/dusk can last over 3 hours each.
  • I can't get dawn/dusk light to pay attention to mountains. Morning light will kick-in as soon as the sun is above the horizon, even if blocked by mountains.
  • If you set to 24hr day, the sun will rise to zenith and then vanish, immediately reappearing on the horizon.
  • As the length of the day increases - and especially during 24hr daylight - the sky is badly washed out with my ENB turned on; your mileage may vary. Sorry.

If anyone has any suggestions for solving these issues I'd be happy to hear them.


F.A.Q.

Q. Can you make this a real mod so that it runs when I'm playing the game?
A. Nope. Not unless you can tell me how to update the settings in game. As far as I know it can't be done.
A. I couldn't, but someone very generous and with real skills has figured it out. This is now in beta testing.

Q. My location is not on the list! How can I add it?
A. If you know where you are on the map you can find a location with the same latitude (north-south position) and use that. For example, if you are somewhere in the wilderness, far from landmarks, but you think you are roughly as north as Whiterun, then select "Whiterun" from the dropdown. You can also edit the locations.txt file and add custom locations and latitudes. Make sure you add them to the top or the middle but NOT the bottom.

Q. I have found mistakes in your locations.txt file, or I have some more locations to add.
A. Awesome! Post the data in the forum if you want to and I'll add it to the mod. Or, publish it as your own 'patch' and get some credit! :)

Q. Can you fix the problem with ENB lighting?
A. No. Boris Himself tells me it is not fixable: The Oracle has spoken. It might be possible to minimise the impact at night by tweaking settings but I don't know enough about ENB to try. I love ENB so it's something worth working on.

Q. How does it handle timezones?
A. Yeah, bugger that. Earth didn't have standardised time zones until 1884 (1911 if you include the Paris anomaly), due to the proliferation of railroads, so Skyrim is nowhere near advanced enough to worry about timezones. Wherever you are, local noon is at 1200HRS and local midnight is at 0000HRS.

Q. Where did you get the values for latitude for each location? Are they lore friendly?
A. I combined this spherical projection of Nirn with GameBanshee's awesome map to produce the map of latitudes in the Images section. I later added locations from Klarix's excellent map of Solstheim (permission granted - much kudos). 

Some say Tamriel is smaller than Australia, bigger than Alaska, smaller than Malta, or that Nirn is about half the size of Earth and Tamriel half the size of Eurasia. I don't care; I just wanted daylight hours to vary with location and season for a more immersive game. If you want to rewrite all the latitudes to suit your own vision of Nirn, that's awesome. The match between areas of similar climate, vegetation, and latitude between Earth and Tamriel is pretty good, but Tamriel seems much harsher for latitudes above 60 degrees (Helsinki).

If there's any interest, I might release alternate "Locations.txt" files that reduce or increase the seasonal lighting changes with increasing latitude, to simulate a softer or harsher climate.



Credits

Although I have not used any assets from any other mods, I would like to thank some people whose resources and help made things easier for me.

GamerPoets for inspiring me to create a mod focused purely on immersive gameplay, and for his amazing tutorials on installing and running Skyrim and its mods. A year ago, I didn't know mods existed.

Zilav for dropping the hint that day/night times could be changed from the CK. If you just want eternal night/day, use his mods instead as they are much simpler to use.

GameBanshee for his map.

Klarix for his map.

Prometheus for his globe of Nirn.

Boris for replying to my question about ENB.

Phinix for answering a very early question I had when wondering if this was even possible.

Bethesda for Skyrim and the CK.

Permissions

This mod took a lot of research to create. If you're willing to wade through it in order to make an improvement then good for you; go for it. But don't try to use it to make money, please. And contact me before writing a patch because I can probably just include it in a new release.