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[Whiskey_Sierra_972]

Hi mates!

I have to resume this old tread....and doing this I can feel also how much Eugen aka SAS~Malone is missing here....

As I'm looking at some maps stuff , can I ask if atm the actual value of DECLIN for game is the latitude or the azimuth?

I've tested the different value in Somme winter central location (Roye) that have a latitude of 49.7 N

The difference between this value and the calculated azimuth (30,2) as in post 6 edit is noticeable....

As I think to restart my interrupted work about maps WORLDPOS harmonization (that was interrupted due RL issues 8 years ago ans also due the different value about DECLIN supposed to be).....I need to finish the affermation posted by the great WxTech in the last post....

[Whiskey_Sierra_972]

Doubt solved:

https://www.sas1946.com/main/index.php/topic,20264.msg484416.html#msg484416

As BAT have inside the Variable Temperature mod by Western (which was incorporated in the engine mod) the value must be added in latitude NOT azimuth....

[Whiskey_Sierra_972]

Anyway I've done a test and discover that no difference there are between various settings...

Any clue about or comparative tests?

RESULTS OF MY TEST:

Map: Somme winter
Date: 15 novembre 1916
Location: Roye airfield take off direction 90°
Location as real longitude (in decimal degrees): 49.7
Location sun azimuth: 21.61
Location as azimuth formula in post 6 [(90-21.61)x0.75] = 51.3
Location as azimuth: 68,39

Sunrise as per https://www.suncalc.org/#/49.6978,2.7891,13/1916.11.15/12:00/1/3 at 07:00

TEST 1 with DECLIN as longitude SUNRISE at 07:30 - CULMINATION at 12:00 see picture 1 - SUNSET at 16:28

TEST 2 with DECLIN as azimuth SUNRISE at 07:30 - CULMINATION at 12:00 see picture 2 - SUNSET at 16:28

TEST 3 with DECLIN as 90-latitude (without correction) SUNRISE at 07:30 - CULMINATION at 12:00 see picture 3 - SUNSET at 16:28

I can't calculate the real angle of the sun at his azimuth....but I post the images taken at 12:00 for the 3 situation so you can chech how the sun seem have alwys the same height at his peack...moreover is strange that there isn't any variation in sunrises and sunsets....

TEST 1



TEST 2



TEST 3

[WxTech]

Looking at the code in Sun.class makes it clear that DECLIN is the latitude. And this value applies to the entire map, no matter how large.

There is zero consideration of longitude. All places will experience sunrise/set at the same time.

To put it this way, from the standpoint of the disposition of Sun and Moon our maps are treated as though they occupy just a dot in the game world.

When undertaking map tests, it might be wise to load a different map after making a change to load.ini, then load your map under test. Just to be completely certain that the entirety of the updated values are applied.

Another thing. I've got into the habit of writing the lines without space characters. Such as

DECLIN=45

I have encountered oddities which such a practice appears to fix. I don't see why this should be the case, however... 😉

[Whiskey_Sierra_972]

I have done a further test about sun height....setting DECLINE at 10 and after at 80....

With 80 the sun is just at the horizont a 12 o'clock while at 10 the sun is very high....so definitively it work....

About testing I have always closed the game and reloaded it after every change in load.ini DECLINE....

I'll retry tomorrow....

[taly01]

Many map .ini DECLIN are not anywhere near the true latitude value, they seem to use 10 a lot, which would give a nice consistent day length all year.  I never bothered to check before seeing this thread 

I mostly use DGen_mod and there is an option to set length of night by clock time, and it does work.   But I need to test if it just forces the suns declin path from the maps .ini to move at that fixed rate.

[Whiskey_Sierra_972]

IIRC this future in DGen is for starting time missions...no take off before set daylight time and night mission from sundown....

[taly01]

IIRC this future in DGen is for starting time missions...no take off before set daylight time and night mission from sundown....

You are right, my logic was wrong, it "changed" how much sunlight in missions by forcing them to start in daylight.

I did some DECLIN tests for latitude values 50, 0, -50
for June and December at 1200
The midsummer/midwinter sun was in the correct position and month for 50 Northern hemisphere, and -50 southern hemisphere, and 0 Equator made no visible difference in sun.

I could check dawn/dusk sun movements, but the DECLIN system does appear to work as a Latitude .

[Seppel]

I do not think, that the angle of the sun determines the length of the day?
But it should influence the daylight!?

The DECLINE - as I know and understand it- only determines the shadows of objects and maybe sun blinding if you fly in a certain height or angle.
AND of course the sun shouldn't be in the south when you flying over Australia f.e. :-D


When building maps, I googled the sun angle at a central position or town in the map and typed it in the decline line.
But the effect may be marginal.

[taly01]

I googled the sun angle at a central position or town in the map and typed it in the decline line.
But the effect may be marginal

I think confusion was created by the name Declin(e).  It sounds like the suns angle but as WxTech showed Declination is an astronomical word for Latitude.   Also the code shows it is latitude, and the sun correctly moves seasonly when latitude is used.   The good news is it also simplifies things to just put the latitude into Declin and it works all year round.

[Whiskey_Sierra_972]

The sad thing is that in 2015 I've updated the decline of all maps but suspended works waiting which was the correct angle to set....and also added the correct climate value....

....and now I'm no more finding all that work!

https://www.sas1946.com/main/index.php/topic,55864.0.html

[WxTech]

A couple years ago I went through all B.A.T. 4.0 maps for which a location could be determined and provided more correct DECLIN values in a spreadsheet table. I can make that available.

Of course, in cases where careers have been constructed, where a large change is made this can have some impact on Sun and Moon disposition and the duration of twilight.