How to determine the season of the terrain
In this tutorial it is described how you can code seasonal changes for your object. As an improvement over using the 6F8 variable it is mentioned there that you can also check the day of the year. But how can you find the correct dates for the changes of the season in your area?
To do so you will need to use TMFViewer, which comes with the Terrain SDK. In the TMFViewer open the file seasons.bgl, which you will find in scenery\base\scenery. Using View -> Seasons you can now switch between the 12 seasons (months) that the default landclass scenery uses. The colors represent the season used at a certain location.
Below you see 12 images attached for the northwestern part of Europe. The colors match the seasons like this:
SP yellow SU green FA red WI grey HW white
The last remaining link before you can start coding is the days at which the different seasons start. Gerrish Grey has provided me with the following dates:
Season Start 038A End 038A 1 15/Jan 15 14/Feb 45 2 15/Feb 46 17/Mar 76 3 18/Mar 77 17/Apr 107 4 18/Apr 108 18/May 138 5 19/May 139 18/Jun 169 6 19/Jun 170 19/Jul 200 7 20/Jul 201 19/Aug 231 8 20/Aug 232 19/Sep 262 9 20/Sep 263 20/Oct 293 10 21/Oct 294 20/Nov 324 11 21/Nov 325 21/Dec 355 12 22/Dec 356 14/Jan 14
If I take a place at the left bottom of the images attached, this would for example lead to the following days for the seasons:
77-169 spring 170-262 summer 263-324 fall 325- 76 winter
As you see this area does not have HW by default. You can now use these days to code the seasonal changes, as described in this tutorial.