I understand this is a broad topic that to a degree was answered in previous questions.
What I'm trying to do is to create a plugin in Unreal 4. I'll start by creating a day/night system and a skysphere as realistic as possible and then move on to climate, biomes etc.
While to some degree I understand about how to create a sun sky orbit based on geo coordinates that has the right elevation for the sun and the day length, what I don't know is how the rising and setting horizon spot works. I know that it's exactly on east/west on equinoxes and the furthest away on solstices, what I don't know are two things. How the distance between equinox and solstice horizon spots are calculated and what happens in between?
Is it a standard number? And how do I find that? Once I find that is it a simple lerp between the two spots? Or on some days it changes less than on others?
For the star chart should it simply follow the sun movement?
After that I'll move to climate zones... Anything else that has to do with the sun or the moon that I should keep in a table or a variable to be reused that affects the climate zones besides the axial tilt, the rotation period around the sun and the distance from the sun?
While the system will be used for the earth mostly I'd like to have open sliders so I could use it for another planet in the future with different distance from the sun different axial tilt different type of star etc.
Thanks for the help and your time!