MAFMan's spherical trig calculator

[MAFman]

I'm trying to make a tool that takes two geocoordinates as input and spits out  the shortest and safest path between the two (as a queue of points from the end to the start) kinda like GPS routing. How do I do that?

[Vanamonde]

Hi @MAFman. Your post has been moved to its own thread. Feel free to edit the post and change the temporary title I have given it. 

[Kerbart]

You can take a look at the haversine formula's for starters. The shortest distance might not be what you want to aim for, as you will likely end up with recalculating your bearing all the time (a course following a great circle rarely ever has a constant bearing).

A loxodrome will give you a constant bearing, which is easier to navigate by (but a longer route. However, getting where you want to be trumps never arriving as you get lost, even if the route is shorter). A loxodrome is a straight line on a Mercator projection, by the way; which is why it's popular with seafarers. As a result it's a popular projection despite its shortcomings on size and shape.

[MAFman]

I was thinking of pulling a heightmap directly from the game and using A* to search through it, using the brightness per pixel (height) and the change in altitude over the change in coordinates as a heuristic, as well as arbitrarily assigning infinite cost to points in the ocean. Currently, I have the HeightMapExtractor mod working on pulling a 32K heightmap (which it's been working on for the last two days...).

[Kerbart]

As far as I know, pixels on the height map translate to lattitude/longitude. So you have to keep in mind that a pixel around 0° lattitude covers a lot more distance than a pixel around 90­° lattitude.

But it’s not a bad idea to use it as a starting base and worry about those issues later once you have something working.