getCombinedDirectionSegments

This is based on the original iOS COMBINED direction type which they described like this:

Ahead, Right, Behind, and Left all get a 150 degree window centered in their respective directions (e.g. right is 15 degrees to 165 degrees). In the areas where these windows overlap, the relative directions get combined. For example, 0 degrees is "ahead", while 20 degrees is "ahead to the right."

However, this gives a very small Ahead window which leads to less good intersection descriptions, especially when all ahead/behind Left are reduced to Left. As a result, we've biased ahead over ahead left/right so that it's 60 degrees, and the ahead/behind left/right are only 30 degrees. This is basically shrinking the 150 degree window to 120 degrees.

Parameters