The link for "Connections" (I've been calling them geo-graphs or network maps) seems to be broken, which is a shame. I've had a hard time finding good libraries for them, and they're hard to get right for a few reasons:
- if you zoom out to show the world, map projections wrap around the antimeridian (e.g. you turn right at Kamchatka, loop around and hit Alaska.) if you want your edges to wrap (i.e. follow a great arc) rather than taking the long way around (i.e. drawing a line all through Europe and Asia), you have to do spherical math.
- if you want a multigraph (multiple edges between any pair of nodes), you need to have a way for those edges to "curve" rather than following a straight path (great arc.) this makes the math much more complicated, especially keeping numerical stability and accounting for coordinate singularities.
- now imagine all the fiddly bits of making the arrowheads touch the nodes at the right place, scale in width properly, etc. if you're really committed, you'll use lat/lon for every vertex of every poly you render. if not, there will be distortions. it's a trade-off.
- now imagine updating all of that while panning and zooming, and keeping it efficient and smooth.
I made a component for this, I'll try to open-source it, but I'm curious how other people have tackled the same issue. Did I just over-engineer the hell out of it doing spherical trig, vector math and iterative methods, or is it plain hard?