Drop shortest distance calc for waypoints and manage their position in the query by route segments

[tristen]

It's otherwise a performance kill calculating the shortest distance between them

[tmcw]

Why does this calculate client-side anyway? We just launched an API for this.

[jfirebaugh]

I'm confused as to why this is necessary at all. mapbox-directions.js doesn't need it.

[tmcw]

Same

[tristen]

It's calculated to derive the URL query. Given a url like:

/v4/directions/mapbox.driving/
-74.5597381591797,40.12139809056774;
-74.69306607374473,40.031006417727895;
-75.05781808872085,40.11136049688241;
-74.9486688115121,39.92301383728193;
-75.14762445604451,40.02994849538351.json?

It sorts the coordinates between the first(origin) + last(destination). If it's not sorted, the route is returned with the coordinates in the order that they were sent and not - as I could tell - sorted by the most optimized path.

[tmcw]

Yes, and the user inputs waypoints in order, and gets directions in order. This is a directions API, not a traveling-salesman API, and the assumption is that you would want to go to things in the order you type them, rather than an 'optimal' order - people do not plan, for example, roadtrips, based on algorithms.

[tristen]

Let me be a little more specific. Say I have a route planned with a single waypoint:

Origin = A
Waypoint = C
Destination = B

If I wanted to add another waypoint (D) before the first waypoint I, (as the user) would expect the route to order in this sequence: A -> D -> C -> B.

If I don't sort the order the sequence looks like this: A -> C -> D -> B. which is not the result I would expect.

[tmcw]

You create new waypoints when someone clicks a segment. You would check which segment they clicked to create the waypoint, and place the new waypoint in between its end points.

[tristen]

Ah that makes sense. I'm creating the directions route as a single LineString when it should be broken into segments.

[tristen]

💀 going to avoid doing anything weird with waypoint ordering all together.