Basemap

[dabreegster]

There's currently no map displayed underneath all the bus data:

We need one just to be able to orient. Many options for how we pull this off...

• use one from A/B Street
  • the styling is likely to clash with whatever we want to display on top
  • all the zoomed-in detail is irrelevant
  • extra perf / file size hit
  • the most important things (road labels) aren't even great
• piggyback on mapbox
  • web-only
  • The existing piggyback demo wouldn't be appropriate. No mapbox controls at all should be used; we want widgetry to "own" basically everything
  • maybe we just separately initialize mapbox, hand it our webgl context (or use the one it provides), disable all interactions, and forcibly change its viewport all the time
• something new to display raster tiles
  • web and native
  • would have to implement new widgetry tricks (for textures, possibly memory management thereof)
  • could probably cache just the tiles we need from somewhere
• something new to display vector tiles?

[dabreegster]

https://user-images.githubusercontent.com/1664407/174091260-ef41a1e0-b17c-42fc-9459-3a8449dcb2ba.mp4

The "inverse piggyback" mostly works. We have two WebGL contexts on top of each other. Mapbox has all interactions disabled. When the canvas moves in the widgetry app, we just force the mapbox camera to re-sync. It's jittery, but works!

@dingaaling We should explore this trick for the LTN tool. If it'd be useful for the basemap to be a satellite layer or regular Mapbox styling, we can just choose what LTN-specific styling / controls to draw on top.

[dabreegster]

MVP now merged. Still need to figure out why Mapbox updating is jittery, and probably have a way to lower the opacity of the stuff the app draws, to actually see the roads underneath.