"geometry clipping" of data sources

[meetar]

Would it be possible to allow datasources to be "clipped" by a shape or boundary? Eg: to allow a user to use one datasource inside a given boundary and another datasource outside of it.

I imagine this would most commonly look like: custom/proprietary data inside a boundary, and our OSM-derived vector tiles outside of it.

[bcamper]

I think a simple version of what you are describing is implemented in this branch:

https://github.com/tangrams/tangram/compare/fallback-source

The idea here was that a given data source might only have partial tile coverage, and when it hit a 404, it would fallback to another data source (probably the canonical Mapzen one).

We had an inquiry from a potential user about this, so I tried that out as an experiment. It's viable and the logic is simple, but was waiting for further discussion around use cases before adding to a release. My inclination would be do something simple/coarse like this (one could apply a source bounds to clip, for instance) rather than supporting something like an arbitrary polygon clip (which would add considerable complexity vs. piggybacking on something we have).