Render MVTLayer using TextLayer

Description

I’ve been using MVTLayer with the default renderSubLayers and it works perfectly. Aside that, I’ve created a layer that extends from CompositeLayer to show a TextLayer above the GeoJsonLayer following this deck.gl tutorial. It works but it repeats the TextLayer inside each geometry.

Repro Steps

I’ve made an example that reproduces the problem.

As you can see in this screenshot, the word Illinois is repeated four times inside the state polygon.

Environment

• Framework Version: deck.gl 8.1.1
• Browser Version: Chrome 80.0.3987.163
• OS: macOS 10.14.6

[kylebarron]

Are you saying is posible to subclass MVTLayer to create an “adaptor layer”

Yes, I think the icon-cluster-layer is actually a good reference point. You’ll have to play around with it a bit. For example you can see that the MVTLayer currently subclasses the TileLayer I believe. So you might have to copy some code from the MVTLayer so that you can render both geometry layers and a TextLayer.

Along the same lines, a Text/Symbol layer that handles symbol collisions is of interest to me personally. It might be out of scope for the main Deck.gl repository, since Deck.gl isn’t in the game of creating a basemap, but it could be a separate open source repo. I’ve started reading through relevant code in Mapbox GL JS, but haven’t gotten around to extracting it for an implementation that might work with Deck.gl.

Polygon data will still be split into multiple tiles, so can we merge them back at the client-side to find the anchor point of the labels or should we change the part that does the MVT generation ?

Currently there’s no merging that happens in the MVTLayer client side. This would be non-trivial since the number of tiles necessary to merge a polygon is unknown before retrieving the tiles.

Personally, I think you’d have much better luck pre-generating anchor points for text labels and storing them as a point layer in the MVT, so that you aren’t finding points client side.

I think previous versions of the MVTLayer did this client-side polygon merging but stopped it because it was not the best alternative, so it is okay to do it here ?

I don’t think polygon merging was ever implemented, but it was discussed here: https://github.com/uber/deck.gl/pull/3704#issuecomment-535613783

[juandjara]

Hello, I’m interested in this too. Are you saying is posible to subclass MVTLayer to create an “adaptor layer” like in the icon-cluster example or the labeled-geosjon example ??

Polygon data will still be split into multiple tiles, so can we merge them back at the client-side to find the anchor point of the labels or should we change the part that does the MVT generation ?

I think previous versions of the MVTLayer did this client-side polygon merging but stopped it because it was not the best alternative, so it is okay to do it here ?