Implement fading for features that hit minzoom/maxzoom limits
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- Dominant language
- TypeScript
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Description
The isHidden() method of StyleLayer prevents us from drawing any layer that's outside its min/maxzoom limits (or has its visibility toggled to 'none'). Now that we're doing explicit time-based fade animations, it should be possible for us to animate these transitions -- we just need to (1) make sure the min/maxzoom calculation is fed into collision detection, and (2) update the drawing code to keep drawing any layers in the middle of fading (assuming this is a significant savings over just drawing the layer with nothing in it).
I noticed this while zooming in on a city label: at z14 in streets v10, place-city-label-lg will disappear abruptly. It doesn't look that bad, but it'd still be a nice improvement to fade it.
/cc @ansis @nickidlugash @jfirebaugh
Contributor guide
First steps
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- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with StyleLayer.isHidden() and trace how min/maxzoom limits reach collision detection and the drawing code. Check the city-label case described for place-city-label-lg at z14; done means layers crossing zoom limits fade smoothly while visibility changes still work.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- computer-graphics, frontend
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100