mapbox/mapbox-gl-js

Symbol interpolation issue when icon-pitch-alignment is "map"

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#8,110 opened on Apr 2, 2019

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bug :lady_beetle:good first issue

Description

mapbox-gl-js version: v0.54.0-beta.1

browser: any

Steps to Trigger Behavior

  1. create a symbol layer with icon-pitch-alignment set to "map"
  2. do not rotate or pitch the map

Expected Behavior

Icon should be rendered with NEAREST interpolation

Actual Behavior

Icon is rendered with LINEAR interpolation

Hint: there is a condition in draw_symbol.js:197

pitchWithMap || tr.pitch !== 0

I think it should be just

tr.pitch !== 0

because when icon-pitch-alignment is set to "map", and neither the icon nor the map is rotated, NEAREST should be used. (same as "viewport" alignment)

Contributor guide

Tech stack
javascript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScriptmapbox gl js symbol layers
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85
Research direction
The bug is in draw symbol.js at line 197, where the condition `pitchWithMap || tr.pitch !== 0` should be changed to `tr.pitch !== 0`. This ensures NEAREST interpolation is used when icon pitch alignment is 'map' and the map is not pitched. The issue has no linked pull requests, so the fix is straightforward and well documented. Review the symbol rendering code in draw symbol.js to implement the change and verify with a test case.
Symbol interpolation issue when icon-pitch-alignment is "map" · mapbox/mapbox-gl-js#8110 | Good First Issue