SDF text rendering plugin

[maxammann]

video.webm

TODO:

• Basic text collision
• Draw text along lines
• Custom source property - Add configurable text-field property for symbol layers #326
• Dynamically loading protobufs
• Caching protobufs
• Unloading protobufs from GPU
• Avoid overdrawing from labels of neithboring tiles

Q:

• How many glaph textures do we want to have? One per tile? One per protobuf?
• Where to cache data? Render thread/worker thread?
  • Likely render thread so we can share data between threads
  • Mabye BG if the requests cache

The basic implmenetation for SDFs is based on https://github.com/stadiamaps/maps-rs (licensed as MIT OR APACHE)

[kylerchin]

LETS GOOOOOO

[michaelkirk]

Cool. Just a drive by review, my first peep at maplibre-rs code.

[maxammann]

Language	Lines	Code	Done
layout/circle_layout.hpp	164	120	❌
layout/clip_lines.cpp	81	68	❌
layout/clip_lines.hpp	14	10	❌
layout/layout.hpp	43	33	🚧
layout/merge_lines.cpp	92	67	❌
layout/merge_lines.hpp	30	21	❌
layout/pattern_layout.hpp	210	183	❌
layout/symbol_feature.hpp	37	29	✅
layout/symbol_instance.cpp	222	189	✅
layout/symbol_instance.hpp	132	115	✅
layout/symbol_layout.cpp	1193	1000	🚧
layout/symbol_layout.hpp	145	104	✅
layout/symbol_projection.cpp	532	377	🚧
layout/symbol_projection.hpp	77	65	🚧
text/bidi.hpp	43	25	✅ without ICU
text/check_max_angle.cpp	83	54	❌
text/check_max_angle.hpp	12	7	❌
text/collision_feature.cpp	171	111	✅
text/collision_feature.hpp	163	128	✅
text/collision_index.cpp	467	357	✅
text/collision_index.hpp	120	97	✅
text/cross_tile_symbol_index.cpp	269	207	❌
text/cross_tile_symbol_index.hpp	84	66	❌
text/get_anchors.cpp	177	119	❌
text/get_anchors.hpp	29	24	❌
text/glyph_atlas.cpp	48	34	🚧
text/glyph_atlas.hpp	25	17	🚧
text/glyph_manager_observer.hpp	19	13	❌
text/glyph_manager.cpp	176	137	❌
text/glyph_manager.hpp	79	53	❌
text/glyph_pbf.cpp	96	73	❌
text/glyph_pbf.hpp	13	8	❌
text/glyph_range.hpp	26	17	✅
text/glyph.cpp	14	10	✅ (missing AlphaImage)
text/glyph.hpp	135	108	✅ (missing AlphaImage)
text/language_tag.cpp	214	102	❌
text/language_tag.hpp	46	16	❌
text/local_glyph_rasterizer.hpp	47	14	❌
text/placement.cpp	1652	1356	❌
text/placement.hpp	211	163	❌
text/quads.cpp	336	259	✅
text/quads.hpp	72	62	✅
text/shaping.cpp	594	486	✅
text/shaping.hpp	100	79	✅
text/tagged_string.cpp	83	67	✅
text/tagged_string.hpp	101	58	✅

others:

• i18n
• utils
• font_stack
• image_atlas
• feature_index
• image
• image_impl
• geometry_tile_data

[kylerchin]

When will this be merged?

[maxammann]

On time for Christmas 🤞

[maxammann]

@michael-markl pls review

[birkskyum]

This PR appear to be working as expected, is anything holding it from review?

[maxammann]

@birkskyum appreciate you taking over here :) i think it makes a lot sense though to create a separate PR here. I don't know what my local state is and force pushing on a shared branch is problematic 😅

[birkskyum]

Screen.Recording.2026-02-19.at.00.33.09.mov

Seems like a good addition, where the additional TODOs can come in increments.