libgeo-utils-cpp

Practical latitude/longitude geometry for C++17 projects that need GPS math, not a full geometry framework.

Distance, heading, polygon area, point-in-polygon, and path proximity checks — header-only, no dependencies, no build step.

The API is inspired by Google Maps geometry utilities and uses the same spherical Earth approximation model.

Features

• Lat/lng-native API — pass latitude/longitude coordinates directly, no framework-specific point types to convert through.
• Header-only, dependency-free — about 50 KB across 8 headers; nothing to build or link.
• Spherical math — distance, heading, offset, interpolation, area.
• Polygon utilities — point-in-polygon, path proximity, snap-to-route (closest_point_on_path), Douglas–Peucker simplification, and LatLngBounds viewport math.
• Polyline encoding — encode/decode for the Google Encoded Polyline format, including the polyline6 grid used by OSRM/Valhalla/Mapbox.
• Fast — matches hand-written haversine on distance; especially strong on polygon area (see benchmarks).
• Focused scope — intentionally small API for GPS, navigation, tracking, backend, and GIS workflows.