MomentumGPS

Cyberpunk 2077 RED4ext plugin that improves player GPS routing by penalizing short-segment churn in the native GPS solver. The validated default pushes the GPS toward smoother, higher-momentum driving corridors without globally forcing every route onto highways.

Current Status

Working RED4ext plugin, validated in-game.

Route scoring patch: enabled.
Current fixed ordinary-edge penalty: 80.0.
Live tuning: removed from the release build.
Highway multiplier/class weighting experiments: not part of the playable default.

The active package is a RED4ext plugin only:

red4ext/plugins/MomentumGPS/MomentumGPS.dll
red4ext/plugins/MomentumGPS/README.txt

What It Patches

Reverse engineering found the player GPS route search loop around the native solver relaxation cluster. The useful patch surface is not the script-facing RunGPSQuery/UpdateGPSQuery helpers and not generated traffic maxSpeed fields. The playable hook patches the two ordinary adjacency expansion sites feeding the native relax/update routine at 0x40ba58.

The plugin adds a fixed cost to ordinary edge expansion. In practice, this makes many tiny street segments and repeated 90-degree stair-steps less attractive, while still allowing local roads when they are the right path.

This is an inline native patch against tested Cyberpunk 2077 executable RVAs. A future game update may require fresh verification.

Validation Summary

The default 80.0 penalty was selected after live A/B testing:

0.0: vanilla behavior; visibly stair-stepped in highlighted routes.
40.0: partial improvement, but still missed useful smoother corridors.
80.0: best observed result; selected smoother high-speed corridors and passed drive testing.
160.0: too high; caused bad hairpins/local access and one fallback-style route.

Drive validation at 80.0:

The Dogtown route used a smoother highway corridor and drove cleanly at high speed.
Live minimap recalculation still worked after a deliberate detour.
Claire/Westbrook route also drove cleanly; one blind hill/ramp surprise was driver unfamiliarity, not a route failure.

See contrib/re/docs/gps-momentum-field-tests.md for the detailed test notes, screenshots, and log references.

Build

Build in the Fedora toolbox:

toolbox run -c 2077 ./tools/build_red4ext_shim.sh

This writes:

build/red4ext/MomentumGPS-mingw64/MomentumGPS.dll

Install Locally

Only install while the game is cold.

toolbox run -c 2077 ./tools/install_red4ext_shim.sh

The install script builds the DLL and installs it into the Flatpak Steam Cyberpunk 2077 folder. Override the game directory with CYBERPUNK2077_GAME_DIR if needed.

Package

Create a redistributable RED4ext zip:

toolbox run -c 2077 ./tools/package_red4ext_mod.sh

The package is written under dist/ and contains the red4ext/ folder layout expected by the game.

Repository Notes

Older experiments, logs, screenshots, extracted work data, and reverse-engineering tools live under contrib/re:

REDmod/archive traffic resource patchers.
Traffic lane and connection probability patchers.
Static disassembly helpers.
RED4ext logging probes.
Earlier live-tuning helpers and presets.

Those files are retained because they explain the route-finding system and document failed approaches, but they are not part of the current playable package. The important debriefs are:

3.7 KiB Raw Blame History