EdgeWeightGPS
Cyberpunk 2077 RED4ext plugin that improves player GPS routing by penalizing short-segment churn in the native GPS solver. The current validated default pushes the GPS toward smoother, higher-momentum driving corridors without globally forcing every route onto highways.
Current Status
Working prototype, validated in-game.
- Route scoring patch: enabled.
- Live tuning file: enabled.
- Current default fixed-edge penalty:
80.0. - Highway multiplier: neutral
1.0; the earlier highway-speed/class experiments are not part of the playable default.
The active package is a RED4ext plugin only:
red4ext/plugins/EdgeWeightGPS/EdgeWeightGPS.dll
red4ext/plugins/EdgeWeightGPS/momentum_weights.bin
red4ext/plugins/EdgeWeightGPS/solver_weights.bin
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 the 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 nonnegative 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.
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 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/EdgeWeightGPS-mingw64/EdgeWeightGPS.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, installs it into the Flatpak Steam Cyberpunk 2077 folder, and writes the validated defaults:
momentum_weights.bin = 80.0solver_weights.bin = 1.0
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.
Live Tuning
momentum_weights.bin is a single little-endian float32 and is hot-reloaded
every 500 ms while the game is running.
Useful presets:
python3 tools/write_momentum_weights.py vanilla # 0.0
python3 tools/write_momentum_weights.py default # 80.0
python3 tools/write_momentum_weights.py overstrong # 160.0, known too high
solver_weights.bin is still present for older highway multiplier experiments,
but the playable default keeps it neutral:
python3 tools/write_solver_weights.py vanilla # 1.0
Repository Notes
This repository also contains older experiments and reverse-engineering tools:
- REDmod/archive traffic resource patchers.
- Traffic lane and connection probability patchers.
- Static disassembly helpers.
- RED4ext logging probes.
Those tools 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: