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Dragoman

Move a map between Open Doctrines and Greater Diplomacy 5, in either direction, and get it back unchanged if you send it home again.

A dragoman was the interpreter attached to an embassy — the person through whom two powers who shared no language could still sign something.

pip install open-dragoman

dragoman convert 1914.odmap "base_maps/1914" --to gd5
dragoman convert "base_maps/GD4" gd4.odmap    --to odmap
dragoman roundtrip 1914.odmap                 # prove nothing was lost

Start here

Installing	pip install open-dragoman, a release binary, or from source
Getting Started	Convert your first map, and check the result
What Crosses	Which fields translate, which are computed, which ride along
Round Trips	What "lossless" means here, and what it does not
Scripts and Events	The two scripting systems, and where they meet
Languages	C, C++, Python, and anything else with an FFI
Diagnostics	Every message the converter can print, and what to do
Troubleshooting	When something did not work

What it is

The two games describe overlapping but unequal worlds. Open Doctrines models a province's population, its port, its ethnic minorities and its position on a political compass. Greater Diplomacy 5 models terrain, province adjacency, unit rosters, research and factions. Neither is missing anything it wants — they are different games — but a map crossing between them would be quietly poorer each way if nothing wrote the difference down.

Dragoman writes it down. Everything the destination cannot hold goes into a sidecar beside the map, which both games ignore and neither notices. So a one-way conversion is as faithful as the target format allows, and a return trip restores what the target could not hold.

It also fills in what the destination needs and the source never stored: province adjacency and centroids, a land/sea mask, sea provinces for a game that draws none, and research levels appropriate to the map's own date.

Status

Every map both games ship converts and comes home with nothing lost.

Suite	Result
Greater Diplomacy 5 maps (12 base + 16 scenarios)	28 / 28
Open Doctrines maps (5 scenarios + the world map)	6 / 6
Unit tests	5 / 5

Converted maps have been played in both games, not merely loaded: through GD5's own Controller and Map state with all 23 screens, and through OpenDoctrines --simulate for five AI turns. Most of what this library gets right, it gets right because somebody opened the result in the game and looked at it.

Two things it cannot do

• Treasuries. GD5 starts its nations with an empty stockpile; Open Doctrines expects a starting endowment. A GD5 map converted to Open Doctrines will bankrupt its world on the first turn until you set them. Reported as od.treasury.
• Research, going to Open Doctrines. A .odmap has nowhere to put it. See What Crosses.