Document legends export format (or: how do river paths work?)

[Lancelotbronner]

Rivers paths have "coordinates" with 5 components and I'm not sure what they mean?

<path>4,123,85,5,100|3,123,164,2,99|2,123,241,8,99|</path>
<end_pos>1,123</end_pos>

This test world is 129x129 so I'm not sure what the middle number means, could it be flow/size? If that's the case I'm guessing the path could be a straight line from eg. 4,123 to 5,100 but that doesn't seem to check out with the world map.

My other guess is that only the first 2 components are the coordinates and the other three are something else entirely, I'm hoping one of those can help determine the size.

I'm trying to determine the list of coordinates on which this river flows. Also is there a way to determine the size (large, medium, small, brook) of the river?

Context: I'm building another LegendsViewer equivalent but plan on using Dwarf Fortress assets to render it as close as possible to what we see in-game.

[myk002]

There is some discussion on this topic here: https://discord.com/channels/793331351645323264/807444515194798090/1132838980942057532

If you're not already on the Discord server, the join link is https://dfhack.org/discord

[Lancelotbronner]

Thanks! I just joined the Discord server but I don't have access to the #feature-discuss channel.

[myk002]

(following up on Discord)

[lethosor]

For posterity: the code is here: https://github.com/DFHack/scripts/blob/542d4089fc907a151e7b4fc0b75c95dd3dbef31c/exportlegends.lua#L206-L219

relevant bits from the Discord discussion:

so the source confirms that it is indeed x, y, flow, exit_tile, elevation

Wait so <path>6,2,0,10,99 | 7,2,75,8,99 | 7,1,141,13,99 |</path> would be a river of only 3 tiles? I don't understand

no, of three segments

More information in df-structures: https://github.com/DFHack/df-structures/blob/ffdf5771ea23e3b35f5f46624f773a555e1c450f/df.world-data.xml#L246-L272