Function route 

pub fn route(
    size: usize,
    terrain: &HeightGrid<'_>,
    floors: &Floors,
    pathfinder: &mut Pathfinder,
    river: &[[f32; 2]],
    dock: [f32; 3],
    dock_yaw: f32,
) -> (Vec<[f32; 3]>, f32)

The river’s points before it enters the map, a water path (mode 3, types 7..9) from where it enters to the dock and on to where it leaves, then the river’s points after the first one off the map again. Also the dock heading, turned with the river’s flow at the route point nearest the dock.

Original: FUN_140046040 (route).