Enum RiverThreshold 

pub enum RiverThreshold {
    Density(f32),
    MinUpstreamCells(f32),
    PerEdge(f32),
}

How the river network is cut out of the flow accumulation map.

Which one to use:

• Density asks for an area share — “about 1% of the land should be river”. It adapts to any terrain, but it does not transfer between map sizes: catchments grow with area while channels grow with length, so the same share yields a visually denser network on a small map than on a large one. Good for one-off renders.
• MinUpstreamCells is absolute — “a channel starts once 500 cells drain through”. Physically meaningful and comparable across maps of the same cell size, so it is the right choice when cells have a fixed real-world size (a game world tiled from several maps).
• PerEdge scales the absolute threshold with the map edge, i.e. required upstream cells = factor * max(width, height). Use it when a map always represents “one island”, whatever its resolution, and you want the same-looking network at every resolution.

Variants

Density(f32)

Approximate fraction of land cells covered by rivers, in [0, 1].

MinUpstreamCells(f32)

Minimum upstream catchment, in cells, for a cell to be a river.

PerEdge(f32)

Minimum upstream catchment as a multiple of the longer map edge.

Trait Implementations

impl Clone for RiverThreshold

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for RiverThreshold

impl Debug for RiverThreshold

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for RiverThreshold

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for RiverThreshold