Rhumb lines layer — viz_rhumbs • geovizr

The viz_rhumbs function draws rhumb lines (loxodromes), similar to those found on old portolan charts. These lines represent paths of constant bearing.

Usage

viz_rhumbs(
  map,
  id = NULL,
  nb = 16,
  pos = c(10, 10),
  coords = "svg",
  stroke = "#394a70",
  strokeWidth = 1,
  strokeOpacity = 0.3,
  strokeDasharray = c(3, 2),
  ...
)

Arguments

map: A geovizr map object created using viz_create().
id: character. Optional. Unique layer id.
nb: numeric. Optional. Number of lines (default 16).
pos: numeric vector. Optional. Position of the lines (default c(10, 10)). If coords = "svg", values are in SVG coordinates. If coords = "geo", values are longitude and latitude.
coords: character. Optional. Coordinate system for pos (default "svg"). If coords = "geo" and the map is zoomable, lines follow zoom interactions.
stroke: character. Optional. Stroke color (default "#394a70").
strokeWidth: numeric. Optional. Stroke width (default 1).
strokeOpacity: numeric. Optional. Stroke opacity (default 0.3).
strokeDasharray: numeric or vector. Optional. Stroke dash pattern (default c(3, 2)).
...: Additional SVG attributes (e.g. opacity, strokeLinecap, etc.).

Value

A modified `geoviz` map object with a new layer added. Rendering is performed using viz_render().

Examples

library(sf)
world <- st_read(
  system.file("gpkg/world.gpkg", package = "geovizr"),
  quiet = TRUE
)

viz_create(projection = "EqualEarth", background = "white") |>
  viz_path(datum = world, fill = "#f1f3f5") |>
  viz_rhumbs(
    nb = 32, coords = "geo", pos = c(0, 0),
    fill = "#38896F"
  ) |>
  viz_render()