mercator

Mercator is a Typst plugin to render GeoJSON and TopoJSON as SVG maps.

usage

#import "@preview/mercator:0.1.2": *

#let world = read("examples/data/world.json", encoding: none)

#render-map(world, (
  projection: (
    type: "orthographic",
    center_lat: 45,
    center_lon: 10,
  ),
  graticule: (step: 15),
), width: 100%)

documentation

Check examples/documentation.pdf, it covers all the features with examples.

config options

Option	Type	Default	Description
stroke	string	"black"	Stroke color. Supports {property_name} interpolation.
stroke_width	float	0.05	Stroke width
fill	string	"white"	Fill color. Supports {property_name} interpolation.
fill_opacity	float	1.0	Fill opacity
fill_pattern	string	none	"hatched", "crosshatched", or "dotted". Supports {property_name}.
point_radius	float	stroke_width * 5	Radius for Point/MultiPoint geometries
point_color	string	same as fill	Point fill color. "none" hides points. Supports {property_name}.
viewbox	array	auto	Manual viewbox as (x, y, width, height)
viewbox_padding	float	0.15	Padding fraction around auto-computed viewbox
label	string or array	none	Label template: "{name}" or array of {text, font_size, color, font_family} objects
label_color	string	"black"	Default label color
label_font_size	float	0.3	Default label font size
label_font_family	string	"Arial"	Default label font family
projection	object	equirectangular	Projection config (see below)
graticule	object	none	Graticule overlay config (see below)
tissot	object	none	Tissot's indicatrix overlay config (see below)

projections

Type	Category	Parameters
equirectangular	Cylindrical	central_meridian
mercator	Cylindrical	central_meridian
cassini	Cylindrical	central_meridian
lambert_conformal_conic	Conic	standard_parallel_1, standard_parallel_2, central_meridian, latitude_of_origin
albers_equal_area	Conic	standard_parallel_1, standard_parallel_2, central_meridian, latitude_of_origin
bonne	Pseudo-conic	standard_parallel, central_meridian
polyconic	Pseudo-conic	central_meridian
robinson	Pseudo-cylindrical	central_meridian
natural_earth	Pseudo-cylindrical	central_meridian
hammer	Pseudo-cylindrical	central_meridian
winkel_tripel	Pseudo-cylindrical	central_meridian
orthographic	Azimuthal	center_lat, center_lon
gnomonic	Azimuthal	center_lat, center_lon
lambert_azimuthal_equal_area	Azimuthal	center_lat, center_lon
azimuthal_equidistant	Azimuthal	center_lat, center_lon
wiechel	Pseudo-azimuthal	center_lat, center_lon
peirce_quincuncial	Other	center_lon
authagraph	Other	(no parameters)

graticule

Option	Type	Default	Description
step	float	15.0	Degrees between grid lines
color	string	"#ccc"	Line color
width	float	0.5	Line width
opacity	float	0.6	Line opacity

tissot

Option	Type	Default	Description
step	float	30.0	Degrees between indicator circles
radius	float	5.0	Circle radius in degrees
fill	string	"red"	Fill color
fill_opacity	float	0.3	Fill opacity
stroke	string	"red"	Stroke color
stroke_width	float	0.5	Stroke width
max_lat	float	60.0	Maximum latitude for indicators

build locally

cargo build --target wasm32-unknown-unknown --release
wasm-opt -O4 --enable-bulk-memory --strip-debug \
  target/wasm32-unknown-unknown/release/mercator.wasm -o mercator/mercator.wasm

NB: wasm-opt is part of binaryen.