Add German lakes example (#200)

docs/Project.toml

@@ -1,4 +1,5 @@
 [deps]
+Animations = "27a7e980-b3e6-11e9-2bcd-0b925532e340"
 ArchGDAL = "c9ce4bd3-c3d5-55b8-8973-c0e20141b8c3"
 CairoMakie = "13f3f980-e62b-5c42-98c6-ff1f3baf88f0"
 CoordinateTransformations = "150eb455-5306-5404-9cee-2592286d6298"

docs/make.jl

@@ -37,6 +37,7 @@ makedocs(;
             "Basic examples" => "examples/basic.md",
             "New API" => "examples/new.md",
             "Orthographic projection" => "examples/orthographic.md",
+            "German Lakes" => "examples/german_lakes.md",
             "Geostationary satellite image" => "examples/geostationary_image.md",
             "Contourf" => "examples/contourf.md",
             # "Multiple CRS" => "examples/multiple_crs.md",

examples/german_lakes.jl

@@ -0,0 +1,14 @@
+# # German lakes
+using GeoMakie, CairoMakie
+using GeoJSON, Downloads
+CairoMakie.activate!(px_per_unit = 4) # hide
+
+geoger = GeoJSON.read(read(Downloads.download("https://raw.githubusercontent.com/isellsoap/deutschlandGeoJSON/main/2_bundeslaender/4_niedrig.geo.json"), String))
+lakes = GeoJSON.read(read(Downloads.download("https://raw.githubusercontent.com/nvkelso/natural-earth-vector/master/geojson/ne_10m_lakes_europe.geojson"), String))
+
+fig = Figure()
+ga = GeoAxis(fig[1, 1]; dest = "+proj=merc", limits=((6, 15), (47, 55)))
+
+poly!(ga, geoger; strokewidth = 0.7, color=:gold, rasterize = 5)
+poly!(ga, lakes; strokewidth = 0.7, color=:blue, rasterize = 5,  xautolimits=false, yautolimits=false)
+fig

examples/is_it_a_plane.jl

@@ -0,0 +1,59 @@
+# # Geodesic paths - animation
+
+# Let's take the great circle flight path from New York (JFK) 
+# to Singapore (SIN) airport. 
+
+using GeoMakie, CairoMakie
+CairoMakie.activate!(px_per_unit = 2) # hide
+using Proj, Animations
+
+jfk = Point2f(-73.7789, 40.6397)
+sin = Point2f(103.9894, 1.3592)
+
+# First, we define the globe, as the WGS84 ellipsoid:
+geod = Proj.geod_geodesic(6378137, 1/298.257223563)
+# Then, we can solve the inverse geodesic problem, which provides 
+# the shortest path between two points on our defined ellipsoid:
+inv_line = Proj.geod_inverseline(geod, reverse(jfk)..., reverse(sin)...)
+# Just for reference, this is the path:
+f, a, p = lines(reverse(Proj.geod_path(geod, reverse(jfk)..., reverse(sin)...))...; linewidth = 3, axis = (; type = GeoAxis, dest = "+proj=natearth")); lines!(a, GeoMakie.coastlines(), color = (:black, 0.4)); f
+
+# We'll use a satellite view for this, and alter the projection as a way of controlling the animation.
+
+# First, we'll create 2 observables which control the position of the "camera":
+# distance along path (from 0 to 1) and altitude (in meters)!
+
+# The projection will always be centered at wherever the plane is.
+
+# We first 
+
+times = [0, 0.5, 17.5, 18]
+distances = [0, 0.05, 0.95, 1]
+altitudes = [357860, 35786000/2, 35786000/2, 357860]
+distance_animation = Animation(times, distances, linear())
+altitude_animation = Animation(times, altitudes, sineio())
+
+
+# In order to investigate this kind of projection, you can create 
+# a GeoAxis with the projection you want, and then change the
+# altitude to see how the zoom works in real time!
+@time begin
+fig = Figure()
+sl = Slider(fig[2, 1], range = exp.(LinRange(log(357860), log(35786000), 30)), startvalue = 35786000)
+satview_projection = lift(sl.value) do alt
+    "+proj=geos +h=$(round(Int, alt)) +lon_0=$(sin[1]) +lat_0=$(sin[2])"
+end
+ga = GeoAxis(fig[1, 1]; dest = satview_projection)
+meshimage!(ga, -180..180, -90..90, GeoMakie.earth(), shading = NoShading)
+fig
+end
+
+record(fig, "plots/plane.mp4", LinRange(0, 1, 120)) do i
+    satview_projection[] = "+proj=geos +h=$(round(Int, at(altitude_animation, i*18))) +lon_0=$(Proj.geod_position_relative(inv_line, i)[2]) +lat_0=$(Proj.geod_position_relative(inv_line, i)[1])"
+    yield()
+end
+
+fig = Figure()
+ga = GeoAxis(fig[1, 1]; dest = "+proj=nsper +h=3000000 +lat_0=-20 +lon_0=145")
+meshimage!(ga, -180..180, -90..90, GeoMakie.earth(), shading = NoShading)
+fig