realwallpaper: add version with star constellations

krebs/5pkgs/simple/realwallpaper/default.nix

@@ -271,6 +271,32 @@ pkgs.writers.writeDashBin "generate-wallpaper" ''
         shade=15
       ''}
 
+    ${pkgs.writers.writePython3 "get_constellations" {
+      libraries = [ pkgs.python3Packages.astropy ];
+    } ./get_constellations.py} ${pkgs.fetchurl {
+      url = "https://raw.githubusercontent.com/ofrohn/d3-celestial/d2e20e104b86429d90ac8227a5b021262b45d75a/data/constellations.lines.json";
+      sha256 = "0g71fdrnxvxd6pcqvihj2q9iaynrl7px45kzw6qm1kymynz6ckr9";
+    }} > constellations.arcs
+
+    xplanet --num_times 1 --geometry $xplanet_out_size \
+      --output xplanet-krebs-stars-output.png --projection merc \
+      -config ${pkgs.writeText "xplanet-krebs-stars.config" ''
+        [default]
+
+        arc_thickness=1
+        arc_file=constellations.arcs
+
+        [earth]
+        "Earth"
+        map=daymap-final.png
+        night_map=nightmap-final.png
+        cloud_map=clouds.png
+        cloud_threshold=1
+        cloud_gamma=10
+        marker_file=marker_file
+        shade=15
+      ''}
+
     # trim xplanet output
     if needs_rebuild realwallpaper.png xplanet-output.png; then
       convert xplanet-output.png -crop $out_geometry \
@@ -278,7 +304,6 @@ pkgs.writers.writeDashBin "generate-wallpaper" ''
         mv realwallpaper-tmp.png realwallpaper.png
     fi
 
-    # trim xplanet output
     if needs_rebuild realwallpaper-marker.png xplanet-marker-output.png; then
       convert xplanet-marker-output.png -crop $out_geometry \
         realwallpaper-marker-tmp.png
@@ -292,6 +317,12 @@ pkgs.writers.writeDashBin "generate-wallpaper" ''
         mkdir -p archive
         convert realwallpaper-krebs.png archive/"$(date -Is)".jpg
     fi
+
+    if needs_rebuild realwallpaper-krebs-stars.png xplanet-krebs-stars-output.png; then
+      convert xplanet-krebs-stars-output.png -crop $out_geometry \
+        realwallpaper-krebs-stars-tmp.png
+        mv realwallpaper-krebs-stars-tmp.png realwallpaper-krebs-stars.png
+    fi
   }
 
   main "$@"

krebs/5pkgs/simple/realwallpaper/get_constellations.py

@@ -0,0 +1,36 @@
+from astropy.coordinates import SkyCoord, ITRS, representation
+from astropy.time import Time
+import json
+import sys
+
+
+def convert_to_itrs(coord):
+    c = SkyCoord(coord[0], coord[1], unit='degree', frame='icrs')
+    c_itrs = c.transform_to(ITRS(obstime=Time.now()))
+    rep = c_itrs.represent_as(representation.UnitSphericalRepresentation)
+    return [rep.lat.deg, rep.lon.deg]
+
+
+def points_to_lines(points):
+    lines = []
+    for x in range(len(points) - 1):
+        lines.append([points[x], points[x+1]])
+    return lines
+
+
+with open(sys.argv[1]) as f:
+    constellations = json.load(f)['features']
+
+output = []
+
+for const in constellations:
+    for line in const['geometry']['coordinates']:
+        transformed_line = []
+        for point in line:
+            transformed_line.append(convert_to_itrs(point))
+
+        line_combined = points_to_lines(transformed_line)
+        for l in line_combined:  # noqa
+            output.append(f'{l[0][0]} {l[0][1]} {l[1][0]} {l[1][1]} # {const["id"]}')  # noqa
+
+print('\n'.join(output))