Give the stars large id numbers.

Then when you display them they can be mapped to a deterministic human
readable format, like letters or some Unicode symbols? Name generators?

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stars.py

@@ -17,7 +17,22 @@
 #    You should have received a copy of the GNU General Public License
 #    along with game.  If not see <http://www.gnu.org/licenses/>.
 #
-from random import randint, expovariate, seed
+'''
+A field of stars.  Each has planets.  Each planet has...?
+
+Keep it simple.
+
+Stars have what qualities?
+- Cosmetic
+  - color
+  - brightness
+  - size
+- Game stats
+  - ?
+
+
+'''
+from random import randint, expovariate, seed, getrandbits
 from poisson import poisson
 
 
@@ -30,21 +45,38 @@ MINIMUM_DISTANCE_BETWEEN_STARS = 160
 WIDTH, HEIGHT = 10240, 7680
 
 
+# Database stuff.  SQL, etc.
+
+def generate_list_of_u64_for_ids(n):
+    '''
+    Return a sorted list of n random 64-bit integers
+    (suitable for SQLite rowid columns.)
+    See https://www.sqlite.org/lang_createtable.html#rowid
+    '''
+    result = set()
+    safety = 10
+    while n > 0:
+        canidate = getrandbits(63)
+        while canidate in result:
+            if not safety:
+                raise RuntimeError('this should not happen')
+            safety -= 1
+            canidate = getrandbits(63)
+        result.add(canidate)
+        n -= 1
+    return sorted(result)
+
+
 TABLES = [
-    'create table stars (x INTEGER, y INTEGER, radius INTEGER)',
+    'create table stars (id INTEGER PRIMARY KEY, x INTEGER, y INTEGER, radius INTEGER)',
     ]
 
 
-def generate_stars(width, height, minimum_distance_between_stars):
-    for x, y in poisson(width, height, minimum_distance_between_stars):
-        yield x, y, round(1 + expovariate(1))
-
-
 def init_db(conn):
     print('Generating star data.')
     c = conn.cursor()
     for values in generate_stars(WIDTH, HEIGHT, MINIMUM_DISTANCE_BETWEEN_STARS):
-        c.execute('insert into stars values (?, ?, ?)', values)
+        c.execute('insert into stars values (?, ?, ?, ?)', values)
     c.close()
     conn.commit()
 
@@ -54,3 +86,24 @@ def iter_stars(conn):
     c.execute('select x, y, radius from stars')
     yield from c.fetchall()
     c.close()
+
+
+# Procedural Generation of solar system data
+
+
+def generate_stars(width, height, minimum_distance_between_stars):
+    # we could just call getrandbits(64) here for ID and hope for the best.
+    # it's a large domain (u64) so collisions are unlikely(!).
+    coords = list(poisson(width, height, minimum_distance_between_stars))
+    ids = generate_list_of_u64_for_ids(len(coords))
+    for star_id, (x, y) in zip(ids, coords):
+        yield star_id, x, y, round(1 + expovariate(1))
+
+
+def how_many_planets():
+    n = round(gauss(5, 5))
+    while n < 0:
+        n = round(gauss(5, 5))
+    return n
+
+