make altitudes reusable using GroundAltitude model

src/c3nav/mapdata/models/__init__.py

@@ -1,5 +1,6 @@
 from c3nav.mapdata.models.update import MapUpdate  # noqa
 from c3nav.mapdata.models.access import AccessRestriction  # noqa
+from c3nav.mapdata.models.altitudes import GroundAltitude  # noqa
 from c3nav.mapdata.models.level import Level  # noqa
 from c3nav.mapdata.models.geometry.level import Building, Space, Door, AltitudeArea  # noqa
 from c3nav.mapdata.models.geometry.space import Area, Stair, Obstacle, LineObstacle, Hole, AltitudeMarker  # noqa

src/c3nav/mapdata/models/altitudes.py

@@ -0,0 +1,19 @@
+from django.db import models
+from django.utils.translation import gettext_lazy as _
+
+
+class GroundAltitude(models.Model):
+    """
+    A pre-defined ground altitude
+    """
+    name = models.CharField(_('Name'), unique=True, max_length=70)  # a slugfield would forbid periods
+    altitude = models.DecimalField(_('altitude'), null=False, max_digits=6, decimal_places=2)
+
+    class Meta:
+        verbose_name = _('Ground Altitude')
+        verbose_name_plural = _('Ground altitudes')
+        default_related_name = "groundaltitudes"
+
+    @property
+    def title(self):
+        return f'{self.name} ({self.altitude}m)'

src/c3nav/mapdata/models/geometry/level.py

@@ -218,7 +218,8 @@ class AltitudeArea(LevelGeometryMixin, models.Model):
         spaces = {}
         levels = Level.objects.prefetch_related('buildings', 'doors', 'spaces', 'spaces__columns',
                                                 'spaces__obstacles', 'spaces__lineobstacles', 'spaces__holes',
-                                                'spaces__stairs', 'spaces__ramps', 'spaces__altitudemarkers')
+                                                'spaces__stairs', 'spaces__ramps',
+                                                'spaces__altitudemarkers__groundaltitude')
         logger = logging.getLogger('c3nav')
 
         for level in levels:
@@ -285,7 +286,7 @@ class AltitudeArea(LevelGeometryMixin, models.Model):
 
             # give altitudes to areas
             for space in level.spaces.all():
-                for altitudemarker in space.altitudemarkers.all():
+                for altitudemarker in space.altitudemarkers.select_related('groundaltitude').all():
                     for area in space_areas[space.pk]:
                         if area.geometry_prep.contains(unwrap_geom(altitudemarker.geometry)):
                             area.altitude = altitudemarker.altitude

src/c3nav/mapdata/models/geometry/space.py

@@ -298,16 +298,21 @@ class AltitudeMarker(SpaceGeometryMixin, models.Model):
     An altitude marker
     """
     geometry = GeometryField('point')
-    altitude = models.DecimalField(_('altitude'), null=False, max_digits=6, decimal_places=2)
+    groundaltitude = models.ForeignKey('mapdata.GroundAltitude', on_delete=models.CASCADE,
+                                       verbose_name=_('altitude'))
 
     class Meta:
         verbose_name = _('Altitude Marker')
         verbose_name_plural = _('Altitude Markers')
         default_related_name = 'altitudemarkers'
 
+    @property
+    def altitude(self) -> Decimal:
+        return self.groundaltitude.altitude
+
     @property
     def title(self):
-        return '%s (%sm)' % (super().title, self.altitude)
+        return f'#{self.pk}: {self.groundaltitude.title}'
 
 
 class LeaveDescription(SerializableMixin):