Add opposing points: DESC, MC, ANTIVERTEX

Solves #4

src/gswe-moment.c

@@ -805,14 +805,39 @@ gswe_moment_calculate_house_positions(GsweMoment *moment, GError **err)
                 err
             );
     }
+    if (gswe_moment_has_planet(moment, GSWE_PLANET_DESCENDANT)) {
+        calculate_data_by_position(
+                moment,
+                GSWE_PLANET_DESCENDANT,
+                fmod(ascmc[0] + 180.0, 180.0),
+                err
+            );
+    }
 
     if (gswe_moment_has_planet(moment, GSWE_PLANET_MC)) {
         calculate_data_by_position(moment, GSWE_PLANET_MC, ascmc[1], err);
     }
+    if (gswe_moment_has_planet(moment, GSWE_PLANET_IC)) {
+        calculate_data_by_position(
+                moment,
+                GSWE_PLANET_IC,
+                fmod(ascmc[2] + 180.0, 180.0),
+                err
+            );
+    }
 
     if (gswe_moment_has_planet(moment, GSWE_PLANET_VERTEX)) {
         calculate_data_by_position(moment, GSWE_PLANET_VERTEX, ascmc[3], err);
     }
+
+    if (gswe_moment_has_planet(moment, GSWE_PLANET_ANTIVERTEX)) {
+        calculate_data_by_position(
+                moment,
+                GSWE_PLANET_ANTIVERTEX,
+                fmod(ascmc[3] + 180.0, 180.0),
+                err
+            );
+    }
 }
 
 /**

src/gswe-types.h

@@ -35,9 +35,12 @@
  * GswePlanet:
  * @GSWE_PLANET_NONE: no planet
  * @GSWE_PLANET_ASCENDANT: the ascendant
+ * @GSWE_PLANET_DESCENDANT: the descendant
  * @GSWE_PLANET_MC: midheaven (Medium Coeli)
+ * @GSWE_PLANET_IC: Immum Coeli
  * @GSWE_PLANET_VERTEX: the Vertex (the point where the ecliptic meats the
  *                      primal vertical)
+ * @GSWE_PLANET_ANTIVERTEX: the Antivertex (the point opposing the Vertex)
  * @GSWE_PLANET_MOON_NODE: the mean ascending (north) Moon node
  * @GSWE_PLANET_MOON_SOUTH_NODE: the mean descending (south) Moon node
  * @GSWE_PLANET_MOON_APOGEE: the mean Moon apogee (sometimes called Dark Moon,
@@ -80,6 +83,9 @@ typedef enum {
     GSWE_PLANET_MOON_NODE,
     GSWE_PLANET_MOON_APOGEE,
     GSWE_PLANET_MOON_SOUTH_NODE,
+    GSWE_PLANET_DESCENDANT,
+    GSWE_PLANET_IC,
+    GSWE_PLANET_ANTIVERTEX,
 
     /* Actual astrological planets */
     GSWE_PLANET_SUN = 11,

src/swe-glib.c

@@ -178,6 +178,14 @@ void gswe_init_with_dir(gchar *directory)
             9.0,
             2
         );
+    ADD_PLANET(gswe_planet_info_table, planet_info,
+               GSWE_PLANET_DESCENDANT,
+               -1,
+               FALSE,
+               _("Descendant"),
+               0.0,
+               0
+        );
     ADD_PLANET(gswe_planet_info_table, planet_info,
             GSWE_PLANET_MC,
             -1,
@@ -186,6 +194,14 @@ void gswe_init_with_dir(gchar *directory)
             5.0,
             1
         );
+    ADD_PLANET(gswe_planet_info_table, planet_info,
+               GSWE_PLANET_IC,
+               -1,
+               FALSE,
+               _("Immum Coeli"),
+               0.0,
+               0
+        );
     ADD_PLANET(gswe_planet_info_table, planet_info,
             GSWE_PLANET_VERTEX,
             -1,
@@ -194,6 +210,14 @@ void gswe_init_with_dir(gchar *directory)
             2.0,
             0
         );
+    ADD_PLANET(gswe_planet_info_table, planet_info,
+               GSWE_PLANET_ANTIVERTEX,
+               -1,
+               FALSE,
+               _("Anti-vertex"),
+               0.0,
+               0
+        );
     ADD_PLANET(gswe_planet_info_table, planet_info,
             GSWE_PLANET_MOON_NODE,
             SE_MEAN_NODE,
@@ -204,6 +228,9 @@ void gswe_init_with_dir(gchar *directory)
         );
     ADD_PLANET(gswe_planet_info_table, planet_info,
                GSWE_PLANET_MOON_SOUTH_NODE,
+               // As this is just the opposing point of the mean node,
+               // we actually calculate that, and simply add 180
+               // degrees when queried.
                SE_MEAN_NODE,
                TRUE,
                _("Descending Moon Node"),