1 files changed, 34 insertions, 0 deletions
diff --git a/src/geod_interface.c b/src/geod_interface.c
new file mode 100644
index 00000000..c144a35d
--- /dev/null
+++ b/src/geod_interface.c
@@ -0,0 +1,34 @@
+#include "projects.h"
+#include "geod_interface.h"
+
+void geod_ini(void) {
+  GeodesicInit(&GlobalGeodesic, geod_a, geod_f);
+}
+
+void geod_pre(void) {
+  double
+    degree = PI/180,
+    lat1 = phi1 / degree, lon1 = lam1 /degree, azi1 = al12 / degree;
+  GeodesicLineInit(&GlobalGeodesicLine, &GlobalGeodesic,
+		   lat1, lon1, azi1, 0U);
+}
+
+void geod_for(void) {
+  double degree = PI/180, s12 = geod_S, lat2, lon2, azi2;
+  Position(&GlobalGeodesicLine, s12, &lat2, &lon2, &azi2);
+  azi2 += azi2 >= 0 ? -180 : 180; /* Compute back azimuth */
+  phi2 = lat2 * degree;
+  lam2 = lon2 * degree;
+  al21 = azi2 * degree;
+}
+
+void geod_inv(void) {
+  double
+    degree = PI / 180,
+    lat1 = phi1 / degree, lon1 = lam1 / degree,
+    lat2 = phi2 / degree, lon2 = lam2 / degree,
+    azi1, azi2, s12;
+  Inverse(&GlobalGeodesic, lat1, lon1, lat2, lon2, &s12, &azi1, &azi2);
+  azi2 += azi2 >= 0 ? -180 : 180; /* Compute back azimuth */
+  al12 = azi1 * degree; al21 = azi2 * degree; geod_S = s12;
+}