src/solar.*: Add solar elevation calculation from Redshift

1 files changed, 32 insertions, 0 deletions

diff --git a/src/solar.h b/src/solar.h
new file mode 100644
index 0000000..b1faed9
--- /dev/null
+++ b/src/solar.h
@@ -0,0 +1,32 @@
+/*
+ * Parts of this file have been taken from the Redshift project:
+ * https://github.com/jonls/redshift/
+ *
+ * Copyright 2010 Jon Lund Steffensen
+ * Copyright 2023 Robert Tari
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *   Jon Lund Steffensen <jonlst@gmail.com>
+ *   Robert Tari <robert@tari.in>
+ */
+
+#ifndef REDSHIFT_SOLAR_H
+#define REDSHIFT_SOLAR_H
+
+#define SOLAR_CIVIL_TWILIGHT_ELEV    -6.0
+
+double solar_elevation(double date, double lat, double lon);
+
+#endif /* ! REDSHIFT_SOLAR_H */