src/main/java/eu/m724/wtapi/object/Twilight.java

@@ -8,20 +8,9 @@ import java.time.LocalDateTime;
  * @param date    The date this object contains times for
  * @param sunrise Time of sunrise
  * @param sunset  Time of sunset
- * @param solarNoon Time of solar noon in the current day.<br>
- *                  If polar night, the solar noon still applies, because the sun still exists, but doesn't rise above the horizon.
- * @param polar   Is polar cycle
  */
-public record Twilight(LocalDate date, LocalDateTime sunrise, LocalDateTime sunset, LocalDateTime solarNoon, boolean polar) {
+public record Twilight(LocalDate date, LocalDateTime sunrise, LocalDateTime sunset) {
     public Duration getDayLength() {
         return Duration.between(sunrise, sunset);
     }
-
-    public boolean isPolarNight() {
-        return polar && Duration.between(sunrise, sunset).isNegative();
-    }
-
-    public boolean isPolarDay() {
-        return polar && !isPolarNight();
-    }
 }

src/main/java/eu/m724/wtapi/provider/twilight/impl/approximate/ApproximateTwilightTimeProvider.java

@@ -5,7 +5,6 @@ import eu.m724.wtapi.object.Twilight;
 import eu.m724.wtapi.provider.twilight.CacheableTwilightTimeProvider;
 
 import java.time.LocalDate;
-import java.time.LocalDateTime;
 
 import static java.lang.Math.*;
 
@@ -22,14 +21,10 @@ public class ApproximateTwilightTimeProvider extends CacheableTwilightTimeProvid
         double equationOfTime = cache.equationOfTime();
 
         double latRad = toRadians(coordinates.latitude);
-        double solarNoon = 720 - 4 * coordinates.longitude - equationOfTime;
+        double hourAngle = hourAngle(latRad, declination);
-        LocalDateTime solarNoonDateTime = cache.date().atStartOfDay().plusSeconds((long) (solarNoon * 60));
+        System.out.println(hourAngle);
 
-        // 90.833 deg = 1.5853349194640094 rad
+        if (Double.isNaN(hourAngle)) {
-        double n1 = cos(1.5853349194640094) / (cos(latRad) * cos(declination));
-        n1 -= tan(latRad) * tan(declination);
-
-        if (n1 < -1) { // polar day
             LocalDate sunriseDate = step(cache.date().minusDays(1), latRad, -1);
             LocalDate sunsetDate = step(cache.date().plusDays(1), latRad, 1);
 
@@ -39,57 +34,46 @@ public class ApproximateTwilightTimeProvider extends CacheableTwilightTimeProvid
             return new Twilight(
                     cache.date(),
                     backwardTwilight.sunrise(),
-                    forwardTwilight.sunset(),
+                    forwardTwilight.sunset()
-                    solarNoonDateTime,
-                    true
-            );
-        } else if (n1 > 1) { // polar night
-            LocalDate sunriseDate = step(cache.date().plusDays(1), latRad, 1);
-            LocalDate sunsetDate = step(cache.date().minusDays(1), latRad, -1);
-
-            Twilight backwardTwilight = calculateTwilightTime(sunriseDate, coordinates);
-            Twilight forwardTwilight = calculateTwilightTime(sunsetDate, coordinates);
-
-            return new Twilight(
-                    cache.date(),
-                    backwardTwilight.sunrise(),
-                    forwardTwilight.sunset(),
-                    solarNoonDateTime,
-                    true
             );
         }
 
-        double hourAngle = acos(n1);
         double longitudeEffect = 4 * toDegrees(hourAngle);
 
         // sunrise = 720 - 4 * (coordinates.longitude + hourAngleDeg) - equationOfTime
         // sunset = 720 - 4 * (coordinates.longitude - hourAngleDeg) - equationOfTime
+        double solarNoon = 720 - 4 * coordinates.longitude - equationOfTime;
         double sunrise = solarNoon - longitudeEffect;
         double sunset = solarNoon + longitudeEffect;
 
         return new Twilight(
                 cache.date(),
                 cache.date().atStartOfDay().plusMinutes((long) sunrise),
-                cache.date().atStartOfDay().plusMinutes((long) sunset),
+                cache.date().atStartOfDay().plusMinutes((long) sunset)
-                solarNoonDateTime,
-                false
         );
     }
 
     private LocalDate step(LocalDate date, double latRad, int direction) {
         double declination = getDeclination(getFractionalYear(date));
 
-        //System.out.println("Step date: " + date);
+        System.out.println("Step date: " + date);
-        double n1 = cos(1.5853349194640094) / (cos(latRad) * cos(declination));
+        double hourAngle = hourAngle(latRad, declination);
-        n1 -= tan(latRad) * tan(declination);
+        if (Double.isNaN(hourAngle)) {
-        if (n1 < -1 || n1 > 1) {
             return step(date.plusDays(direction), latRad, direction);
         }
 
-        //System.out.println("this the one");
+        System.out.println("this the one");
         return date;
     }
 
+    private double hourAngle(double latRad, double declination) {
+        // 90.833 deg = 1.5853349194640094 rad
+        double n1 = cos(1.5853349194640094) / (cos(latRad) * cos(declination));
+        double n2 = tan(latRad) * tan(declination);
+        System.out.println(n1 - n2);
+        return acos(n1 - n2);
+    }
+
     @Override
     public ApproximateTwilightTimeCache initializeCache(LocalDate date) {
         double fractionalYear = getFractionalYear(date);

src/test/java/eu/m724/wtapi/twilight/ApproximateTwilightTimeTest.java

@@ -23,24 +23,22 @@ public class ApproximateTwilightTimeTest {
         TwilightTimeProvider provider = new ApproximateTwilightTimeProvider();
 
         // used https://gml.noaa.gov/grad/solcalc/index.html for reference values
-        testLocation(provider, 26, 6, 2023, 53.123394, 23.0864867, LocalDateTime.of(2023, 6, 26, 2, 2), LocalDateTime.of(2023, 6, 26, 18, 59), 0);
+        testLocation(provider, 26, 6, 2023, 53.123394, 23.0864867, LocalDateTime.of(2023, 6, 26, 2, 2), LocalDateTime.of(2023, 6, 26, 18, 59));
-        testLocation(provider, 13, 11, 2040, 45.432427, -122.3899276, LocalDateTime.of(2040, 11, 13, 15, 7), LocalDateTime.of(2040, 11, 14, 0, 41), 0);
+        testLocation(provider, 13, 11, 2040, 45.432427, -122.3899276, LocalDateTime.of(2040, 11, 13, 15, 7), LocalDateTime.of(2040, 11, 14, 0, 41));
-        testLocation(provider, 23, 3, 2021, 55.5024161, 9.6801853, LocalDateTime.of(2021, 3, 23, 5, 15), LocalDateTime.of(2021, 3, 23, 17, 41), 0);
+        testLocation(provider, 23, 3, 2021, 55.5024161, 9.6801853, LocalDateTime.of(2021, 3, 23, 5, 15), LocalDateTime.of(2021, 3, 23, 17, 41));
-        testLocation(provider, 6, 8,1990, -72.012117, 2.5240873, LocalDateTime.of(1990, 8, 6, 10, 0), LocalDateTime.of(1990, 8, 6, 13, 52),0);
+        testLocation(provider, 6, 8,1990, -72.012117, 2.5240873, LocalDateTime.of(1990, 8, 6, 10, 0), LocalDateTime.of(1990, 8, 6, 13, 52));
         // TODO this is broken (very inaccurate) so fix
         ACCEPTABLE_DIFFERENCE = 172800; // 2 days
-        testLocation(provider, 5, 9,2021, 82.498665, -62.3458366, LocalDateTime.of(2021, 4, 5, 20, 55), LocalDateTime.of(2021, 9, 6, 18, 22), 1); // the reference values might be incorrect
+        testLocation(provider, 5, 9,2021, 82.498665, -62.3458366, LocalDateTime.of(2021, 4, 5, 20, 55), LocalDateTime.of(2021, 9, 6, 18, 22)); // the reference values might be incorrect
-        testLocation(provider, 3, 2,2021, 82.498665, -62.3458366, LocalDateTime.of(2021, 2, 27, 7, 24), LocalDateTime.of(2020, 10, 13, 8, 46), -1); // the reference values might be incorrect
     }
 
-    private void testLocation(TwilightTimeProvider provider, int day, int month, int year, double latitude, double longitude, LocalDateTime actualSunrise, LocalDateTime actualSunset, int polar) {
+    private void testLocation(TwilightTimeProvider provider, int day, int month, int year, double latitude, double longitude, LocalDateTime actualSunrise, LocalDateTime actualSunset) {
         LocalDate date = LocalDate.of(year, month, day);
         Coordinates coordinates = new Coordinates(latitude, longitude);
 
         Twilight twilight = provider.calculateTwilightTime(date, coordinates);
         System.out.println(date);
         System.out.println(coordinates.latitude + " " + coordinates.longitude);
-        System.out.println("Solar noon: " + twilight.solarNoon());
 
         System.out.println("Calculated sunrise: " + twilight.sunrise());
         System.out.println("Actual sunrise: " + actualSunrise);
@@ -50,8 +48,6 @@ public class ApproximateTwilightTimeTest {
         System.out.println("Actual sunset: " + actualSunset);
         assert Duration.between(twilight.sunset(), actualSunset).abs().getSeconds() < ACCEPTABLE_DIFFERENCE;
 
-        assert polar == (twilight.isPolarDay() ? 1 : twilight.isPolarNight() ? -1 : 0);
-
         System.out.println();
     }
 }

src/test/java/eu/m724/wtapi/twilight/MockTwilightTimeProvider.java

@@ -16,9 +16,7 @@ public class MockTwilightTimeProvider extends TwilightTimeProvider {
         return new Twilight(
                 date,
                 date.atStartOfDay().plusSeconds(-time),
-                date.atStartOfDay().plusSeconds(time),
+                date.atStartOfDay().plusSeconds(time)
-                date.atStartOfDay().plusMinutes(62),
-                false
         );
     }
 }