From 029ad744b228ad21cf76c3b5148fadd853dd129b Mon Sep 17 00:00:00 2001
From: Erik Hofman <erik@ehofman.com>
Date: Thu, 22 Oct 2020 20:44:42 +0200
Subject: [PATCH] base the tides on the viewer, moon and sun longitude for an
accurate prediction.
---
src/Time/tide.cxx | 30 +++++++++++++++++-------------
src/Time/tide.hxx | 5 ++---
2 files changed, 19 insertions(+), 16 deletions(-)
diff --git a/src/Time/tide.cxx b/src/Time/tide.cxx
index b4b30eda7..b24cdbca9 100644
--- a/src/Time/tide.cxx
+++ b/src/Time/tide.cxx
@@ -29,21 +29,23 @@
#include "bodysolver.hxx"
void FGTide::reinit() {
- _prev_moon_rotation = -9999.0;
+ _prev_moon_lon = -9999.0;
}
void FGTide::bind()
{
- SGPropertyNode *prop = globals->get_props();
+ SGPropertyNode *props = globals->get_props();
- _tideAnimation = prop->getNode("/environment/sea/surface/delta-T-tide", true);
+ viewLon = props->getNode("sim/current-view/viewer-lon-deg", true);
+ _tideAnimation = props->getNode("/environment/sea/surface/delta-T-tide", true);
- _tideLevelNorm = prop->getNode("/sim/time/tide-level-norm", true);
+ _tideLevelNorm = props->getNode("/sim/time/tide-level-norm", true);
_tideLevelNorm->setDoubleValue(_tide_level);
}
void FGTide::unbind()
{
+ viewLon.reset();
_tideLevelNorm.reset();
_tideAnimation.reset();
}
@@ -51,19 +53,21 @@ void FGTide::unbind()
void FGTide::update(double dt)
{
FGLight *l = static_cast<FGLight*>(globals->get_subsystem("lighting"));
- double moon_rotation = l->get_moon_rotation();
- if (fabs(_prev_moon_rotation - moon_rotation) > (SGD_PI/180.0))
+ double moon_lon = l->get_moon_lon();
+ if (fabs(_prev_moon_lon - moon_lon) > (SGD_PI/180.0))
{
-// double sun_rotation = _sunAngleRad->getDoubleValue();
- _prev_moon_rotation = moon_rotation;
+ _prev_moon_lon = moon_lon;
- // Angles range from 0.0 (straight up) to pi (straight down).
- // The sun and moon rotate once every day (approximately) but tides
- // happen twice a day.
- _tide_level = cos(2.0*moon_rotation);
+ double sun_lon = l->get_sun_lon();
+ double viewer_lon = viewLon->getDoubleValue();
+
+ _tide_level = cos(2.0*(moon_lon - viewer_lon));
+ _tide_level += 0.1*cos(2.0*(sun_lon - viewer_lon));
+ if (_tide_level < -1.0) _tide_level = -1.0;
+ else if (_tide_level > 1.0) _tide_level = 1.0;
_tideLevelNorm->setDoubleValue(_tide_level);
- _tideAnimation->setDoubleValue(0.5 + 0.5*_tide_level);
+ _tideAnimation->setDoubleValue(0.5 - 0.5*_tide_level);
}
}
diff --git a/src/Time/tide.hxx b/src/Time/tide.hxx
index ca7c05fff..1874e8549 100644
--- a/src/Time/tide.hxx
+++ b/src/Time/tide.hxx
@@ -50,11 +50,10 @@ public:
static const char* staticSubsystemClassId() { return "tides"; }
private:
- // the rotation between the celestial object and the local horizontal
- // (in radians)
- double _prev_moon_rotation = -9999.0;
+ double _prev_moon_lon = -9999.0;
double _tide_level = 0;
+ SGPropertyNode_ptr viewLon;
SGPropertyNode_ptr _tideLevelNorm;
SGPropertyNode_ptr _tideAnimation;
};