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Fix tide levels to match th reported ones exactly, for today and months ahead

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This commit is contained in:
Erik Hofman 2020-10-26 10:24:33 +01:00
parent 9a54ff575c
commit f24da5ac3d
1 changed files with 10 additions and 6 deletions
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16
src/Time/tide.cxx
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@ -50,19 +50,23 @@ void FGTide::unbind()
_tideAnimation.reset();
}
#include <Main/fg_props.hxx>
void FGTide::update(double dt)
{
FGLight *l = static_cast<FGLight*>(globals->get_subsystem("lighting"));
double moon_lon = l->get_moon_lon();
if (fabs(_prev_moon_lon - moon_lon) > (SGD_PI/180.0))
// Don't know where the 60 degrees offset comes from but it matches
// the tides perfectly (at EHAL). Something to figure out.
double viewer_lon = (viewLon->getDoubleValue() + 60.0)*SGD_PI/180.0;
double moon_lon = l->get_moon_lon() - viewer_lon;
if (fabs(_prev_moon_lon - moon_lon) > (SGD_PI/360.0))
{
_prev_moon_lon = moon_lon;
double sun_lon = l->get_sun_lon();
double viewer_lon = viewLon->getDoubleValue();
double sun_lon = l->get_sun_lon() - viewer_lon;
_tide_level = cos(2.0*moon_lon);
_tide_level += 0.15*cos(2.0*sun_lon);
_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;