earth.cpp

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//
// $Id: earth.cpp 2 2008-03-01 20:58:50Z kulibali $
//
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#include "space/earth.hpp"

using namespace gsgl;
using namespace gsgl::data;
using namespace gsgl::math;
using namespace gsgl::scenegraph;


namespace periapsis
{

    namespace space
    {

        BROKER_DEFINE_CREATOR(periapsis::space::planet_earth);

        const gsgl::real_t planet_earth::BARYSYSTEM_OFFSET = 4700000.0f; // distance from the earth's center to the barycentre of the earth-moon system


        planet_earth::planet_earth(const config_record & obj_config)
            : large_rocky_body(obj_config), moon(0)
        {
        } // earth::earth()


        planet_earth::~planet_earth()
        {
            moon = 0;
        } // earth::~earth()


        void planet_earth::update(context *c)
        {
            large_rocky_body::update(c);

            // find the moon if we don't already have it
            if (!moon)
            {
                for (simple_array<node *>::iterator i = get_parent()->get_children().iter(); i.is_valid(); ++i)
                {
                    if (*i && (*i)->get_name() == L"Moon")
                    {
                        moon = dynamic_cast<large_rocky_body *>(*i);
                        break;
                    }
                }
            }

            // offset the center of the planet to the real position of the earth relative to the earth-moon barysystem
            // we're one frame off, though, which is unfortunate
            if (moon)
            {
                vector moon_dir = moon->get_translation(); // the moon's position in the frame of the earth-moon barysystem
                moon_dir.normalize();

                get_translation() = moon_dir * -BARYSYSTEM_OFFSET;
            }
        } // earth::update()


    } // namespace space

} // namespace periapsis

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