PointMassGravityModel.h

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/*
Point mass gravity model header file

Author: Alex Reynolds
*/
/*
Metadata for MS GUI:
imdata = {"exclude" : True}
*/

#ifndef MODELS_ENVIRONMENT_POINT_MASS_GRAVITY_MODEL
#define MODELS_ENVIRONMENT_POINT_MASS_GRAVITY_MODEL

#include "simulation/Model.h"
#include "frames/Frame.h"
#include "frames/Node.h"
#include "frames/frameutils.h"
#include "constants/planetdefaults.h"

namespace warptwin {

    /**
     * @brief   Point mass gravity model
     * 
     * This model generates forces acting on a body under the influence of a 
     * simple point mass gravity field. 
    */
    MODEL(PointMassGravityModel)
    public:
        // TODO: Replace need for mass with direct acceleration calculation when 
        // body accel methods are implemented
        // Model params
        //         NAME                     TYPE                    DEFAULT VALUE
        START_PARAMS
            /** This is the gravitational parameter of our parent planet. Defaults to
             * Earth's gravitational parameter for ease of use */
            SIGNAL(mu,                      double,                 warpos::earth_wgs84.mu)
            /** This is the mass of the body, which will be multiplied by our force
             *  to get the force calculation... TODO to replace this with accel methods */
            SIGNAL(body_mass,               double,                 1.0)
        END_PARAMS

        // Model inputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_INPUTS
            /** The position of the object body in the reference frame f */
            SIGNAL(pos_body__f,             CartesianVector3,      CartesianVector3({0.0, 0.0, 0.0}))
        END_INPUTS

        // Model outputs
        //         NAME                     TYPE                    DEFAULT VALUE
        START_OUTPUTS
            /** This is the acceleration due to gravity calculated in the same reference frame as pos_body__f */
            SIGNAL(grav_force__f,           CartesianVector3,      CartesianVector3({0.0, 0.0, 0.0}))
        END_OUTPUTS

    protected:
        int16 execute() override; 

        // Temporary vectors and variables to carry out our calculations
        double _r;
        double _multiplier;
        CartesianVector3 _grav_force__planet;
    };
}

#endif