/**
 * Header file defining a ball.
 * A ball is the kind of real object, with a physical model, and the implicit
 * surface.
 * The physical model is strongly inspired from
 * http://www.physics-online.info/book1/chapt1/sect1a/problem1a-12/Problem1A-12.htm,
 * apart for the x-axis drift.
 * For this one, the assumption done is that the speed is divided by two at
 * each bounce, which is a reasonable assumption since it is the same for the
 * vertical bounces.
 **/
#pragma once
#include <cstddef>
#include "spheroid.hpp"
#include "FlatGround.hpp"
#include "PerlinGround.hpp"

#define G_CTE 9.81

class Ball {
    private:
        Point Center;
        Spheroid surface;
        const Ground* ground;
        double radius;
        double init_h;
        double min_height;
        size_t bounce_number;
        double crt_time;
        double A, B, U, T; // Coefficients for the physical model.
        double v_x, v_z;
        void _compute_pos(double dt);
        void _compute_parameters();
        void _compute_v_x(Point normal);
        void _compute_v_z(Point normal);
        void _compute_A_n();
        void _compute_B_n();
        void _compute_U_n();
        void _compute_T_n();
    public:
        Ball(const Point& _center, const Ground* ground, double _min_height, double _v_x,
                double _v_z, double p, double q);
        void update_pos(double dt);
        Point getCenter() const {return Center;}
        double accessT() const { return T;}
        double access_crt_time() const { return crt_time;}
        Spheroid* get_surface() { return &surface; }
};

std::ostream& operator << (std::ostream &out, Ball const& data);