claudes_game/src/simulation.h

#ifndef BODIES_H
#define BODIES_H

#include "physics.h"

// Celestial body structure
struct CelestialBody {
    char name[64];
    double mass;              // kg
    double radius;            // meters
    Vec3 local_position;      // position relative to parent (meters)
    Vec3 local_velocity;      // velocity relative to parent (m/s)
    Vec3 position;            // global position (meters from origin)
    Vec3 velocity;            // global velocity (m/s)
    double soi_radius;        // sphere of influence radius (meters)
    int parent_index;         // index of gravitational parent (-1 for root body like Sun)
    float color[3];           // RGB color for rendering
    double eccentricity;      // orbital eccentricity (0 = circular, <1 = elliptical)
    double semi_major_axis;   // meters
};

// Simulation state
struct SimulationState {
    CelestialBody* bodies;
    int body_count;
    int max_bodies;
    double time;              // simulation time (seconds)
    double dt;                // time step (seconds)
};

// Simulation management functions
SimulationState* create_simulation(int max_bodies, double time_step);
void destroy_simulation(SimulationState* sim);

// SOI and simulation update functions
int find_dominant_body(SimulationState* sim, int body_index);
void update_soi(CelestialBody* body, CelestialBody* parent, double semi_major_axis);
void update_simulation(SimulationState* sim);

// Velocity initialization
void calculate_initial_velocities(SimulationState* sim);

// SOI helpers
void calculate_soi_radii(SimulationState* sim);

// Coordinate frame management
void initialize_local_coordinates(SimulationState* sim);
void compute_global_coordinates(SimulationState* sim);

// Orbital elements calculation
struct OrbitalElements {
    double time_days;
    double semi_major_axis_au;
    double eccentricity;
    double specific_energy;
    double distance_to_sun_au;
    double distance_to_ref_body_au;
    double velocity_magnitude;
};

OrbitalElements calculate_orbital_elements(CelestialBody* body, CelestialBody* primary,
                                           CelestialBody* optional_ref_body, double current_time);

#endif