constants.hpp

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#ifndef CONSTANTS_HPP
#define CONSTANTS_HPP
 
/**
 * \file constants.hpp
 * \brief Constants for the model.
 * \author Le Bars, Yoann
 *
 * This file is part of the pure C++ benchmark.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <https://www.gnu.org/licenses/>.
 */
 
/**
 * \brief Contains all classes and constants for the core physics simulation.
 * \defgroup ModelConstants Simulation Constants
 * @{
 */
namespace Model {
    /// \brief Default computing precision value.
    constexpr double EPSILON = 1e-6;
 
    /// \brief Default universal gravitational constant (in m³⋅kg⁻¹⋅s⁻²).
    constexpr double G = 6.67430e-11;
 
    /// \brief Heuristic for the maximum distance a body should travel in one
    ///        step, used for adaptive time stepping.
    constexpr double TARGET_DX = 0.01;
 
    /// \brief Maximum time step allowed for the simulation to ensure stability.
    constexpr double MAX_DT = 0.01;
 
    /// \brief Coefficient of restitution for collisions (e.g., 0.8 for a very
    ///        bouncy ball).
    constexpr double COEFF_RESTITUTION = 0.1;
 
    /// \brief Coefficient of static friction.
    constexpr double COEFF_STATIC_FRICTION = 0.8;
 
    /// \brief Coefficient of kinetic (sliding) friction, also known as dynamic
    ///        friction.
    constexpr double COEFF_FRICTION = 0.6;
 
    /// \brief Damping factor for smoothing adaptive time step changes.
    constexpr double DT_DAMPING_FACTOR = 0.1;
 
    /// \brief The percentage of overlap to correct per frame (Baumgarte
    ///        stabilisation).
    constexpr double POSITIONAL_CORRECTION_FACTOR = 0.2;
 
    /// \brief Damping factor for linear velocity.
    constexpr double LINEAR_DAMPING = 0.005;
 
    /// \brief Damping factor for angular velocity.
    constexpr double ANGULAR_DAMPING = 0.005;
 
    /// \brief Default frequency for logging system energy.
    constexpr int DEFAULT_LOG_FREQ = 100;
 
    // --- Initial Conditions ---
    /// \brief Minimum mass for randomly generated bodies.
    constexpr double MIN_BODY_MASS = 25.0;
 
    /// \brief Maximum mass for randomly generated bodies.
    constexpr double MAX_BODY_MASS = 75.0;
 
    /// \brief Minimum initial velocity component for randomly generated bodies.
    constexpr double MIN_INITIAL_VELOCITY = -5.0;
 
    /// \brief Maximum initial velocity component for randomly generated bodies.
    constexpr double MAX_INITIAL_VELOCITY = 5.0;
 
    /// \brief Maximum initial angular velocity component for randomly generated
    ///        bodies (in rad/s).
    constexpr double MAX_INITIAL_ANGULAR_VELOCITY = 0.5;
 
    /// \brief Heuristic scaling factor for the initial placement volume of
    /// bodies.
    constexpr double PLACEMENT_SCALE_FACTOR = 4.0;
 
    /// \brief The number of "settling" steps to run at the start of the
    /// simulation.
    constexpr int SETTLING_STEPS = 5;
 
    // --- UI and Visualization ---
    /// \brief Scaling factor for the length of the torque visualization arrow.
    constexpr double TORQUE_ARROW_SCALE = 0.1;
 
    /// \brief Scaling factor for the length of the angular acceleration arrow.
    constexpr double ALPHA_ARROW_SCALE = 1.0;
}
/** @} */
 
#endif  // CONSTANTS_HPP