/*
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* Copyright (C) 2023 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ANTKEEPER_PHYSICS_SPRING_CONSTRAINT_HPP
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#define ANTKEEPER_PHYSICS_SPRING_CONSTRAINT_HPP
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#include <engine/physics/kinematics/constraint.hpp>
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#include <engine/physics/kinematics/rigid-body.hpp>
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#include <engine/math/vector.hpp>
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namespace physics {
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/**
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* Spring constraint.
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*/
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class spring_constraint: public constraint
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{
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public:
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void solve(float dt) override;
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/**
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* Attaches the spring to body a.
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*
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* @param body_a Body to which the spring should be attached.
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* @param point_a Point on body a, in body-space, at which the spring should be attached.
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*/
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inline void attach_a(rigid_body& body_a, const math::fvec3& point_a) noexcept
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{
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m_body_a = &body_a;
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m_point_a = point_a;
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}
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/**
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* Attaches the spring to body b.
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*
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* @param body_b Body to which the spring should be attached.
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* @param point_b Point on body b, in body-space, at which the spring should be attached.
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*/
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inline void attach_b(rigid_body& body_b, const math::fvec3& point_b) noexcept
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{
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m_body_b = &body_b;
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m_point_b = point_b;
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}
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/**
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* Detaches the spring from body a.
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*/
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inline void detach_a() noexcept
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{
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m_body_a = nullptr;
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}
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/**
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* Detaches the spring from body b.
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*/
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inline void detach_b() noexcept
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{
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m_body_b = nullptr;
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}
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/**
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* Detaches the spring from bodies a and b.
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*/
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inline void detach() noexcept
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{
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detach_a();
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detach_b();
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}
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/**
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* Sets the resting length of the spring.
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*
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* @param length Resting length, in meters.
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*/
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inline void set_resting_length(float length) noexcept
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{
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m_resting_length = length;
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}
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/**
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* Sets the stiffness constant of the spring.
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*
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* @param stiffness Stiffness constant.
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*/
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inline void set_stiffness(float stiffness) noexcept
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{
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m_stiffness = stiffness;
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}
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/**
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* Sets the damping constant of the spring.
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*
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* @param damping Damping constant.
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*/
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inline void set_damping(float damping) noexcept
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{
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m_damping = damping;
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}
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/// Returns the body to which the spring is attached at point a.
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[[nodiscard]] inline rigid_body* get_body_a() const noexcept
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{
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return m_body_a;
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}
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/// Returns the body to which the spring is attached at point b.
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[[nodiscard]] inline rigid_body* get_body_b() const noexcept
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{
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return m_body_b;
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}
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/// Returns the point at which the spring is attached to body a, in body-space.
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[[nodiscard]] inline const math::fvec3& get_point_a() const noexcept
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{
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return m_point_a;
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}
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/// Returns the point at which the spring is attached to body b, in body-space.
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[[nodiscard]] inline const math::fvec3& get_point_b() const noexcept
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{
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return m_point_b;
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}
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/// Returns the resting length of the spring, in meters.
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[[nodiscard]] inline float get_resting_length() const noexcept
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{
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return m_resting_length;
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}
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/// Returns the stiffness constant of the spring.
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[[nodiscard]] inline float get_stiffness() const noexcept
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{
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return m_stiffness;
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}
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/// Returns the damping constant of the spring.
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[[nodiscard]] inline float get_damping() const noexcept
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{
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return m_damping;
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}
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private:
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/// Rigid body to which the spring is attached at point a.
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rigid_body* m_body_a{nullptr};
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/// Rigid body to which the spring is attached at point b.
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rigid_body* m_body_b{nullptr};
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/// Point at which the spring is attached to body a, in body-space.
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math::fvec3 m_point_a{0.0f, 0.0f, 0.0f};
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/// Point at which the spring is attached to body b, in body-space.
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math::fvec3 m_point_b{0.0f, 0.0f, 0.0f};
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/// Resting length of the spring, in meters.
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float m_resting_length{0.0f};
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/// Stiffness constant of the spring.
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float m_stiffness{1.0f};
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/// Damping constant of the spring.
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float m_damping{1.0f};
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};
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} // namespace physics
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#endif // ANTKEEPER_PHYSICS_SPRING_CONSTRAINT_HPP
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