PointConstraint.hpp

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/**************************************************************************
 * EngineSquared v0.1.1
 *
 * EngineSquared is a software package, part of the Engine² organization.
 *
 * This file is part of the EngineSquared project that is under MIT License.
 * Copyright © 2025-present by @EngineSquared, All rights reserved.
 *
 * EngineSquared is a free software: you can redistribute it and/or modify
 * it under the terms of the MIT License. See the project's LICENSE file for
 * the full license text and details.
 *
 * @file PointConstraint.hpp
 * @brief Point constraint component (3 DOF) - ball-and-socket joint
 *
 * A point constraint connects two bodies at a single point, allowing free
 * rotation around that point but no relative translation. This is useful
 * for ragdolls, pendulums, ball joints, and articulated structures.
 *
 * @author @EngineSquared
 * @version 0.1.1
 * @date 2025-12-04
 **************************************************************************/
 
#pragma once
 
#include "ConstraintSettings.hpp"
#include <Engine.hpp>
#include <glm/glm.hpp>
 
namespace Physics::Component {

struct PointConstraint {
    //========================================================================
    // Constraint Bodies
    //========================================================================

    Engine::EntityId bodyA = Engine::EntityId::Null();

    Engine::EntityId bodyB = Engine::EntityId::Null();
 
    //========================================================================
    // Attachment Points
    //========================================================================

    glm::vec3 localPointA = glm::vec3(0.0f);

    glm::vec3 localPointB = glm::vec3(0.0f);
 
    //========================================================================
    // Settings
    //========================================================================

    ConstraintSettings settings;
 
    //========================================================================
    // Runtime State
    //========================================================================

    bool broken = false;
 
    //========================================================================
    // Factory Methods
    //========================================================================

    [[nodiscard]] static PointConstraint
    Create(Engine::EntityId a, Engine::EntityId b, const glm::vec3 &pointA = glm::vec3(0.0f),
           const glm::vec3 &pointB = glm::vec3(0.0f),
           const ConstraintSettings &constraintSettings = ConstraintSettings::Rigid())
    {
        PointConstraint constraint;
        constraint.bodyA = a;
        constraint.bodyB = b;
        constraint.localPointA = pointA;
        constraint.localPointB = pointB;
        constraint.settings = constraintSettings;
        constraint.broken = false;
        return constraint;
    }

    [[nodiscard]] static PointConstraint
    CreateToWorld(Engine::EntityId body, const glm::vec3 &worldPoint,
                  const ConstraintSettings &constraintSettings = ConstraintSettings::Rigid())
    {
        PointConstraint constraint;
        constraint.bodyA = body;
        constraint.bodyB = Engine::EntityId::Null(); // Invalid entity = world
        constraint.localPointA = glm::vec3(0.0f);    // Center of body
        constraint.localPointB = worldPoint;         // World position
        constraint.settings = constraintSettings;
        constraint.broken = false;
        return constraint;
    }

    [[nodiscard]] static PointConstraint
    CreateToWorldWithOffset(Engine::EntityId body, const glm::vec3 &worldPoint, const glm::vec3 &localPoint,
                            const ConstraintSettings &constraintSettings = ConstraintSettings::Rigid())
    {
        PointConstraint constraint;
        constraint.bodyA = body;
        constraint.bodyB = Engine::EntityId::Null(); // Invalid entity = world
        constraint.localPointA = localPoint;
        constraint.localPointB = worldPoint; // World position
        constraint.settings = constraintSettings;
        constraint.broken = false;
        return constraint;
    }

    [[nodiscard]] bool IsWorldConstraint() const { return bodyB.IsNull(); }
};
 
} // namespace Physics::Component