vehicle_body.h

#ifndef VEHICLE_BODY_H
#define VEHICLE_BODY_H

#include "scene/3d/physics_body.h"

class VehicleBody;

class VehicleWheel : public Spatial {

    OBJ_TYPE(VehicleWheel,Spatial);

friend class VehicleBody;


    Transform m_worldTransform;
    Transform local_xform;
    bool engine_traction;
    bool steers;


    Vector3 m_chassisConnectionPointCS; //const
    Vector3 m_wheelDirectionCS;//const
    Vector3 m_wheelAxleCS; // const or modified by steering

    real_t m_suspensionRestLength;
    real_t m_maxSuspensionTravelCm;
    real_t m_wheelRadius;

    real_t m_suspensionStiffness;
    real_t m_wheelsDampingCompression;
    real_t m_wheelsDampingRelaxation;
    real_t m_frictionSlip;
    real_t m_maxSuspensionForce;
    bool m_bIsFrontWheel;

    VehicleBody *body;

//  btVector3   m_wheelAxleCS; // const or modified by steering ?

    real_t  m_steering;
    real_t  m_rotation;
    real_t  m_deltaRotation;
    real_t  m_rollInfluence;
    //real_t    m_engineForce;
    real_t  m_brake;

    real_t  m_clippedInvContactDotSuspension;
    real_t  m_suspensionRelativeVelocity;
    //calculated by suspension
    real_t  m_wheelsSuspensionForce;
    real_t  m_skidInfo;


    struct RaycastInfo {
        //set by raycaster
        Vector3 m_contactNormalWS;//contactnormal
        Vector3 m_contactPointWS;//raycast hitpoint
        real_t  m_suspensionLength;
        Vector3 m_hardPointWS;//raycast starting point
        Vector3 m_wheelDirectionWS; //direction in worldspace
        Vector3 m_wheelAxleWS; // axle in worldspace
        bool m_isInContact;
        PhysicsBody* m_groundObject; //could be general void* ptr
    } m_raycastInfo;

    void _update(PhysicsDirectBodyState *s);

protected:
    void _notification(int p_what);
    static void _bind_methods();

public:

    void set_radius(float p_radius);
    float get_radius() const;

    void set_suspension_rest_length(float p_length);
    float get_suspension_rest_length() const;

    void set_suspension_travel(float p_length);
    float get_suspension_travel() const;

    void set_suspension_stiffness(float p_value);
    float get_suspension_stiffness() const;

    void set_suspension_max_force(float p_value);
    float get_suspension_max_force() const;

    void set_damping_compression(float p_value);
    float get_damping_compression() const;

    void set_damping_relaxation(float p_value);
    float get_damping_relaxation() const;

    void set_friction_slip(float p_value);
    float get_friction_slip() const;

    void set_use_as_traction(bool p_enable);
    bool is_used_as_traction() const;

    void set_use_as_steering(bool p_enabled);
    bool is_used_as_steering() const;

    VehicleWheel();

};


class VehicleBody : public PhysicsBody {

    OBJ_TYPE(VehicleBody,PhysicsBody);

    real_t mass;
    real_t friction;

    float engine_force;
    float brake;

    Vector3 linear_velocity;
    Vector3  angular_velocity;
    bool ccd;

    real_t  m_pitchControl;
    real_t  m_steeringValue;
    real_t  m_currentVehicleSpeedKmHour;

    Set<RID> exclude;

    Vector<Vector3> m_forwardWS;
    Vector<Vector3> m_axle;
    Vector<real_t>  m_forwardImpulse;
    Vector<real_t>  m_sideImpulse;

    struct btVehicleWheelContactPoint {
        PhysicsDirectBodyState *m_s;
        PhysicsBody* m_body1;
        Vector3 m_frictionPositionWorld;
        Vector3 m_frictionDirectionWorld;
        real_t  m_jacDiagABInv;
        real_t  m_maxImpulse;


        btVehicleWheelContactPoint(PhysicsDirectBodyState *s,PhysicsBody* body1,const Vector3& frictionPosWorld,const Vector3& frictionDirectionWorld, real_t maxImpulse);
    };

    void _resolve_single_bilateral(PhysicsDirectBodyState *s, const Vector3& pos1, PhysicsBody* body2, const Vector3& pos2, const Vector3& normal, real_t& impulse);
    real_t _calc_rolling_friction(btVehicleWheelContactPoint& contactPoint);

    void _update_friction(PhysicsDirectBodyState *s);
    void _update_suspension(PhysicsDirectBodyState *s);
    real_t _ray_cast(int p_idx,PhysicsDirectBodyState *s);
    void _update_wheel_transform(VehicleWheel& wheel ,PhysicsDirectBodyState *s);
    void _update_wheel(int p_idx,PhysicsDirectBodyState *s);



friend class VehicleWheel;
    Vector<VehicleWheel*> wheels;

    static void _bind_methods();

    void _direct_state_changed(Object *p_state);
public:


    void set_mass(real_t p_mass);
    real_t get_mass() const;

    void set_friction(real_t p_friction);
    real_t get_friction() const;

    void set_engine_force(float p_engine_force);
    float get_engine_force() const;

    void set_brake(float p_force);
    float get_brake() const;

    void set_steering(float p_steering);
    float get_steering() const;


    VehicleBody();
};

#endif // VEHICLE_BODY_H