Box2D b2World in class

So I've got:

class bc_Game
{
public:
//blah
private:
b2World world;
};

bc_Game::bc_Game()
{
//blah, defining variables used
world = b2World(gravity, sleep);
}

Now, I just get error: no matching function for call to 'b2World::b2World()' note: candidates are: b2World::b2World(const b2Vec2&, bool) note: b2World::b2World(const b2World&)

I've got no idea how to get this to work, I've tried std::auto_ptr, new b2World, everything I could think of.

b2World is part of Box2D, but here goes...

 
/*
* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/

#ifndef B2_WORLD_H
#define B2_WORLD_H

#include 
#include 
#include 
#include 
#include 

struct b2AABB;
struct b2BodyDef;
struct b2JointDef;
struct b2TimeStep;
class b2Body;
class b2Fixture;
class b2Joint;

/// The world class manages all physics entities, dynamic simulation,
/// and asynchronous queries. The world also contains efficient memory
/// management facilities.
class b2World
{
public:
    /// Construct a world object.
    /// @param gravity the world gravity vector.
    /// @param doSleep improve performance by not simulating inactive bodies.
    b2World(const b2Vec2& gravity, bool doSleep);

    /// Destruct the world. All physics entities are destroyed and all heap memory is released.
    ~b2World();

    /// Register a destruction listener. The listener is owned by you and must
    /// remain in scope.
    void SetDestructionListener(b2DestructionListener* listener);

    /// Register a contact filter to provide specific control over collision.
    /// Otherwise the default filter is used (b2_defaultFilter). The listener is
    /// owned by you and must remain in scope. 
    void SetContactFilter(b2ContactFilter* filter);

    /// Register a contact event listener. The listener is owned by you and must
    /// remain in scope.
    void SetContactListener(b2ContactListener* listener);

    /// Register a routine for debug drawing. The debug draw functions are called
    /// inside with b2World::DrawDebugData method. The debug draw object is owned
    /// by you and must remain in scope.
    void SetDebugDraw(b2DebugDraw* debugDraw);

    /// Create a rigid body given a definition. No reference to the definition
    /// is retained.
    /// @warning This function is locked during callbacks.
    b2Body* CreateBody(const b2BodyDef* def);

    /// Destroy a rigid body given a definition. No reference to the definition
    /// is retained. This function is locked during callbacks.
    /// @warning This automatically deletes all associated shapes and joints.
    /// @warning This function is locked during callbacks.
    void DestroyBody(b2Body* body);

    /// Create a joint to constrain bodies together. No reference to the definition
    /// is retained. This may cause the connected bodies to cease colliding.
    /// @warning This function is locked during callbacks.
    b2Joint* CreateJoint(const b2JointDef* def);

    /// Destroy a joint. This may cause the connected bodies to begin colliding.
    /// @warning This function is locked during callbacks.
    void DestroyJoint(b2Joint* joint);

    /// Take a time step. This performs collision detection, integration,
    /// and constraint solution.
    /// @param timeStep the amount of time to simulate, this should not vary.
    /// @param velocityIterations for the velocity constraint solver.
    /// @param positionIterations for the position constraint solver.
    void Step(  float32 timeStep,
                int32 velocityIterations,
                int32 positionIterations);

    /// Call this after you are done with time steps to clear the forces. You normally
    /// call this after each call to Step, unless you are performing sub-steps. By default,
    /// forces will be automatically cleared, so you don't need to call this function.
    /// @see SetAutoClearForces
    void ClearForces();

   开发者_JAVA百科 /// Call this to draw shapes and other debug draw data.
    void DrawDebugData();

    /// Query the world for all fixtures that potentially overlap the
    /// provided AABB.
    /// @param callback a user implemented callback class.
    /// @param aabb the query box.
    void QueryAABB(b2QueryCallback* callback, const b2AABB& aabb) const;

    /// Ray-cast the world for all fixtures in the path of the ray. Your callback
    /// controls whether you get the closest point, any point, or n-points.
    /// The ray-cast ignores shapes that contain the starting point.
    /// @param callback a user implemented callback class.
    /// @param point1 the ray starting point
    /// @param point2 the ray ending point
    void RayCast(b2RayCastCallback* callback, const b2Vec2& point1, const b2Vec2& point2) const;

    /// Get the world body list. With the returned body, use b2Body::GetNext to get
    /// the next body in the world list. A NULL body indicates the end of the list.
    /// @return the head of the world body list.
    b2Body* GetBodyList();

    /// Get the world joint list. With the returned joint, use b2Joint::GetNext to get
    /// the next joint in the world list. A NULL joint indicates the end of the list.
    /// @return the head of the world joint list.
    b2Joint* GetJointList();

    /// Get the world contact list. With the returned contact, use b2Contact::GetNext to get
    /// the next contact in the world list. A NULL contact indicates the end of the list.
    /// @return the head of the world contact list.
    /// @warning contacts are 
    b2Contact* GetContactList();

    /// Enable/disable warm starting. For testing.
    void SetWarmStarting(bool flag) { m_warmStarting = flag; }

    /// Enable/disable continuous physics. For testing.
    void SetContinuousPhysics(bool flag) { m_continuousPhysics = flag; }

    /// Get the number of broad-phase proxies.
    int32 GetProxyCount() const;

    /// Get the number of bodies.
    int32 GetBodyCount() const;

    /// Get the number of joints.
    int32 GetJointCount() const;

    /// Get the number of contacts (each may have 0 or more contact points).
    int32 GetContactCount() const;

    /// Change the global gravity vector.
    void SetGravity(const b2Vec2& gravity);

    /// Get the global gravity vector.
    b2Vec2 GetGravity() const;

    /// Is the world locked (in the middle of a time step).
    bool IsLocked() const;

    /// Set flag to control automatic clearing of forces after each time step.
    void SetAutoClearForces(bool flag);

    /// Get the flag that controls automatic clearing of forces after each time step.
    bool GetAutoClearForces() const;

private:

    // m_flags
    enum
    {
        e_newFixture    = 0x0001,
        e_locked        = 0x0002,
        e_clearForces   = 0x0004,
    };

    friend class b2Body;
    friend class b2ContactManager;
    friend class b2Controller;

    void Solve(const b2TimeStep& step);
    void SolveTOI();
    void SolveTOI(b2Body* body);

    void DrawJoint(b2Joint* joint);
    void DrawShape(b2Fixture* shape, const b2Transform& xf, const b2Color& color);

    b2BlockAllocator m_blockAllocator;
    b2StackAllocator m_stackAllocator;

    int32 m_flags;

    b2ContactManager m_contactManager;

    b2Body* m_bodyList;
    b2Joint* m_jointList;

    int32 m_bodyCount;
    int32 m_jointCount;

    b2Vec2 m_gravity;
    bool m_allowSleep;

    b2Body* m_groundBody;

    b2DestructionListener* m_destructionListener;
    b2DebugDraw* m_debugDraw;

    // This is used to compute the time step ratio to
    // support a variable time step.
    float32 m_inv_dt0;

    // This is for debugging the solver.
    bool m_warmStarting;

    // This is for debugging the solver.
    bool m_continuousPhysics;
};

inline b2Body* b2World::GetBodyList()
{
    return m_bodyList;
}

inline b2Joint* b2World::GetJointList()
{
    return m_jointList;
}

inline b2Contact* b2World::GetContactList()
{
    return m_contactManager.m_contactList;
}

inline int32 b2World::GetBodyCount() const
{
    return m_bodyCount;
}

inline int32 b2World::GetJointCount() const
{
    return m_jointCount;
}

inline int32 b2World::GetContactCount() const
{
    return m_contactManager.m_contactCount;
}

inline void b2World::SetGravity(const b2Vec2& gravity)
{
    m_gravity = gravity;
}

inline b2Vec2 b2World::GetGravity() const
{
    return m_gravity;
}

inline bool b2World::IsLocked() const
{
    return (m_flags & e_locked) == e_locked;
}

inline void b2World::SetAutoClearForces(bool flag)
{
    if (flag)
    {
        m_flags |= e_clearForces;
    }
    else
    {
        m_flags &= ~e_clearForces;
    }
}

/// Get the flag that controls automatic clearing of forces after each time step.
inline bool b2World::GetAutoClearForces() const
{
    return (m_flags & e_clearForces) == e_clearForces;
}

#endif
 

---

Box2D was recently updated. I am refollowing a tutorial and noticed this, too. However, if you view the header file, you'll notice the new default constructor only takes the gravity. Remove the sleep variable.

YourVariable = new b2World(gravity);

Will fix that. I don't know what the other person is doing, they appear to be redefining the actual header... which is a good idea for engines that are pure skeletons, but Box2D isn't a skeleton engine, its functions are fully defined, don't try to rewrite it as a fix, unless you know your physics

---

You need to either provide a default constructor for b2World, or you need to initialize world in the initializer list:

bc_Game::bc_Game() :world(gravity, sleep)
{
}

This would also require gravity and sleep to be pre-constructed though.