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I have Ball class which is derived from PhysicsObject class. In the following method I am getting a Ball instance from a void pointer and checking if its of type PhysicsObject. When I call the collidingWith method, it is not being called in the Ball class object. What am I doing wrong here?

UPDATE I have added an sscce at the bottom. Please refer that.

CODE

void Levels::BeginContact(b2Contact *contact) {
    b2Fixture *fixtureA = contact->GetFixtureA();
    b2Fixture *fixtureB = contact->GetFixtureB();
    void *objA = fixtureA->GetUserData();
    void *objB = fixtureB->GetUserData();

    PhysicsObject* physicsObjA = reinterpret_cast<PhysicsObject*>(objA);
    PhysicsObject* physicsObjB = reinterpret_cast<PhysicsObject*>(objB);
    if ((physicsObjA != 0) && (physicsObjB != 0)) {
        physicsObjA->collidingWith(physicsObjB);    //not working
        physicsObjB->collidingWith(physicsObjA);
    }
}

PHYSICSOBJECT

#ifndef PHYSICSOBJECT_H_
#define PHYSICSOBJECT_H_

class PhysicsObject {
public:
    PhysicsObject();
    virtual ~PhysicsObject();

    virtual void collidingWith(PhysicsObject *obj) = 0;
};

#endif /* PHYSICSOBJECT_H_ */

Ball.h 

#ifndef BALL_H_
#define BALL_H_

#include "Box2D/Box2d.h"
#include "cocos2d.h"
#include "PhysicsObject.h"

class Ball : public PhysicsObject {
public:
    //other methods
    void collidingWith(PhysicsObject *obj);
};

#endif /* BALL_H_ */

Ball.cpp

void Ball::collidingWith(PhysicsObject *obj) {
    CCLOG("Ball::collidingWith"); //this method is not being called
}
 //other methods

Ball::Ball() {
    //other code
    b2FixtureDef ballShapeDef;
    ballShapeDef.userData = this;
    //other code
}

UPDATE I have 3-4 other classes which are being derived from PhysicsObject just like Ball, those I havent mentioned here, but the common code is same.

UPDATE SSCCE
In main.cpp 's foo() getting error at baseObjA->collidingWith(baseObjA);

Base Class

class Base
{
public:
    Base(void);
    virtual ~Base(void);
    virtual void collidingWith(Base *obj) = 0;
};

Another Base Class 

class AnotherBase
{
public:
    AnotherBase(void);
    ~AnotherBase(void);
    virtual void foo();
};

Derived Class Header 

#include "Base.h"
#include "AnotherBase.h"
class Derived :
    public AnotherBase, Base
{
public:
    Derived(void);
    ~Derived(void);
    void collidingWith(Base *obj);
};

Derived Class Implementation 

#include "Derived.h"

void Derived::collidingWith(Base *obj) {
    printf("Ball::collidingWith");
}

main.cpp 

#include "Derived.h"

void myFoo(void* userData);
int _tmain(int argc, _TCHAR* argv[])
{
    Derived *derived = new Derived();
    void* userData = derived;
    myFoo(userData);
    return 0;
}

void myFoo(void* userData) 
{
    Base* baseObjA = reinterpret_cast<Base*>(userData); 
    if (baseObjA != 0) {
        baseObjA->collidingWith(baseObjA);// Error here
    }
}
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1 に答える 1

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box2d の void* からのキャストでも、非常によく似た問題が発生しました。

仮想メソッドと同様にreinterpret_cast、エラーの原因のようです。collidingWith(メソッドが仮想でない場合は、問題なく呼び出すことができるはずです)。

私はこれを行うように修正しました：

void* data; // You know it's type is Base

Base* base = static_cast<Base*>(data);
Derived* derived = dynamic_cast<Derived*>(base);

derived->collidingWith();
于 2013-05-12T17:31:50.273 に答える