box2d CreateFixture with b2FixtureDef给出了纯虚函数调用

Question

我有这个代码,在行中给我运行时错误:

  body->CreateFixture(&boxDef) 

我在windows中使用cocos2d-x 2.1.5和box2d 2.2.1

CCSprite *sprite = CCSprite::create(imageName.c_str());
    this->addChild(sprite,1);

    b2BodyDef bodyDef;
    bodyDef.type = isStatic?b2_staticBody:b2_dynamicBody;
    bodyDef.position.Set((position.x+sprite->getContentSize().width/2.0f)/PTM_RATIO,
                         (position.y+sprite->getContentSize().height/2.0f)/PTM_RATIO);
    bodyDef.angle = CC_DEGREES_TO_RADIANS(rotation);
    bodyDef.userData = sprite;
    b2Body *body = world->CreateBody(&bodyDef);

    b2FixtureDef boxDef;
    if (isCircle)
    {
        b2CircleShape circle;
        circle.m_radius = sprite->getContentSize().width/2.0f/PTM_RATIO;
        boxDef.shape = &circle;
    }
    else
    {
        b2PolygonShape box;
        box.SetAsBox(sprite->getContentSize().width/2.0f/PTM_RATIO, sprite->getContentSize().height/2.0f/PTM_RATIO);
        boxDef.shape = &box;
    }

    if (isEnemy)
    {
        boxDef.userData = (void*)1;
        enemies->insert(body);

    }

    boxDef.density = 0.5f;
    body->CreateFixture(&boxDef)  //<-- HERE IS THE RUN TIME ERROR 

;

当我调试box2d代码即时到达方法中的b2Fixture.cpp:

void b2Fixture::Create(b2BlockAllocator* allocator, b2Body* body, const b2FixtureDef* def)

在线:

m_shape = def->shape->Clone(allocator);

得到运行时错误:

R6025纯虚函数调用

Answer 1

棘手的一个.我自己碰到了几次.它与变量范围有关.

boxDef.shape是问题所在.您可以在if/else块中将形状创建为局部变量,然后将它们分配给boxDef.一旦执行离开if/else块作用域,那么这些局部变量将是垃圾.boxDef.shape现在指向释放的内存.

解决方案是通过在if/else块之前移动圆形和框形状声明来保持形状变量的范围.