Question

我正在编写一个小游戏。你可以射击小子弹，当击中物体时它们会消失。问题是当我销毁尸体（直接或首先将它们存储到数组中）时，我在CreateFixture（）函数中得到错误以创建新的子弹。代码：

-(void)tick:(ccTime)deltaTime {
    if(canShoot)
        [self performPistol];
    [self updatePositions:deltaTime];
    [self collisionDetection];
}


-(void)updatePositions:(ccTime)deltaTime {
    int32 velocityIterations = 8;
    int32 positionIterations = 1;
    world->Step(deltaTime, velocityIterations, positionIterations);
    for(id object in _objectsToDelete) {
        b2Body *body = (b2Body*)[object pointerValue];
        [self removeChild:((CCSprite*)body->GetUserData()) cleanup:YES];
        world->DestroyBody((b2Body*)[object pointerValue]);
    }
    [_objectsToDelete removeAllObjects];
}

-(void)collisionDetection {
    for (b2Contact* c = world->GetContactList(); c; c = c->GetNext()) {
        b2Body *a = c->GetFixtureA()->GetBody();
        b2Body *b = c->GetFixtureB()->GetBody();
        CCSprite *aSprite = (CCSprite*)a->GetUserData();
        CCSprite *bSprite = (CCSprite*)b->GetUserData();
        if([[aSprite class] isSubclassOfClass:[Bullet class]]) {
            if([[bSprite class] isSubclassOfClass:[Zombie class]]) {
                Zombie *myZombie = (Zombie*)bSprite;
                myZombie.hp -= [(Bullet*)aSprite strength];
                if(myZombie.hp <= 0) {
                    [_objectsToDelete addObject:[NSValue valueWithPointer:b]];
                }
            }
            [_objectsToDelete addObject:[NSValue valueWithPointer:a]];
        } else if([[bSprite class] isSubclassOfClass:[Bullet class]]) {
            if([[aSprite class] isSubclassOfClass:[Zombie class]]) {
                Zombie *myZombie = (Zombie*)aSprite;
                myZombie.hp -= [(Bullet*)bSprite strength];
                if(myZombie.hp <= 0) {
                    [_objectsToDelete addObject:[NSValue valueWithPointer:a]];
                }
            }
            [_objectsToDelete addObject:[NSValue valueWithPointer:b]];
        }

    }
}

-(void)performPistol {
    float degreeRadians = _myRotation*(M_PI/180.0);
    CGPoint normalVector = ccp(cosf(degreeRadians),sinf(degreeRadians));
    Bullet *bullet = [[Bullet alloc] initWithFile:@"bullet_line.png"];
    bullet.strength = 1;
    bullet.position = ccp(_myPosition.x+(normalVector.x*25.0),_myPosition.y+(normalVector.y*25.0));
    bullet.rotation = _myRotation*(-1);

    b2BodyDef bodyDef;
    bodyDef.type = b2_dynamicBody;
    bodyDef.bullet = true;

    bodyDef.position.Set(bullet.position.x/PTM_RATIO, bullet.position.y/PTM_RATIO);
    bodyDef.userData = bullet;
    b2Body *body = world->CreateBody(&bodyDef);

    // Define another box shape for our dynamic body.
    b2PolygonShape box;
    box.SetAsBox(6.25/PTM_RATIO, 0.5/PTM_RATIO);

    // Define the dynamic body fixture.
    b2FixtureDef fixtureDef;
    fixtureDef.shape = &box;    
    fixtureDef.density = 1.0f;
    fixtureDef.friction = 0.3f;
    fixtureDef.filter.categoryBits = MASK_PLAYER;
    fixtureDef.filter.maskBits = MASK_ENEMY | MASK_WALL;
    body->CreateFixture(&fixtureDef);
    body->SetLinearVelocity(b2Vec2(normalVector.x*50.0,normalVector.y*50.0));
    body->SetTransform(body->GetPosition(), CC_DEGREES_TO_RADIANS(-bullet.rotation));
    [self addChild:bullet];
}

为什么CreateFixture（）函数中存在错误。结束并不总是相同的有时一个断言错误有时是一个exc_bad_access？

感谢

Box2D / Cocos2D：CreateFixture中的错误

0 个答案: