0

コード内の 2 つのスプライト間にweldJoint を作成し (以下の update メソッドを参照)、mouseJoint が解放されたときにスプライトの正確な位置を返すメソッドも作成しました。スプライトの現在位置を spritePositionRelease 値と比較し、y 値が同じで x 値が異なる場合は、weldJoint を破棄したいと考えています。助けてください。

spritePositionRelease:

- (CGPoint)spritePositionRelease    {

for(b2Body *b = mouseJoint->GetBodyB(); b; b=b->GetNext())    {
    if (b->GetUserData() != NULL)
    {
        CCSprite *mySprite = (CCSprite*)b->GetUserData();
        if (mySprite.tag == 1) {
            mySprite.position = CGPointMake( b->GetPosition().x * PTM_RATIO, b->GetPosition().y * PTM_RATIO);
            CGPoint spritePosition = mySprite.position;
            CCLOG(@"the sprite position is x:%0.2f , y:%0.2f", spritePosition.x, spritePosition.y);

            return spritePosition;

        }
    }
}
}

ccTouchesEnded:

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{

if (mouseJoint)
{
    [self spritePositionRelease];

    world->DestroyJoint(mouseJoint);
    mouseJoint = NULL;
}
}

アップデート：

-(void) update: (ccTime) dt
{
//It is recommended that a fixed time step is used with Box2D for stability
//of the simulation, however, we are using a variable time step here.
//You need to make an informed choice, the following URL is useful
//http://gafferongames.com/game-physics/fix-your-timestep/

int32 velocityIterations = 8;
int32 positionIterations = 1;

// Instruct the world to perform a single step of simulation. It is
// generally best to keep the time step and iterations fixed.
world->Step(dt, velocityIterations, positionIterations);

// using the iterator pos over the set
std::set<BodyPair *>::iterator pos;

for(pos = bodiesForJoints.begin(); pos != bodiesForJoints.end(); ++pos)
{
    b2WeldJoint         *weldJoint;
    b2WeldJointDef      weldJointDef;

    BodyPair            *bodyPair = *pos;
    b2Body              *bodyA = bodyPair->bodyA;
    b2Body              *bodyB = bodyPair->bodyB;

    weldJointDef.Initialize(bodyA,
                            bodyB,
                            bodyA->GetWorldCenter());

    weldJointDef.collideConnected = false;
    weldJoint = (b2WeldJoint*) world->CreateJoint(&weldJointDef);

    // Free the structure we allocated earlier.
    free(bodyPair);

    // Remove the entry from the set.
    bodiesForJoints.erase(pos);
}

}
4

1 に答える 1

0

mouseJoint->GetBodyB() が常に正しいボディを返すと確信していますか? たぶん、mouseJoint->GetBodyA() を確認する必要がありますか?

とにかく、あなたのチェックは非常に簡単です：

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{

if (mouseJoint)
{
   CGPoint releasePoint = [self spritePositionRelease];
   CGPoint touchPoint = [[touches anyObject] locationInView:[[touches anyObject] view]];
   if((releasePoint.y==touchPoint.y) &&(releasePoint.x!=touchPoint.x))
   {
//Destroy weld joint
   }
    world->DestroyJoint(mouseJoint);
    mouseJoint = NULL;
}
}
于 2012-08-15T05:40:07.557 に答える