我在我的代码中的两个精灵之间创建了一个weldJoint（参见下面的更新方法），我还创建了一个方法，该方法在释放mouseJoint 时返回精灵的确切位置。我想将精灵的当前位置与 spritePositionRelease 值进行比较，如果 y 值相同而 x 值不同，则销毁weldJoint。请帮忙。
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;
}
}
}
}
ccTouchesEnd:
- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if (mouseJoint)
{
[self spritePositionRelease];
world->DestroyJoint(mouseJoint);
mouseJoint = NULL;
}
}
更新：
-(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);
}
}