box2d 遍历世界中body列表的2种方法

第1种方法，在对 body 列表有删除操作的时候，

采用 while 的遍历方式比较方便(详见box2d白皮书)~

/** Iterate over the bodies in the physics world */

b2Body *node = _world->GetBodyList();

while(node) {

b2Body *b = node;

node = node->GetNext();

if(b->GetUserData() != NULL) {

//Synchronize the AtlasSprites position and rotation with the corresponding(相应的) body

CCSprite *myActor = (CCSprite*)b->GetUserData();

CGPoint position = CGPointMake(b->GetPosition().x*PTM_RATIO, b->GetPosition().y*PTM_RATIO);

if(![MGameScene isPositionOutOfBounds:position]) { //如果没有越界的话，实时更新~

myActor.position = position;

myActor.rotation = -1 *CC_RADIANS_TO_DEGREES(b->GetAngle());

} else {

[_single.gameLayerremoveChild:myActor cleanup:YES];

b->SetUserData(NULL);

b->SetTransform(b2Vec2(7.5f,20.0f), 0.0f); // 设置一个合理的位置储存这些用处已经不大的body们~

b->SetType(b2_staticBody);

}

}

}

第2种方法，适用于不对 body 列表作删除操作的情况

for (b2Body* b =_world->GetBodyList(); b; b = b->GetNext()) {

if (b->GetUserData() !=NULL) {

//Synchronize the AtlasSprites position and rotation with the corresponding body

CCSprite *myActor = (CCSprite*)b->GetUserData();

myActor.position =CGPointMake( b->GetPosition().x *PTM_RATIO, b->GetPosition().y *PTM_RATIO);

myActor.rotation = -1 *CC_RADIANS_TO_DEGREES(b->GetAngle());

}

}