如何添加不规则实体到world中？

Cocos2d-x
#1

HelloWorldScene的demo中添加的是一个方型的sprite,如果是圆的咋加？不规则图形又咋加？不胜感激
-(void)addSprite:(CGPoint)p
{
CCSprite * m_sprite = ;
;
b2BodyDef bodyDef;
bodyDef.type = b2_dynamicBody;
bodyDef.position.Set(p.x/PTM_RATIO,p.y/PTM_RATIO);
bodyDef.userData = m_sprite;
b2Body * body = world->CreateBody(&bodyDef);

b2PolygonShape dynamicBox;
dynamicBox.SetAsBox(0.5f,0.5f);	
b2FixtureDef fixtureDef;
fixtureDef.shape = &dynamicBox;
fixtureDef.density = 1.0f;
fixtureDef.friction = 0.3f;
body->CreateFixture(&fixtureDef);

}

#2

没人顶，自己顶起。
b2PolygonShape dynamicBox;
dynamicBox.SetAsBox(1.0f,1.0f);
//定义body的形状为规则的正方形。

//b2PolygonShape dynamicBox;
// int num = 4;
// b2Vec2 vertices] = { //以下四组数据需按逆时针顺序排列。（0，0）点为m_sprite的position的中心点。
// b2Vec2(64.0f / PTM_RATIO, -64.0f / PTM_R

#3

以上是解决方法，已做过验证。大家可以放心用。