Box2D的身体旋转

Question

我有一个姿态recignizer，我需要旋转体：

- (void) rotate:(UIGestureRecognizer*)recognizer node:(CCNode*)node 
{ 
    b2Body *body = (b2Body*)[node.parent userData]; 
    UIRotationGestureRecognizer* rotate = (UIRotationGestureRecognizer*)recognizer; 
    b2Vec2 pos = body->GetPosition(); 
    body->SetTransform(pos, (- rotate.rotation)); 

} 

offcorse，当我开始旋转时，它从零角度开始。 * 但是如何从当前角度继续旋转？ *我不能只添加rotate.rotation tu当前角度：这种方法每一次都会调用，角度是从开始时的手势开始计算的。跟踪实际的当前角度（不anctive手势的角度），将是一个非常艰巨的任务，我认为

Answer 1

我找到了解决办法： 我检查的手势的状态（有一个begining状态）：

- (void) rotate:(UIGestureRecognizer*)recognizer node:(CCNode*)node 
{ 
    b2Body *body = (b2Body*)[node.parent userData]; 
    UIRotationGestureRecognizer* rotate = (UIRotationGestureRecognizer*)recognizer; 
    if (rotate.state == UIGestureRecognizerStateBegan) 
    { 
     baseAngle = body->GetAngle(); 
    } 
    b2Vec2 pos = body->GetPosition(); 
    body->SetTransform(pos, (baseAngle - rotate.rotation)); 

}