改变锚点时，同过计算偏移量修正position从而保持CCNode在屏幕上的位置不变
1 void CLayer::change_anchorpoint(CCNode* node,CCPoint newpt) 2 { 3 float dx, dy, diffx, diffy, height, width; 4 width = node->getContentSize().width; 5 height = node->getContentSize().height; 6 7 diffx = (newpt.x - node->getAnchorPoint().x)*width; 8 diffy = (newpt.y - node->getAnchorPoint().y)*height; 9 node->setPositionX(node->getPositionX() + diffx); 10 node->setPositionY(node->getPositionY() + diffy); 11 node->setAnchorPoint(newpt); 12 }
newpt为新锚点的位置