void RenderBin::drawImplementation(osg::RenderInfo& renderInfo,RenderLeaf*& previous)
{
osg::State& state = *renderInfo.getState();
// osg::notify(osg::NOTICE)<<"begin RenderBin::drawImplementation "<<className()<<" sortMode "<<getSortMode()<<std::endl;
unsigned int numToPop = (previous ? StateGraph::numToPop(previous->_parent) : 0);
if (numToPop>1) --numToPop;
unsigned int insertStateSetPosition = state.getStateSetStackSize() - numToPop;//自动插入一个_stateset用于处理透明渲染,见构造函数
if (_stateset.valid())
{
state.insertStateSet(insertStateSetPosition, _stateset.get());
}
// draw first set of draw bins.
RenderBinList::iterator rbitr; //_bins在生成的时候可以自动排序(由于是map类型),所以先执行->first小于0的
for(rbitr = _bins.begin();
rbitr!=_bins.end() && rbitr->first<0;
++rbitr)
{
rbitr->second->draw(renderInfo,previous); //由于是递归调用,所以不断地向下层遍历,一直递归调用到最低层的renderBin
}
// draw fine grained ordering.
for(RenderLeafList::iterator rlitr= _renderLeafList.begin(); //渲染叶,在渲染前排序的时候,由_stateGraphList复制过来,同时清空
rlitr!= _renderLeafList.end(); //
++rlitr)
{
RenderLeaf* rl = *rlitr;
rl->render(renderInfo,previous); //_stateGraphList,如果是深度排序,则把所有的_stateGraphiList里面的渲染叶完考备过来
previous = rl;
}
bool draw_forward = true; //(_sortMode!=SORT_BY_STATE) || (state.getFrameStamp()->getFrameNumber() % 2)==0;
// draw coarse grained ordering.
if (draw_forward)//如果不是从后到前排序,则不需要从_stateGraphlist里面拷备出渲染叶,
{
for(StateGraphList::iterator oitr=_stateGraphList.begin();
oitr!=_stateGraphList.end();
++oitr)
{
for(StateGraph::LeafList::iterator dw_itr = (*oitr)->_leaves.begin();
dw_itr != (*oitr)->_leaves.end();
++dw_itr)
{
RenderLeaf* rl = dw_itr->get();
rl->render(renderInfo,previous);
previous = rl;
}
}
}
else
{
for(StateGraphList::reverse_iterator oitr=_stateGraphList.rbegin();
oitr!=_stateGraphList.rend();
++oitr)
{
for(StateGraph::LeafList::iterator dw_itr = (*oitr)->_leaves.begin();
dw_itr != (*oitr)->_leaves.end();
++dw_itr)
{
RenderLeaf* rl = dw_itr->get();
rl->render(renderInfo,previous);
previous = rl;
}
}
}
// draw post bins.
for(;
rbitr!=_bins.end();
++rbitr)
{
rbitr->second->draw(renderInfo,previous); //渲染编号大于0的
}
if (_stateset.valid())
{
state.removeStateSet(insertStateSetPosition);
// state.apply();
}
// osg::notify(osg::NOTICE)<<"end RenderBin::drawImplementation "<<className()<<std::endl;
//以上函数递归调用,先渲染状态树最底层的,并且编号小于o的,接着是大于o的,然后渲染倒数第二层的编号小于o,接着是倒数第二层编号大于o的
//渲染树和状态树的相对层数相同,相同层数的drawable放在相同层数的bin里面
}