osg学习（十六）osg的渲染树构建过程

 

1、osgUtil::SceneView生成渲染树根节点

osgUtil/SceneView.cpp
void SceneView::setDefaults(unsigned int options)
{
    _renderStage = new RenderStage;
    _cullVisitor->setStateGraph(_renderStage .get());
}

2、cull遍历到drawable节点时，添加到渲染树相应部分

osgUtil/CullVisitor.cpp
void CullVisitor::apply(osg::Drawable& drawable)
{
    addDrawableAndDepth(&drawable,&matrix,depth);
}


osgUtil/CullVisitor
inline void CullVisitor::addDrawableAndDepth(osg::Drawable* drawable,osg::RefMatrix* matrix,float depth)
{
    _currentRenderBin->addStateGraph(_currentStateGraph);
    _currentStateGraph->addLeaf(createOrReuseRenderLeaf(drawable,_projectionStack.back().get(),matrix,depth));
}

3、遍历到其它节点比如（Group）时，会移动渲染树的当前节点

osgUtil/CullVisitor
inline void pushStateSet(const osg::StateSet* ss)