第二天（八）osg::Object* readObjectFile(const std::string& filename,const ReaderWriter::Options* options)

本文链接：https://blog.youkuaiyun.com/directx3d_beginner/article/details/106169204

目前流程是:

osgViewer::viewBase:: frame()

{

viewerInit();[

//创建帧事件，并将漫游器与事件和视口相关联

-> osgViewer::Viewer::ViewerInit()

-> osgViewer::View::Init();

->(1)osgGA::EventQueue::createEvent();

(2)osgGA::MatrixManipulator::Init();

->(2.1)各种漫游器::init()

]

isRealized()；[

//获取图形上下文数组。再遍历上下文数组，只要有一个准备好就Ok

-> osgViewer::Viewer::isRealized()；

->(1)osgViewer::Viewer::getContexts().

->(1.1)osg::camera::getGraphicsContext()

->(1.2)osg::View::getNumSlaves()

->(1.3)osg::View::getSlave()

->(1.4)LessGraphicsContext()->osg::GraphicContext::getTraits()

->(2)osg::GraphicContext::isRealized()

->(2.1)->（1）

->(2.2)osg::GraphicsContext::isRealized()

->osg::GraphicsContext::isRealizedImplementation()

->(2.2.1)osgViewer::GraphicsWindow::isRealizedImplementation()

->(2.2.1.1)osgViewer:: GraphicsWindowWin32 ::isRealizedImplementation()

->(2.2.1.2) osgViewer::GraphicsWindowEmbedded ::isRealizedImplementation()

->(2.2.2)osgViewer::PixelBufferWin32::isRealizedImplementation()

]

realize(); [

//建立视口和相关的线程

->osgViewer::Viewer::realize()

->(1) osgViewer::Viewer::setCameraWithFocus()

->(2)osgViewer::Viewer::getContexts()

->（3）osgViewer::Viewer::readConfiguration(）

->(3.1)osgDB::readObjectFile(const std::string& filename)

->(3.1.1)osg::Object* readObjectFile(const std::string& filename,const ReaderWriter::Options* options);

->(3.1.2)osgDB::Registry* osgDB::Registry::instance(bool erase);

->(3.1.3)ReaderWriter::Options* osgDB::getOptions();

->(3.2)osgViewer::Viewer::take()

->(4)待续

]

advance(simulationTime);

eventTraversal();

updateTraversal();

renderingTraversals();

}

接下来分析，从文件中读取osg::object*指针，有效则获取osg::object指针，无效则报错

Object* osgDB::readObjectFile(const std::string& filename,const ReaderWriter::Options* options)
{
ReaderWriter::ReadResult rr = Registry::instance()->readObject(filename,options);
if (rr.validObject()) return rr.takeObject();
if (rr.error()) notify(WARN) << rr.message() << std::endl;
return NULL;
}

涉及到了几个函数

ReaderWriter::ReadResult readObject(const std::string& fileName,const ReaderWriter::Options* options)；

ReaderWriter::ReadResult::validObject（）

ReaderWriter::ReadResult::takeObject()

ReaderWriter::ReadResult::error()

ReaderWriter::ReadResult::message()