第二天（五）osgViewer::Viewer::readConfiguration（）

目前的框架如下：

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）待续

                ]

advance(simulationTime);

eventTraversal();

updateTraversal();

renderingTraversals();

}

 

下一步就是继续

                    //建立视口和相关的线程

                     ->osgViewer::Viewer::realize()

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

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

                    ->（3）待续

去掉焦点窗口，获得上下文数组以后，如果图形上下文数组为空，则说明仿真系统还没有合适的显示平台，需要建立一个缺省的图形上下文设备，并再次执行获取上下文数组，如果还是没有得到任何图形上下文的话，则只能退出程序了。

现在看看如何创建缺省图形上下文设备。

首先读取环境变量OSG_CONFIG_FILE是否存在，如果这个环境变量存在，则用osgDB::readObjectFile函数读入文件，并用cfg插件进行解析，如果成功，则调用osgViewer::Viewer::take()函数，使用配置信息设置当前的视景器。即
bool osgViewer::Viewer::readConfiguration(const std::string& filename)

这个函数只适合于单视窗，不适合多视窗。

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()->待续

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

                    ->(4)待续

                ]

advance(simulationTime);

eventTraversal();

updateTraversal();

renderingTraversals();

}