osg的加载osgb数据（一）

osg官方的四个程序：

osgViewer: 四个程序当中用的最多的 OSG 程序，用于查看模型；

osgVersion: 查看osg库版本；

osgArchive: 类似于zip，可将多个.osg模型打包成一个.osga的模型压缩包；

osgConv: 模型格式转换与压缩；

接下来进入正题：

前提条件是假设大家已经完成了osg的编译。

接下来自己新建一个项目，引用之类的基础操作也完成了，开始编写以下代码：

osgt1.cpp

// 1
// 加载osgb的测试
//#include <Windows.h> 添加之后解决一个报错的问题

#include <Windows.h>
#include <osg/Notify>
#include <osg/MatrixTransform>
#include <osg/PositionAttitudeTransform>
#include <osg/Geometry>
#include <osg/Geode>
#include <osg/ref_ptr>

#include <osgDB/ReadFile>
#include <osgUtil/Optimizer>
#include <osgViewer/Viewer>
#include <iostream>

int main(int argc, char** argv)
{
    // use an ArgumentParser object to manage the program arguments. 使用一个参数解析器对象用来管理程序参数
    osg::ArgumentParser arguments(&argc, argv);

    // osg读取一个节点的方法
    // osg::ref_ptr<osg::Node> pNode = osgDB::readNodeFile("cow.osgt");

    // Load default mode 加载默认节点
    osg::ref_ptr<osg::Node> loadedModel = osgDB::readRefNodeFile("E:\\GIS\\广州\\关于树的研究\\OSGB\\data\\Tile_+041_-005\\Tile_+041_-005.osgb");

    // if no model has been successfully loaded report failure.模型没有正确加载的话，报告错误
    if (!loadedModel)
    {
        std::cout << arguments.getApplicationName() << ": No data loaded" << std::endl;
        return 1;
    }/*
    else
    {
        return 0;
    }*/

    // construct the viewer.构造视口
    osgViewer::Viewer viewer;
    // different thread model 不同线程模型
    // enum ThreadingModel
    /*{
            SingleThreaded,单一线程
            CullDrawThreadPerContext,每条内容精选绘制线程 每条内容线程
            ThreadPerContext = CullDrawThreadPerContext,
            DrawThreadPerContext,绘制线程
            CullThreadPerCameraDrawThreadPerContext,每个相机精选线程每条内容绘制线程 每个相机线程
            ThreadPerCamera = CullThreadPerCameraDrawThreadPerContext,
            AutomaticSelection 自动选择
    };*/
    osgViewer::Viewer::ThreadingModel threadingModel = osgViewer::Viewer::AutomaticSelection;
    while (arguments.read("-s")) { threadingModel = osgViewer::Viewer::SingleThreaded; }
    while (arguments.read("-g")) { threadingModel = osgViewer::Viewer::CullDrawThreadPerContext; }
    while (arguments.read("-d")) { threadingModel = osgViewer::Viewer::DrawThreadPerContext; }
    while (arguments.read("-c")) { threadingModel = osgViewer::Viewer::CullThreadPerCameraDrawThreadPerContext; }
    viewer.setThreadingModel(threadingModel);

    int xoffset = 40;
    int yoffset = 40;
    // left window + left slave camera  左窗口+左控制相机
    {
        osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;

        traits->x = xoffset + 0;
        traits->y = yoffset + 0;
        traits->width = 600;
        traits->height = 480;
        traits->windowDecoration = true;
        traits->doubleBuffer = true;
        traits->sharedContext = 0;
        traits->readDISPLAY();
        traits->setUndefinedScreenDetailsToDefaultScreen();

        osg::ref_ptr<osg::GraphicsContext> gc = osg::GraphicsContext::createGraphicsContext(traits.get());

        osg::ref_ptr<osg::Camera> camera = new osg::Camera;
        camera->setGraphicsContext(gc.get());
        camera->setViewport(new osg::Viewport(0, 0, traits->width, traits->height));
        GLenum buffer = traits->doubleBuffer ? GL_BACK : GL_FRONT;
        camera->setDrawBuffer(buffer);
        camera->setReadBuffer(buffer);

        // add this slave camera to the viewer, with a shift left of the projection matrix 将这个从相机添加到查看器中，并将投影矩阵向左移位
        //viewer.addSlave(camera.get(), osg::Matrixd::translate(1.0, 0.0, 0.0), osg::Matrixd());
        viewer.addSlave(camera.get(), osg::Matrixd::translate(0.0, 0.0, 0.0), osg::Matrixd());
    }

     right window + right slave camera 右窗口+右控制相机
    //{
    //    osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
    //    traits->x = xoffset + 600;
    //    traits->y = yoffset + 0;
    //    traits->width = 600;
    //    traits->height = 480;
    //    traits->windowDecoration = true;
    //    traits->doubleBuffer = true;
    //    traits->sharedContext = 0;
    //    traits->readDISPLAY();
    //    traits->setUndefinedScreenDetailsToDefaultScreen();

    //    osg::ref_ptr<osg::GraphicsContext> gc = osg::GraphicsContext::createGraphicsContext(traits.get());

    //    osg::ref_ptr<osg::Camera> camera = new osg::Camera;
    //    camera->setGraphicsContext(gc.get());
    //    camera->setViewport(new osg::Viewport(0, 0, traits->width, traits->height));
    //    GLenum buffer = traits->doubleBuffer ? GL_BACK : GL_FRONT;
    //    camera->setDrawBuffer(buffer);
    //    camera->setReadBuffer(buffer);

    //    // add this slave camera to the viewer, with a shift right of the projection matrix
    //    viewer.addSlave(camera.get(), osg::Matrixd::translate(-1.0, 0.0, 0.0), osg::Matrixd());
    //}

    // optimize the scene graph, remove redundant nodes and state etc.优化场景图，去除冗余节点和状态等
    osgUtil::Optimizer optimizer;
    optimizer.optimize(loadedModel);
    // set the scene to render 渲染场景
    viewer.setSceneData(loadedModel);
    return viewer.run();
}

 运行起来之后效果如下：

单个的osgb文件我们大概了解了，osgb的data全文件呢？ 下篇继续。。。