简介

这节课在第七课的基础上修改了部分代码，用来在场景中显示圆球、圆柱、圆锥等二次几何体。在osg中定义了一些基本的几何体，主要有如下几种：

Fig1. osg内置定义的几何体类型

实现

在本课中通过切换空格键实现几何体的切换，在osg中开关节点osg::Switch用在这里再合适不过了，它可以切换不同的子节点进行显示

我们定义如下：

[cpp]  view plain  copy   //       //新增代码，使用开关节点管理       g_Switch = new osg::Switch;          //添加立方体       osg::Geode *box = new osg::Geode;       osg::ShapeDrawable *boxDrawable = new osg::ShapeDrawable;       osg::Box *boxShape = new osg::Box(osg::Vec3(0, 0,0), 2);       boxDrawable->setShape(boxShape);       box->addDrawable(boxDrawable);       g_Switch->addChild(box);          //添加圆柱体       osg::Geode *cylinder = new osg::Geode;       osg::ShapeDrawable *cylinderDrawable = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0,0,0), 0.5, 2.0));       cylinder->addDrawable(cylinderDrawable);       g_Switch->addChild(cylinder);          //添加圆盘       osg::Geode *disk = new osg::Geode;       osg::ShapeDrawable *diskDrawable = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0,0,0), 0.5, 0.001));       disk->addDrawable(diskDrawable);       g_Switch->addChild(disk);          //添加圆球       osg::Geode *sphere = new osg::Geode;       osg::ShapeDrawable *sphereDrawable = new osg::ShapeDrawable(new osg::Sphere(osg::Vec3(0,0,0), 1.3));       sphere->addDrawable(sphereDrawable);       g_Switch->addChild(sphere);          //添加圆锥       osg::Geode *cone = new osg::Geode;       osg::ShapeDrawable *coneDrawable = new osg::ShapeDrawable(new osg::Cone(osg::Vec3(0,0,0), 0.5, 2));       cone->addDrawable(coneDrawable);       g_Switch->addChild(cone);          g_Switch->setSingleChildOn(0);   //   使用setSingleChildOn来让其中一个显示，我们让立方体先显示，所以用的是它的索引值0

在键盘交互处理中同样调用这个函数来切换：

[cpp]  view plain  copy   if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Space)   {       static int index = 0;       g_Switch->setSingleChildOn(++index % 5);   }   其余部分和第七课代码是一样的，编译运行程序：

附：本课源码(源码中可能存在错误和不足，仅供参考)

[cpp]  view plain  copy   #include "../osgNeHe.h"      #include <QtCore/QTimer>   #include <QtGui/QApplication>   #include <QtGui/QVBoxLayout>      #include <osgViewer/Viewer>   #include <osgDB/ReadFile>   #include <osgQt/GraphicsWindowQt>      #include <osg/MatrixTransform>   #include <osg/NodeVisitor>   #include <osg/Texture2D>      #include <osgGA/GUIEventAdapter>      #include <osg/Light>   #include <osg/LightModel>   #include <osg/LightSource>      #include <osg/ShapeDrawable>   #include <osg/Switch>         //   //开关节点   osg::Switch     *g_Switch;      //   //FindFirstNamedNodeVisitor用来遍历寻找与指定名称相同的节点      class FindFirstNamedNodeVisitor : public osg::NodeVisitor   {   public:       FindFirstNamedNodeVisitor(const std::string& name):         osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ALL_CHILDREN),             _name(name), _foundNode(NULL) {}            virtual void apply(osg::Node& node)         {             if (node.getName()==_name)             {                 _foundNode = &node;                 return;             }             traverse(node);         }            std::string _name;         osg::Node *_foundNode;   };      //   //RotateCallback      class RotateCallback : public osg::NodeCallback   {      public:       RotateCallback(osg::Vec3d rotateAxis, double rotateSpeed) :          osg::NodeCallback(),             _rotateAxis(rotateAxis),              _rotateSpeed(rotateSpeed),             _rotateAngle(0.0)         {             //Nop         }            void setRotateSpeed(double speed)         {             _rotateSpeed = speed;         }            double getRotateSpeed() const         {             return _rotateSpeed;         }            virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)         {             osg::MatrixTransform *currentMT = dynamic_cast<osg::MatrixTransform*>(node);             if (currentMT)             {                 //获取当前的平移位置                 osg::Vec3d currentTranslate = currentMT->getMatrix().getTrans();                 osg::Matrix newMatrix = osg::Matrix::rotate(_rotateAngle, _rotateAxis) * osg::Matrix::translate(currentTranslate);                 currentMT->setMatrix(newMatrix);                 _rotateAngle += _rotateSpeed;             }                traverse(node, nv);         }         private:       osg::Vec3d _rotateAxis;         //旋转轴       double        _rotateSpeed;     //旋转速度       double        _rotateAngle;     //当前旋转的角度   };               //      class ManipulatorSceneHandler : public osgGA::GUIEventHandler   {   public:       ManipulatorSceneHandler()       {       }          virtual bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)       {           osgViewer::Viewer *viewer = dynamic_cast<osgViewer::Viewer*>(&aa);           if (!viewer)               return false;           if (!viewer->getSceneData())               return false;           if (ea.getHandled())                return false;              osg::Group *root = viewer->getSceneData()->asGroup();              switch(ea.getEventType())           {           case(osgGA::GUIEventAdapter::KEYDOWN):               {                   if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Left)                   {                       FindFirstNamedNodeVisitor fnv("yRotMT");                       root->accept(fnv);                          osg::Node *mtNode = fnv._foundNode;                       osg::MatrixTransform *yRotMT = dynamic_cast<osg::MatrixTransform*>(mtNode);                       if (!yRotMT)                           return false;                          RotateCallback *rotCallback = dynamic_cast<RotateCallback*>(yRotMT->getUpdateCallback());                          if (!rotCallback)                           return false;                          double speed = rotCallback->getRotateSpeed();                       speed += 0.02;                       rotCallback->setRotateSpeed(speed);                      }                      if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Right)                   {                       FindFirstNamedNodeVisitor fnv("yRotMT");                       root->accept(fnv);                          osg::Node *mtNode = fnv._foundNode;                       osg::MatrixTransform *yRotMT = dynamic_cast<osg::MatrixTransform*>(mtNode);                       if (!yRotMT)                           return false;                          RotateCallback *rotCallback = dynamic_cast<RotateCallback*>(yRotMT->getUpdateCallback());                          if (!rotCallback)                           return false;                          double speed = rotCallback->getRotateSpeed();                       speed -= 0.02;                       rotCallback->setRotateSpeed(speed);                   }                      if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Up)                   {                       FindFirstNamedNodeVisitor fnv("xRotMT");                       root->accept(fnv);                          osg::Node *mtNode = fnv._foundNode;                       osg::MatrixTransform *xRotMT = dynamic_cast<osg::MatrixTransform*>(mtNode);                       if (!xRotMT)                           return false;                          RotateCallback *rotCallback = dynamic_cast<RotateCallback*>(xRotMT->getUpdateCallback());                          if (!rotCallback)                           return false;                          double speed = rotCallback->getRotateSpeed();                       speed += 0.02;                       rotCallback->setRotateSpeed(speed);                   }                      if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Down)                   {                       FindFirstNamedNodeVisitor fnv("xRotMT");                       root->accept(fnv);                          osg::Node *mtNode = fnv._foundNode;                       osg::MatrixTransform *xRotMT = dynamic_cast<osg::MatrixTransform*>(mtNode);                       if (!xRotMT)                           return false;                          RotateCallback *rotCallback = dynamic_cast<RotateCallback*>(xRotMT->getUpdateCallback());                          if (!rotCallback)                           return false;                          double speed = rotCallback->getRotateSpeed();                       speed -= 0.02;                       rotCallback->setRotateSpeed(speed);                   }                      if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Page_Up)                   {                          FindFirstNamedNodeVisitor fnv("zoomMT");                       root->accept(fnv);                          osg::Node *mtNode = fnv._foundNode;                       osg::MatrixTransform *zoomMT = dynamic_cast<osg::MatrixTransform*>(mtNode);                       if (!zoomMT)                           return false;                          osg::Vec3 trans = zoomMT->getMatrix().getTrans();                       trans.set(trans.x(), trans.y(), trans.z() + 0.2);                       zoomMT->setMatrix(osg::Matrix::translate(trans));                   }                      if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Page_Down)                   {                       FindFirstNamedNodeVisitor fnv("zoomMT");                       root->accept(fnv);                          osg::Node *mtNode = fnv._foundNode;                       osg::MatrixTransform *zoomMT = dynamic_cast<osg::MatrixTransform*>(mtNode);                       if (!zoomMT)                           return false;                          osg::Vec3 trans = zoomMT->getMatrix().getTrans();                       trans.set(trans.x(), trans.y(), trans.z() - 0.2);                       zoomMT->setMatrix(osg::Matrix::translate(trans));                   }                      if (ea.getKey()== osgGA::GUIEventAdapter::KEY_L)                   {                       static int i = 0;                       if (i % 2 == 0) {                           root->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);                       } else {                           root->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::ON);                       }                       ++i;                   }                      if (ea.getKey()== osgGA::GUIEventAdapter::KEY_F)                   {                       FindFirstNamedNodeVisitor fnv("quadGeode");                       root->accept(fnv);                          osg::Node *mtNode = fnv._foundNode;                       osg::Geode *quadGeode = dynamic_cast<osg::Geode*>(mtNode);                       if (!quadGeode)                           return false;                          osg::Texture2D *texture2D = dynamic_cast<osg::Texture2D*>(quadGeode->getOrCreateStateSet()->getTextureAttribute(0, osg::StateAttribute::TEXTURE));                          static int i = 0;                       if (i % 3 == 0) {                           texture2D->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);                           texture2D->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);                       } else if (i % 3 == 1) {                           texture2D->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);                           texture2D->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR_MIPMAP_NEAREST);                       } else {                           texture2D->setFilter(osg::Texture::MIN_FILTER, osg::Texture::NEAREST);                           texture2D->setFilter(osg::Texture::MAG_FILTER, osg::Texture::NEAREST);                       }                       ++i;                   }                                      if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Space)                   {                       static int index = 0;                       g_Switch->setSingleChildOn(++index % 5);                   }                  }           default: break;           }           return false;       }   };      //      class ViewerWidget : public QWidget, public osgViewer::Viewer   {   public:       ViewerWidget(osg::Node *scene = NULL)       {           QWidget* renderWidget = getRenderWidget( createGraphicsWindow(0,0,100,100), scene);              QVBoxLayout* layout = new QVBoxLayout;           layout->addWidget(renderWidget);           layout->setContentsMargins(0, 0, 0, 1);           setLayout( layout );              connect( &_timer, SIGNAL(timeout()), this, SLOT(update()) );           _timer.start( 10 );       }          QWidget* getRenderWidget( osgQt::GraphicsWindowQt* gw, osg::Node* scene )       {           osg::Camera* camera = this->getCamera();           camera->setGraphicsContext( gw );              const osg::GraphicsContext::Traits* traits = gw->getTraits();              camera->setClearColor( osg::Vec4(0.0, 0.0, 0.0, 1.0) );           camera->setViewport( new osg::Viewport(0, 0, traits->width, traits->height) );           camera->setProjectionMatrixAsPerspective(45.0f, static_cast<double>(traits->width)/static_cast<double>(traits->height), 0.1f, 100.0f );           camera->setViewMatrixAsLookAt(osg::Vec3d(0, 0, 1), osg::Vec3d(0, 0, 0), osg::Vec3d(0, 1, 0));              osg::StateSet* globalStateset = camera->getStateSet();           if (globalStateset)           {               osg::LightModel* lightModel = new osg::LightModel;               lightModel->setAmbientIntensity(osg::Vec4(0,0,0,0));               globalStateset->setAttributeAndModes(lightModel, osg::StateAttribute::ON);           }              this->setSceneData( scene );           this->addEventHandler(new ManipulatorSceneHandler());              return gw->getGLWidget();       }          osgQt::GraphicsWindowQt* createGraphicsWindow( int x, int y, int w, int h, const std::string& name="", bool windowDecoration=false )       {           osg::DisplaySettings* ds = osg::DisplaySettings::instance().get();           osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;           traits->windowName = name;           traits->windowDecoration = windowDecoration;           traits->x = x;           traits->y = y;           traits->width = w;           traits->height = h;           traits->doubleBuffer = true;           traits->alpha = ds->getMinimumNumAlphaBits();           traits->stencil = ds->getMinimumNumStencilBits();           traits->sampleBuffers = ds->getMultiSamples();           traits->samples = ds->getNumMultiSamples();              return new osgQt::GraphicsWindowQt(traits.get());       }          virtual void paintEvent( QPaintEvent* event )       {            frame();        }      protected:          QTimer _timer;   };            osg::Node*  buildScene()   {       osg::Group *root = new osg::Group;          osg::Light* light = new osg::Light();       light->setLightNum(0);       light->setAmbient(osg::Vec4(0.5f, 0.5f, 0.5f, 1.0f));       light->setDiffuse(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f));       light->setPosition(osg::Vec4(0.0f, 0.0f, 2.0f, 1.0f));       osg::LightSource* lightsource = new osg::LightSource();       lightsource->setLight (light);       root->addChild (lightsource);           osg::MatrixTransform *quadMT = new osg::MatrixTransform;       quadMT->setName("zoomMT");       quadMT->setMatrix(osg::Matrix::translate(0.0, 0.0, -5.0));          osg::MatrixTransform *quadXRotMT = new osg::MatrixTransform;       quadXRotMT->setName("xRotMT");       RotateCallback *xRotCallback = new RotateCallback(osg::X_AXIS, 0.0);       quadXRotMT->setUpdateCallback(xRotCallback);             osg::MatrixTransform *quadYRotMT = new osg::MatrixTransform;       quadYRotMT->setName("yRotMT");       RotateCallback *yRotCallback = new RotateCallback(osg::Y_AXIS, 0.0);       quadYRotMT->setUpdateCallback(yRotCallback);      //       //新增代码，使用开关节点管理       g_Switch = new osg::Switch;          //添加立方体       osg::Geode *box = new osg::Geode;       osg::ShapeDrawable *boxDrawable = new osg::ShapeDrawable;       osg::Box *boxShape = new osg::Box(osg::Vec3(0, 0,0), 2);       boxDrawable->setShape(boxShape);       box->addDrawable(boxDrawable);       g_Switch->addChild(box);          //添加圆柱体       osg::Geode *cylinder = new osg::Geode;       osg::ShapeDrawable *cylinderDrawable = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0,0,0), 0.5, 2.0));       cylinder->addDrawable(cylinderDrawable);       g_Switch->addChild(cylinder);          //添加圆盘       osg::Geode *disk = new osg::Geode;       osg::ShapeDrawable *diskDrawable = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0,0,0), 0.5, 0.001));       disk->addDrawable(diskDrawable);       g_Switch->addChild(disk);          //添加圆球       osg::Geode *sphere = new osg::Geode;       osg::ShapeDrawable *sphereDrawable = new osg::ShapeDrawable(new osg::Sphere(osg::Vec3(0,0,0), 1.3));       sphere->addDrawable(sphereDrawable);       g_Switch->addChild(sphere);          //添加圆锥       osg::Geode *cone = new osg::Geode;       osg::ShapeDrawable *coneDrawable = new osg::ShapeDrawable(new osg::Cone(osg::Vec3(0,0,0), 0.5, 2));       cone->addDrawable(coneDrawable);       g_Switch->addChild(cone);          g_Switch->setSingleChildOn(0);   //          osg::Image *textureImage = osgDB::readImageFile("Data/Wall.bmp");       osg::Texture2D *texture2D = new osg::Texture2D;       texture2D->setImage(textureImage);       texture2D->setFilter(osg::Texture::MIN_FILTER, osg::Texture::NEAREST);       texture2D->setFilter(osg::Texture::MAG_FILTER, osg::Texture::NEAREST);       g_Switch->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture2D);          quadYRotMT->addChild(g_Switch);       quadXRotMT->addChild(quadYRotMT);       quadMT->addChild(quadXRotMT);          root->addChild(quadMT);          return root;   }         int main( int argc, char** argv )   {       QApplication app(argc, argv);       ViewerWidget* viewWidget = new ViewerWidget(buildScene());       viewWidget->setGeometry( 100, 100, 640, 480 );       viewWidget->show();       return app.exec();   }