本课NeHe教程主要是使用了OpenGL中的显示列表。OpenGL的显示列表是加速OpenGL性能的一种重要的手段。OpenGl的几何体绘制方法主要包括立即模式、顶点数组、显示列表和VBO。在OSG中显示列表是大部分OSG程序所使用的默认绘制优化行为，因此不需要我们去像OpenGL那样进行设置。
首先创建整个场景，本课中我使用了OSG中预定义的几种基本形体，(osg::Box)来绘制立方体
[cpp] view plain copy osg::Node* buildScene() { osg::Group *root = new osg::Group; for (int yloop=1;yloop<6;yloop++) { osg::Group *cubeGroup = new osg::Group; for (int xloop=0;xloop<yloop;xloop++) { osg::MatrixTransform *posMT = new osg::MatrixTransform; posMT->setMatrix(osg::Matrix::translate(1.4f+(float(xloop)*2.8f)-(float(yloop)*1.4f),((6.0f-float(yloop))*2.4f)-7.0f,-20.0f)); cubeGroup->addChild(posMT); osg::MatrixTransform *rotXMT = new osg::MatrixTransform; rotXMT->setName("XRotMT"); posMT->addChild(rotXMT); XRotCallback* xrot = new XRotCallback(osg::DegreesToRadians(45.0f-(2.0f*yloop))); rotXMT->setUpdateCallback(xrot); osg::MatrixTransform *rotYMT = new osg::MatrixTransform; rotXMT->addChild(rotYMT); rotYMT->setName("YRotMT"); YRotCallback* yrot = new YRotCallback(osg::DegreesToRadians(45.0f)); rotYMT->setUpdateCallback(yrot); osg::Geode *cube = createCube(yloop-1); rotYMT->addChild(cube); } root->addChild(cubeGroup); } return root; } 参照NeHe教程中平移量进行(glTranslate对应一个osg::MatrixTransform)，对于每一个几何体叶节点，通过不同的颜色索引值创建它
[cpp] view plain copy osg::Geode* createCube(int colorIndex) { osg::Image *textureImage = osgDB::readImageFile("Data/Cube.bmp"); osg::Texture2D *texture2D = new osg::Texture2D; texture2D->setImage(textureImage); texture2D->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR); texture2D->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR); osg::ShapeDrawable *sd = new osg::ShapeDrawable(new osg::Box(osg::Vec3(0, 0, 0), 2)); sd->setColor(osg::Vec4d(boxcol[colorIndex][0], boxcol[colorIndex][1], boxcol[colorIndex][2], 1)); osg::Geode *cubeGeode = new osg::Geode; cubeGeode->addDrawable(sd); cubeGeode->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture2D); return cubeGeode; } 可以看到场景中对每一个MatrixTransform均设置了UpdateCallback，为的是通过键盘对它们进行操作。首先先通过名字找到所有这些节点
[cpp] view plain copy class FindNamedNodeVisitor : public osg::NodeVisitor { public: FindNamedNodeVisitor(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.push_back(&node); } traverse(node); } std::string _name; std::vector<osg::Node*> _foundNode; }; 在EventHandler交互类中进行设置如下：
[cpp] view plain copy if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Left) { FindNamedNodeVisitor fnnv("YRotMT"); root->accept(fnnv); for (unsigned i = 0; i < fnnv._foundNode.size(); ++i) { yrot = dynamic_cast<YRotCallback*>(fnnv._foundNode.at(i)->getUpdateCallback()); if (yrot) { yrot->setAngle(yrot->getAngle() - osg::DegreesToRadians(2.0)); } } } 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 <osgDB/ReadFile> #include <osg/Texture2D> #include <osg/ShapeDrawable> #include <osg/NodeVisitor> static GLfloat boxcol[5][3]= { {1.0f,0.0f,0.0f},{1.0f,0.5f,0.0f},{1.0f,1.0f,0.0f},{0.0f,1.0f,0.0f},{0.0f,1.0f,1.0f} }; // //RotCallback class XRotCallback : public osg::NodeCallback { public: XRotCallback(double angle) : _angle(angle){} virtual void operator()(osg::Node* node, osg::NodeVisitor* nv) { if (dynamic_cast<osg::MatrixTransform*>(node)) { osg::MatrixTransform *rot = dynamic_cast<osg::MatrixTransform*>(node); rot->setMatrix(osg::Matrix::rotate(_angle, osg::X_AXIS)); } traverse(node, nv); } void setAngle(double angle) { _angle = angle; } double getAngle() const { return _angle; } double _angle; }; class YRotCallback : public osg::NodeCallback { public: YRotCallback(double angle) : _angle(angle){} virtual void operator()(osg::Node* node, osg::NodeVisitor* nv) { if (dynamic_cast<osg::MatrixTransform*>(node)) { osg::MatrixTransform *rot = dynamic_cast<osg::MatrixTransform*>(node); rot->setMatrix(osg::Matrix::rotate(_angle, osg::Y_AXIS)); } traverse(node, nv); } void setAngle(double angle) { _angle = angle; } double getAngle() const { return _angle; } double _angle; }; //End // class FindNamedNodeVisitor : public osg::NodeVisitor { public: FindNamedNodeVisitor(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.push_back(&node); } traverse(node); } std::string _name; std::vector<osg::Node*> _foundNode; }; // //EventHandler 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): { XRotCallback *xrot; YRotCallback *yrot; if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Left) { FindNamedNodeVisitor fnnv("YRotMT"); root->accept(fnnv); for (unsigned i = 0; i < fnnv._foundNode.size(); ++i) { yrot = dynamic_cast<YRotCallback*>(fnnv._foundNode.at(i)->getUpdateCallback()); if (yrot) { yrot->setAngle(yrot->getAngle() - osg::DegreesToRadians(2.0)); } } } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Right) { FindNamedNodeVisitor fnnv("YRotMT"); root->accept(fnnv); for (unsigned i = 0; i < fnnv._foundNode.size(); ++i) { yrot = dynamic_cast<YRotCallback*>(fnnv._foundNode.at(i)->getUpdateCallback()); if (yrot) { yrot->setAngle(yrot->getAngle() + osg::DegreesToRadians(2.0)); } } } if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Up) { FindNamedNodeVisitor fnnv("XRotMT"); root->accept(fnnv); for (unsigned i = 0; i < fnnv._foundNode.size(); ++i) { xrot = dynamic_cast<XRotCallback*>(fnnv._foundNode.at(i)->getUpdateCallback()); if (xrot) { xrot->setAngle(xrot->getAngle() - osg::DegreesToRadians(2.0)); } } } if (ea.getKey()== osgGA::GUIEventAdapter::KEY_Down) { FindNamedNodeVisitor fnnv("XRotMT"); root->accept(fnnv); for (unsigned i = 0; i < fnnv._foundNode.size(); ++i) { xrot = dynamic_cast<XRotCallback*>(fnnv._foundNode.at(i)->getUpdateCallback()); if (xrot) { xrot->setAngle(xrot->getAngle() + osg::DegreesToRadians(2.0)); } } } } default: break; } return false; } }; //End // 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)); 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::Geode* createCube(int colorIndex) { osg::Image *textureImage = osgDB::readImageFile("Data/Cube.bmp"); osg::Texture2D *texture2D = new osg::Texture2D; texture2D->setImage(textureImage); texture2D->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR); texture2D->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR); osg::ShapeDrawable *sd = new osg::ShapeDrawable(new osg::Box(osg::Vec3(0, 0, 0), 2)); sd->setColor(osg::Vec4d(boxcol[colorIndex][0], boxcol[colorIndex][1], boxcol[colorIndex][2], 1)); osg::Geode *cubeGeode = new osg::Geode; cubeGeode->addDrawable(sd); cubeGeode->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture2D); return cubeGeode; } osg::Node* buildScene() { osg::Group *root = new osg::Group; for (int yloop=1;yloop<6;yloop++) { osg::Group *cubeGroup = new osg::Group; for (int xloop=0;xloop<yloop;xloop++) { osg::MatrixTransform *posMT = new osg::MatrixTransform; posMT->setMatrix(osg::Matrix::translate(1.4f+(float(xloop)*2.8f)-(float(yloop)*1.4f),((6.0f-float(yloop))*2.4f)-7.0f,-20.0f)); cubeGroup->addChild(posMT); osg::MatrixTransform *rotXMT = new osg::MatrixTransform; rotXMT->setName("XRotMT"); posMT->addChild(rotXMT); XRotCallback* xrot = new XRotCallback(osg::DegreesToRadians(45.0f-(2.0f*yloop))); rotXMT->setUpdateCallback(xrot); osg::MatrixTransform *rotYMT = new osg::MatrixTransform; rotXMT->addChild(rotYMT); rotYMT->setName("YRotMT"); YRotCallback* yrot = new YRotCallback(osg::DegreesToRadians(45.0f)); rotYMT->setUpdateCallback(yrot); osg::Geode *cube = createCube(yloop-1); rotYMT->addChild(cube); } root->addChild(cubeGroup); } 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(); }
