OpenSceneGraph实现的NeHe OpenGL教程 - 第十四课
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本节课实现在场景中绘制3D的轮廓字体,实现方式和第十三课中类似,只不过我们需要使用的是osgText库中的三维字体类osgText::Text3D
首先同样需要绘制osgText,将它加到场景的叶节点之中
- osg::Group *root = new osg::Group;
-
- osg::MatrixTransform *moveMT = new osg::MatrixTransform;
- moveMT->setMatrix(osg::Matrix::translate(-2, 0, -10));
- root->addChild(moveMT);
-
- osg::MatrixTransform *rotX = new osg::MatrixTransform;
- rotX->setUpdateCallback(new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::X_AXIS, 0.5));
- osg::MatrixTransform *rotY = new osg::MatrixTransform;
- rotY->setUpdateCallback(new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::Y_AXIS, 0.4));
- osg::MatrixTransform *rotZ = new osg::MatrixTransform;
- rotZ->setUpdateCallback(new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::Z_AXIS, 0.3));
-
- moveMT->addChild(rotX);
- rotX->addChild(rotY);
- rotY->addChild(rotZ);
-
- osg::Geode *fontGeode = new osg::Geode;
-
- osgText::Text3D *text = new osgText::Text3D;
- text->setCharacterSize(0.8f);
- text->setCharacterDepth(0.2f);
- text->setUpdateCallback(new FontColorCallback);
- text->setText("OpenGL NeHe");
- text->setFont("fonts/arial.ttf");
- fontGeode->addDrawable(text);
-
- rotZ->addChild(fontGeode);
-
- return root;
唯一不同的是我们需要设置字体的"厚度",通过setCharacterDepth函数实现,为了简便起见,我们使用AnimationPathCallback来实现旋转为了实现动态的颜色改变效果,我们使用和上一课一样的方式
- class FontColorCallback : public osg::Drawable::UpdateCallback
- {
- public:
-
- virtual void update(osg::NodeVisitor*, osg::Drawable* drawable)
- {
- if (dynamic_cast<osgText::Text3D*>(drawable))
- {
- osgText::Text3D *text = dynamic_cast<osgText::Text3D*>(drawable);
- text->setColor(osg::Vec4(1.0f*float(cos(rot/20.0f)),1.0f*float(sin(rot/25.0f)),1.0f-0.5f*float(cos(rot/17.0f)), 1));
-
- std::stringstream os;
- std::string str;
- os.precision(2);
- os << std::fixed << "NeHe - " << rot;
- str = os.str();
-
- text->setText(str);
- rot+=0.5f;
- }
- }
- };
最后编译运行程序附:本课源码(源码中可能存在错误和不足,仅供参考)
- #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 <osgText/Text>
- #include <osgText/Text3D>
-
- #include <osg/AnimationPath>
-
- #include <iostream>
- #include <sstream>
-
- float rot = 0.0;
-
- class FontColorCallback : public osg::Drawable::UpdateCallback
- {
- public:
-
- virtual void update(osg::NodeVisitor*, osg::Drawable* drawable)
- {
- if (dynamic_cast<osgText::Text3D*>(drawable))
- {
- osgText::Text3D *text = dynamic_cast<osgText::Text3D*>(drawable);
- text->setColor(osg::Vec4(1.0f*float(cos(rot/20.0f)),1.0f*float(sin(rot/25.0f)),1.0f-0.5f*float(cos(rot/17.0f)), 1));
-
- std::stringstream os;
- std::string str;
- os.precision(2);
- os << std::fixed << "NeHe - " << rot;
- str = os.str();
-
- text->setText(str);
- rot+=0.5f;
- }
- }
- };
-
-
-
- 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 );
-
- 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::MatrixTransform *moveMT = new osg::MatrixTransform;
- moveMT->setMatrix(osg::Matrix::translate(-2, 0, -10));
- root->addChild(moveMT);
-
- osg::MatrixTransform *rotX = new osg::MatrixTransform;
- rotX->setUpdateCallback(new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::X_AXIS, 0.5));
- osg::MatrixTransform *rotY = new osg::MatrixTransform;
- rotY->setUpdateCallback(new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::Y_AXIS, 0.4));
- osg::MatrixTransform *rotZ = new osg::MatrixTransform;
- rotZ->setUpdateCallback(new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::Z_AXIS, 0.3));
-
- moveMT->addChild(rotX);
- rotX->addChild(rotY);
- rotY->addChild(rotZ);
-
- osg::Geode *fontGeode = new osg::Geode;
-
- osgText::Text3D *text = new osgText::Text3D;
- text->setCharacterSize(0.8f);
- text->setCharacterDepth(0.2f);
- text->setUpdateCallback(new FontColorCallback);
- text->setText("OpenGL NeHe");
- text->setFont("fonts/arial.ttf");
- fontGeode->addDrawable(text);
-
- rotZ->addChild(fontGeode);
-
- 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();
- }
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