这节课将在第四课的基础上进行扩展，创建3D物体。我们将三角形变为3D的三棱锥形，把四边形变为立方体。同时三棱锥沿Y轴旋转，四边形沿着（1,1,1）方向旋转。
本课与第二课十分类似，只需要多绘制几个面即可，三棱锥的绘制代码如下
[cpp] view plain copy osg::Geometry *triangleGeometry = new osg::Geometry; osg::Vec3Array *triangleVertexArray = new osg::Vec3Array; for (unsigned i = 0; i < sizeof(TriangleVertices); ++i) { triangleVertexArray->push_back(osg::Vec3(TriangleVertices[i][0], TriangleVertices[i][1], TriangleVertices[i][2])); } triangleGeometry->setVertexArray(triangleVertexArray); osg::Vec4Array *triangleColorArray = new osg::Vec4Array; for (unsigned i = 0; i < sizeof(TriangleColors); ++i) { triangleColorArray->push_back(osg::Vec4(TriangleColors[i][0], TriangleColors[i][1], TriangleColors[i][2], 1.0f)); } triangleGeometry->setColorArray(triangleColorArray); triangleGeometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX); triangleGeometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::TRIANGLES, 0, 12)); 在这里需要注意在DrawArrays类的构造函数需要将第三个参数修改为所有Vertex的总数，即12个
以下是立方体的绘制代码
[cpp] view plain copy osg::Geometry *quadGeometry = new osg::Geometry; osg::Vec3Array *quadVertexArray = new osg::Vec3Array; for (unsigned i = 0; i < sizeof(QuadVertices); ++i) { quadVertexArray->push_back(osg::Vec3(QuadVertices[i][0], QuadVertices[i][1], QuadVertices[i][2])); } quadGeometry->setVertexArray(quadVertexArray); int first = 0; for (unsigned i = 0; i < 6; ++i) { osg::DrawArrays *vertexIndices = new osg::DrawArrays(osg::PrimitiveSet::QUADS, first, 4); first += 4; quadGeometry->addPrimitiveSet(vertexIndices); } [cpp] view plain copy osg::Vec4Array *quadColorArray = new osg::Vec4Array; for (unsigned i = 0; i < sizeof(QuadColors); ++i) { quadColorArray->push_back(osg::Vec4(QuadColors[i][0], QuadColors[i][1], QuadColors[i][2], 1.0f)); } quadGeometry->setColorArray(quadColorArray); quadGeometry->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE_SET); 注意到颜色绑定的方式是每个PrimitiveSet绑定一次，总共需要6个颜色值。
此处如果使用DrawArrayLengths那么绑定的方式不能设置为BIND_PER_PRIMITIVE_SET，因为它只是一个PrimitiveSet，只会绑定第一个颜色值。
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/AnimationPath> float TriangleVertices[][3] = { {0.0f, 1.0f, 0.0f}, {-1.0f,-1.0f, 1.0f}, { 1.0f,-1.0f, 1.0f}, {0.0f, 1.0f, 0.0f}, {1.0f,-1.0f, 1.0f}, { 1.0f,-1.0f, -1.0f}, {0.0f, 1.0f, 0.0f},{1.0f,-1.0f, -1.0f},{ -1.0f,-1.0f, -1.0f}, {0.0f, 1.0f, 0.0f}, {-1.0f,-1.0f, -1.0f}, { -1.0f,-1.0f, 1.0f} }; float TriangleColors[][3] = { { 1.0f, 0.0f, 0.0f}, { 0.0f,1.0f,0.0f}, { 0.0f,0.0f,1.0f}, { 1.0f, 0.0f, 0.0f}, { 0.0f,0.0f,1.0f}, { 0.0f,1.0f,0.0f}, { 1.0f, 0.0f, 0.0f}, { 0.0f,1.0f,0.0f}, { 0.0f,0.0f,1.0f}, { 1.0f,0.0f,0.0f}, { 0.0f,0.0f,1.0f},{ 0.0f,1.0f,0.0f} }; float QuadVertices[][3] = { {1.0f, 1.0f,-1.0f}, // Top Right Of The Quad (Top) {-1.0f, 1.0f,-1.0f}, // Top Left Of The Quad (Top) {-1.0f, 1.0f, 1.0f}, // Bottom Left Of The Quad (Top) { 1.0f, 1.0f, 1.0f}, // Bottom Right Of The Quad (Top)}; { 1.0f,-1.0f, 1.0f}, // Top Right Of The Quad {Bottom} {-1.0f,-1.0f, 1.0f}, // Top Left Of The Quad {Bottom} {-1.0f,-1.0f,-1.0f}, // Bottom Left Of The Quad {Bottom} { 1.0f,-1.0f,-1.0f}, // Bottom Right Of The Quad {Bottom} { 1.0f, 1.0f, 1.0f}, // Top Right Of The Quad {Front} {-1.0f, 1.0f, 1.0f}, // Top Left Of The Quad {Front} {-1.0f,-1.0f, 1.0f}, // Bottom Left Of The Quad {Front} { 1.0f,-1.0f, 1.0f}, // Bottom Right Of The Quad {Front} { 1.0f,-1.0f,-1.0f}, // Top Right Of The Quad {Back} {-1.0f,-1.0f,-1.0f}, // Top Left Of The Quad {Back} {-1.0f, 1.0f,-1.0f}, // Bottom Left Of The Quad {Back} { 1.0f, 1.0f,-1.0f}, // Bottom Right Of The Quad {Back} {-1.0f, 1.0f, 1.0f}, // Top Right Of The Quad {Left} {-1.0f, 1.0f,-1.0f}, // Top Left Of The Quad {Left} {-1.0f,-1.0f,-1.0f}, // Bottom Left Of The Quad {Left} {-1.0f,-1.0f, 1.0f}, // Bottom Right Of The Quad {Left} { 1.0f, 1.0f,-1.0f}, // Top Right Of The Quad {Right} { 1.0f, 1.0f, 1.0f}, // Top Left Of The Quad {Right} { 1.0f,-1.0f, 1.0f}, // Bottom Left Of The Quad {Right} { 1.0f,-1.0f,-1.0f} // Bottom Right Of The Quad {Right} }; const float QuadColors[][3] ={{ 0.0f,1.0f,0.0f },{ 1.0f,0.5f,0.0f },{ 1.0f, 0.0f, 0.0f }, { 1.0f, 1.0f, 0.0f },{ 0.0f, 0.0f, 1.0f }, { 1.0f, 0.0f, 1.0f } }; 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 *triangleMT = new osg::MatrixTransform; triangleMT->setMatrix(osg::Matrix::translate(-1.5, 0.0, -6.0)); osg::AnimationPathCallback *triangleAnimationCallback = new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::Y_AXIS, 2); osg::MatrixTransform *triangleRotMT = new osg::MatrixTransform; triangleRotMT->setUpdateCallback(triangleAnimationCallback); osg::Geometry *triangleGeometry = new osg::Geometry; osg::Vec3Array *triangleVertexArray = new osg::Vec3Array; for (unsigned i = 0; i < sizeof(TriangleVertices); ++i) { triangleVertexArray->push_back(osg::Vec3(TriangleVertices[i][0], TriangleVertices[i][1], TriangleVertices[i][2])); } triangleGeometry->setVertexArray(triangleVertexArray); osg::Vec4Array *triangleColorArray = new osg::Vec4Array; for (unsigned i = 0; i < sizeof(TriangleColors); ++i) { triangleColorArray->push_back(osg::Vec4(TriangleColors[i][0], TriangleColors[i][1], TriangleColors[i][2], 1.0f)); } triangleGeometry->setColorArray(triangleColorArray); triangleGeometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX); triangleGeometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::TRIANGLES, 0, 12)); osg::Geode *triangleGeode = new osg::Geode; triangleGeode->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF); triangleGeode->addDrawable(triangleGeometry); triangleRotMT->addChild(triangleGeode); triangleMT->addChild(triangleRotMT); //四边形部分 osg::MatrixTransform *quadMT = new osg::MatrixTransform; quadMT->setMatrix(osg::Matrix::translate(1.5, 0.0, -6.0)); osg::AnimationPathCallback *quadAnimationCallback = new osg::AnimationPathCallback(osg::Vec3d(0, 0, 0), osg::Vec3(1, 1, 1), 2.5); osg::MatrixTransform *quadRotMT = new osg::MatrixTransform; quadRotMT->setUpdateCallback(quadAnimationCallback); osg::Geometry *quadGeometry = new osg::Geometry; osg::Vec3Array *quadVertexArray = new osg::Vec3Array; for (unsigned i = 0; i < sizeof(QuadVertices); ++i) { quadVertexArray->push_back(osg::Vec3(QuadVertices[i][0], QuadVertices[i][1], QuadVertices[i][2])); } quadGeometry->setVertexArray(quadVertexArray); int first = 0; for (unsigned i = 0; i < 6; ++i) { osg::DrawArrays *vertexIndices = new osg::DrawArrays(osg::PrimitiveSet::QUADS, first, 4); first += 4; quadGeometry->addPrimitiveSet(vertexIndices); } // //osg::DrawArrayLengths是一个PrimitiveSet,绑定颜色方式为BIND_PER_PRIMITIVE_SET //会出失败，只能显示为一种颜色 //osg::DrawArrayLengths *v = new osg::DrawArrayLengths(osg::PrimitiveSet::QUADS, 0); //for (unsigned i = 0; i < 6; ++i) //{ // v->push_back(4); //} //quadGeometry->addPrimitiveSet(v); osg::Vec4Array *quadColorArray = new osg::Vec4Array; for (unsigned i = 0; i < sizeof(QuadColors); ++i) { quadColorArray->push_back(osg::Vec4(QuadColors[i][0], QuadColors[i][1], QuadColors[i][2], 1.0f)); } quadGeometry->setColorArray(quadColorArray); quadGeometry->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE_SET); osg::Geode *quadGeode = new osg::Geode; quadGeode->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF); quadGeode->addDrawable(quadGeometry); quadRotMT->addChild(quadGeode); quadMT->addChild(quadRotMT); root->addChild(triangleMT); 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(); }
