使用osg画一个四棱锥

好的，以下是使用 OpenSceneGraph (OSG) 画一个四棱锥的示例代码：

#include <osgViewer/Viewer>
#include <osg/Geometry>
#include <osg/Geode>

int main()
{
    // 创建一个场景图
    osg::ref_ptr<osg::Group> root = new osg::Group();

    // 创建四棱锥的顶点坐标
    osg::ref_ptr<osg::Vec3Array> vertices = new osg::Vec3Array;
    vertices->push_back(osg::Vec3(0, 0, 0));
    vertices->push_back(osg::Vec3(1, 0, 0));
    vertices->push_back(osg::Vec3(0.5, 0.866, 0));
    vertices->push_back(osg::Vec3(0.5, 0.433, 0.75));
    vertices->push_back(osg::Vec3(0.5, -0.433, 0.75));

    // 创建四棱锥的面
    osg::ref_ptr<osg::DrawElementsUInt> base = new osg::DrawElementsUInt(osg::PrimitiveSet::QUADS, 0);
    base->push_back(0);
    base->push_back(1);
    base->push_back(2);
    base->push_back(0);

    osg::ref_ptr<osg::DrawElementsUInt> side1 = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    side1->push_back(0);
    side1->push_back(2);
    side1->push_back(3);

    osg::ref_ptr<osg::DrawElementsUInt> side2 = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    side2->push_back(0);
    side2->push_back(3);
    side2->push_back(4);

    osg::ref_ptr<osg::DrawElementsUInt> side3 = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
    side3->push_back(0);
    side3->push_back(4);
    side3->push_back(2);

    // 创建几何体并添加顶点和面
    osg::ref_ptr<osg::Geometry> geometry = new osg::Geometry();
    geometry->setVertexArray(vertices.get());
    geometry->addPrimitiveSet(base.get());
    geometry->addPrimitiveSet(side1.get());
    geometry->addPrimitiveSet(side2.get());
    geometry->addPrimitiveSet(side3.get());

    // 创建几何体节点并添加到场景图中
    osg::ref_ptr<osg::Geode> geode = new osg::Geode();
    geode->addDrawable(geometry.get());
    root->addChild(geode.get());

    // 创建查看器并设置场景图
    osgViewer::Viewer viewer;
    viewer.setSceneData(root.get());
    viewer.run();

    return 0;
}

这段代码会创建一个四棱锥的几何体，并将其添加到场景图中。你可以使用 OSG 的查看器工具查看生成的四棱锥。