Qt使用osg画四棱锥

您可以使用Qt与OpenSceneGraph（OSG）库来绘制四棱锥。下面是一个简单的示例代码，可以在Qt窗口中显示四棱锥：

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

osg::ref_ptr<osg::Node> createPyramid()
{
    osg::ref_ptr<osg::Vec3Array> vertices = new osg::Vec3Array;
    vertices->push_back(osg::Vec3(-1.0f, -1.0f, 0.0f));
    vertices->push_back(osg::Vec3(1.0f, -1.0f, 0.0f));
    vertices->push_back(osg::Vec3(1.0f, 1.0f, 0.0f));
    vertices->push_back(osg::Vec3(-1.0f, 1.0f, 0.0f));
    vertices->push_back(osg::Vec3(0.0f, 0.0f, 1.0f));

    osg::ref_ptr<osg::DrawElementsUInt> pyramidIndices = new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 18);
    pyramidIndices->push_back(0); pyramidIndices->push_back(1); pyramidIndices->push_back(4);
    pyramidIndices->push_back(1); pyramidIndices->push_back(2); pyramidIndices->push_back(4);
    pyramidIndices->push_back(2); pyramidIndices->push_back(3); pyramidIndices->push_back(4);
    pyramidIndices->push_back(3); pyramidIndices->push_back(0); pyramidIndices->push_back(4);
    pyramidIndices->push_back(0); pyramidIndices->push_back(1); pyramidIndices->push_back(2);
    pyramidIndices->push_back(0); pyramidIndices->push_back(2); pyramidIndices->push_back(3);

    osg::ref_ptr<osg::Geometry> pyramidGeometry = new osg::Geometry;
    pyramidGeometry->setVertexArray(vertices.get());
    pyramidGeometry->addPrimitiveSet(pyramidIndices.get());

    osg::ref_ptr<osg::Geode> pyramidGeode = new osg::Geode;
    pyramidGeode->addDrawable(pyramidGeometry.get());

    return pyramidGeode.get();
}

int main(int argc, char** argv)
{
    osgViewer::Viewer viewer;
    viewer.setSceneData(createPyramid().get());
    viewer.setUpViewInWindow(100, 100, 640, 480);
    viewer.realize();
    while(!viewer.done())
    {
        viewer.frame();
    }
    return 0;
}

在这个例子中，我们首先定义了四棱锥的顶点和索引，并将它们放入osg::Geometry对象中。然后将这个Geometry对象添加到一个osg::Geode节点中，并将这个Geode节点作为场景图的根节点。最后，我们创建了一个OSG查看器，用于在Qt窗口中显示场景图。

您可以根据需要调整顶点和索引，以创建自己的四棱锥。