OSG创建基本图形

直接上代码：

osg::ref_ptr<osg::Node> createSimple() {
    osg::ref_ptr<osg::Geode> geode = new osg::Geode;
    osg::ref_ptr<osg::Geometry> geo = new osg::Geometry;

    //申请一些顶点
    osg::ref_ptr<osg::Vec3Array> vers = new osg::Vec3Array;
    geo->setVertexArray(vers.get());
#if 1
    geo->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::LINE_LOOP, 0, 4));//创建一个线圈
#else
    geo->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS, 0, 4));//创建一个正方形
#endif


    //设置顶点
    vers->push_back(osg::Vec3(-1.5, 0.0, -1.5));
    vers->push_back(osg::Vec3(1.5, 0.0, -1.5));
    vers->push_back(osg::Vec3(1.5, 0.0, 1.5));
    vers->push_back(osg::Vec3(-1.5, 0.0, 1.5));

    //申请颜色
    osg::ref_ptr<osg::Vec4Array> color = new osg::Vec4Array();
    color->push_back(osg::Vec4(1.0, 0.0, 0.0, 0.5));
    color->push_back(osg::Vec4(0.0, 1.0, 0.0, 0.5));
    color->push_back(osg::Vec4(0.0, 0.0, 1.0, 0.5));
    color->push_back(osg::Vec4(1.0, 1.0, 0.0, 0.5));

    //设置颜色
    geo->setColorArray(color.get());
    geo->setColorBinding(osg::Geometry::AttributeBinding::BIND_PER_VERTEX);//设置颜色绑定

    //设置法线，正对屏幕的时候最亮
    osg::ref_ptr<osg::Vec3Array> norm = new osg::Vec3Array;
    geo->setNormalArray(norm);
    geo->setNormalBinding(osg::Geometry::AttributeBinding::BIND_OVERALL);
    norm->push_back(osg::Vec3(0.0, -1.0, 0.0));

    //打开透明度
    geo->getOrCreateStateSet()->setMode(GL_BLEND, osg::StateAttribute::ON);

    //设置线宽
    osg::ref_ptr<osg::LineWidth> w = new osg::LineWidth;
    w->setWidth(5.0);
    geo->getOrCreateStateSet()->setAttributeAndModes(w.get(), osg::StateAttribute::ON);

    geode->addDrawable(geo.get());

    return geode;
}

int main(int argc, char** argv) {
    for (int i = 0; i < argc; i++) {
        printf(argv[i]);
        printf("\n");
    }

    osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer();


    viewer->addEventHandler(new osgViewer::WindowSizeHandler);
    viewer->addEventHandler(new osgViewer::StatsHandler);

    osg::ref_ptr<osg::Group> root = new osg::Group;
    root->addChild(osgDB::readNodeFile("xyz.osgt")); 
    root->addChild(createSimple());

    viewer->setSceneData(root);

    viewer->realize();
    viewer->run();

    return 0;
}

运行效果：