图像在OSG中随着旋转而消失

我有一个简单的OSG程序，它制作一个x，y轴并随机化该轴内的点。目的是，这将导致为激光扫描数据制作3D查看器。（我知道它以前做过，但我们需要它超轻量级）。这是代码：

#include <osg/Node>
#include <osg/Group>
#include <osg/Geode>
#include <osg/Geometry>
#include <osg/Texture2D>
#include <osgDB/ReadFile> 
#include <osgViewer/Viewer>
#include <osg/PositionAttitudeTransform>
#include <osgGA/TrackballManipulator>
#include <time.h>
#include <cstdlib>
void addAxis(osg::ref_ptr<osg::Group> root) {

//ADD Y-Axis
osg::ref_ptr<osg::Geode> lineGeode = new osg::Geode();
osg::ref_ptr<osg::Geometry> yAxis = new osg::Geometry(), xAxis = new osg::Geometry();
lineGeode->addDrawable(yAxis);
lineGeode->addDrawable(xAxis);
root->addChild(lineGeode);

osg::ref_ptr<osg::Vec3Array> lineVertices = new osg::Vec3Array;
lineVertices->push_back( osg::Vec3( 0, 0, 0) );
lineVertices->push_back( osg::Vec3(0, 10, 0) );

yAxis->setVertexArray( lineVertices );
osg::ref_ptr<osg::DrawElementsUInt> lineBase =
    new osg::DrawElementsUInt(osg::PrimitiveSet::LINES, 0);
lineBase->push_back(1);
lineBase->push_back(0);
yAxis->addPrimitiveSet(lineBase);

osg::ref_ptr<osg::Vec4Array> colors = new osg::Vec4Array;
colors->push_back(osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f) ); //index 0 red
yAxis->setColorArray(colors);
yAxis->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE);

//ADD X Axis
lineVertices = new osg::Vec3Array;
lineVertices->push_back( osg::Vec3( 0, 0, 0) );
lineVertices->push_back( osg::Vec3(10, 0, 0) );

xAxis->setVertexArray( lineVertices );
lineBase =
    new osg::DrawElementsUInt(osg::PrimitiveSet::LINES, 0);
lineBase->push_back(1);
lineBase->push_back(0);
xAxis->addPrimitiveSet(lineBase);

colors = new osg::Vec4Array;
colors->push_back(osg::Vec4(0.0f, 0.0f, 0.0f, 1.0f) ); //index 0 red
xAxis->setColorArray(colors);
xAxis->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE);
}
void addPoint(osg::ref_ptr<osg::Group> root, std::vector<double> pointIn) {
 osg::ref_ptr<osg::Geode> pointGeode = new osg::Geode();
osg::ref_ptr<osg::Geometry> pointGeometry = new osg::Geometry();

pointGeode->addDrawable(pointGeometry);
root->addChild(pointGeode);
osg::ref_ptr<osg::Vec3Array> point = new osg::Vec3Array;
point->push_back( osg::Vec3( pointIn[0], pointIn[1], pointIn[2]) );
pointGeometry->setVertexArray( point );
osg::ref_ptr<osg::DrawElementsUInt> points =
    new osg::DrawElementsUInt(osg::PrimitiveSet::POINTS, 0);
points->push_back(0);
points->push_back(2);
points->push_back(1);
pointGeometry->addPrimitiveSet(points);

osg::ref_ptr<osg::Vec4Array> colors = new osg::Vec4Array;
colors->push_back(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f) ); 
 pointGeometry->setColorArray(colors);
    pointGeometry->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE);
}

int main()
{
osgViewer::Viewer viewer;
osg::ref_ptr<osg::Group> root = new osg::Group();
addAxis(root);

std::vector<double> point;
for (int i = 0; i < 3; i++)
   point.push_back(0);
srand(time(NULL));
root->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
viewer.setSceneData( root );
viewer.setCameraManipulator(new osgGA::TrackballManipulator());
viewer.realize();
int count = 0;
while( !viewer.done() )
{
    if (count == 200) {
    point[0] = (double)rand()*10.0/(double)INT_MAX;
    point[1] = (double)rand()*10.0/(double)INT_MAX;
    count = 0;
    }
    count++;
    addPoint(root, point);
    viewer.frame();

}
return 0;
}

此代码有效，它将生成一个 10 个单位长的 x/y 轴，并开始在该轴内生成随机点。但是，问题是当我在OSG查看器中旋转图像时，整个图像通常会消失。有时它可以通过旋转回到你开始的地方来恢复，但更多的时候它会永远消失。

有没有人知道为什么会发生这种情况？