osg颜色数组加载问题，模型能显示但有警告，并且无法显示颜色

代码为：
osg::ref_ptrosg::Vec4Array c = new osg::Vec4Array;
geom->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
c->push_back(osg::Vec4(1.0, 0.0, 0.0, 1.0));
c->push_back(osg::Vec4(1.0, 0.0, 0.0, 1.0));
c->push_back(osg::Vec4(1.0, 0.0, 0.0, 1.0));

警告为  warning,can't assign attribute binding as no has been array assigned to set binding for
模型能显示出来，但没有颜色，这句警告是说的什么？怎么解决？
win10 64位、VS2015

http://www.ithao123.cn/content-7769215.html

没设置颜色数组啊