C ++ - Undefined reference to `vtable

Question

C ++ - Undefined reference to `vtable

I was wondering why I get this error: undefined reference to `vtable for BaseRenderer '

I tried searching, but didn't seem to understand this. I tried to get rid of the virtual function by deleting the constructor, etc.

My baserenderer.h

class BaseRenderer : public Renderer
{
 Q_OBJECT

    public:
        BaseRenderer();
        BaseRenderer(QWidget *parent);
        void paintGL();

        virtual ~BaseRenderer();

 public slots:
  void loadDialog();

 signals:

    protected:
        Mesh loadMesh(string fileName);

    private:

        OBJParser objParser;
        Mesh baseTerrain;

};

My BaseRenderer.cpp

BaseRenderer::BaseRenderer()              <------ Error leads me here
{
}

BaseRenderer::BaseRenderer(QWidget *parent) : Renderer(parent)
{

}

BaseRenderer::~BaseRenderer()
{
    //dtor
}