[virtual]
Copy this object.
Reimplemented from FX::FXGLObject.
Reimplemented in FX::FXGLCone, FX::FXGLCube, FX::FXGLCylinder, FX::FXGLSphere, FX::FXGLTriangleMesh, FX::FXGLVertices, and FX::FXGLCircle.