code: def _check_pyopengl_3D():
      
      global USE_TEX_3D
      USE_TEX_3D = True
      try:
          import OpenGL.GL as _gl
      except ImportError:
          raise ImportError('PyOpenGL is required for 3D texture support')
      return _gl
docs: Helper to ensure users have OpenGL for 3D texture support (for now)