# File vtk/gtk/GtkGLExtVTKRenderWindow.rb, line 500
  def Zoom(x,y)
    if @CurrentRenderer

      renderer = @CurrentRenderer
      camera = @CurrentCamera

      zoomFactor = 1.02**(0.5*(@LastY - y))
      @CurrentZoom = @CurrentZoom * zoomFactor

      if camera.GetParallelProjection
        parallelScale = camera.GetParallelScale/zoomFactor
        camera.SetParallelScale(parallelScale)
      else
        camera.Dolly(zoomFactor)
        renderer.ResetCameraClippingRange
      end

      @LastX = x
      @LastY = y

      self.Render
    end
  end