/**
该示例定义了两个 vtkLight 对象,一个为绿色光,位置在(0,0,1),焦点对着相机的焦点;
另一个为蓝色光,位置在(0.0-1),焦点也是对着相机的焦点,
最后调用 vtkRenderer 的方法AddLight0将两个灯光对象加入到染场景中。
因为 Renderer 里可以有多个灯光,所以VTK提供的接口是AddLight()而不是SetLight()
**/
vtkSmartPointer<vtkLight> myLight = vtkSmartPointer<vtkLight>::New();
myLight->SetColor(0,1,0);
myLight->SetPosition(0,0,1);
myLight->SetFocalPoint(renderer->GetActiveCamera()->GetFocalPoint());
renderer->AddLight(myLight);
vtkSmartPointer<vtkLight> myLight2 = vtkSmartPointer<vtkLight>::New();
myLight2->SetColor(0, 0, 1);
myLight2->SetPosition(0, 0, -1);
myLight2->SetFocalPoint(renderer->GetActiveCamera()->GetFocalPoint());
renderer->AddLight(myLight2);