VTK 光线追踪代码

以下是使用VTK的ray tracing模块实现光线追踪的示例代码：

#include <vtkSmartPointer.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkCamera.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkLight.h>
#include <vtkLightCollection.h>
#include <vtkSmartPointer.h>
#include <vtkRendererCollection.h>

int main(int, char *[])
{
  // 创建一个球体
  vtkSmartPointer<vtkSphereSource> sphereSource = vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(1.0);
  sphereSource->Update();

  // 创建一个mapper
  vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(sphereSource->GetOutputPort());

  // 创建一个actor
  vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(1.0, 0.0, 0.0); // 设置球体颜色

  // 创建渲染器和相机
  vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(actor);
  renderer->SetBackground(0.0, 0.0, 0.0); // 设置背景色为黑色
  vtkSmartPointer<vtkCamera> camera = vtkSmartPointer<vtkCamera>::New();
  camera->SetPosition(0.0, 0.0, 5.0); // 设置相机位置
  camera->SetFocalPoint(0.0, 0.0, 0.0); // 设置相机的焦点
  renderer->SetActiveCamera(camera);

  // 创建灯光
  vtkSmartPointer<vtkLight> light = vtkSmartPointer<vtkLight>::New();
  light->SetLightTypeToSceneLight();
  light->SetPosition(0, 0, 10); // 设置灯光位置
  light->SetFocalPoint(0, 0, 0); // 设置灯光聚焦点
  light->SetDiffuseColor(1.0, 1.0, 1.0); // 设置灯光颜色
  light->SetAmbientColor(1.0, 1.0, 1.0);
  light->SetSpecularColor(1.0, 1.0, 1.0);
  vtkSmartPointer<vtkLightCollection> lights = renderer->GetLights();
  lights->AddItem(light);

  // 创建渲染窗口和交互器
  vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // 开始渲染
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

此代码将创建一个红色的球体，并在其上方添加一个灯光。在渲染时，ray tracing模块将使用光线追踪算法计算光线与球体的相交，并生成真实的光照效果。