日志系统：

日志记录了基于ogre的程序每次运行时的所有事件，系统初始化，状态，性能信息。输出的内容被放在磁盘文件上，文件缺省名是ogre.log。也可以手动显示创建日志系统,这需要在创建Root对象之前实施。

// create an instance of LogManager prior to using LogManager::getSingleton()

LogManager* logMgr = new LogManager;

Log *log = LogManager::getSingleton().createLog("mylog.log", true, true, false);

// third param is not used since we already created a log in the previous step

Root *root = new Root("", "");

可以用Ogre LogManager注册一个Log Listener, 以任何方式重定向log data。可以用这种方式来屏蔽任何日志信息。然后还一个更简单的方法达到上述目的：在实例化Root之前，当实例化一个LogManager后，不调用createLog()方法。

以下是实现日志信息截流的代码片断：

class MyLogListener : public LogListener

{

public:

void write (const String& name, const String& message,

LogMessageLevel level, bool maskDebug)

{

// redirect log output here as needed

};

MyLogListener *myListener = new MyLogListener;

// this is the same as calling LogManager::getSingletonPtr() after the

// LogManager has first been instanced; the same pointer value is returned

LogManager *logMgr = new LogManager;

LogMgr->addListener(myListener);

logMgr->createLog("mylog.log", true, false, true);

logMgr->setLogDetail(LL_NORMAL);

Root *root = new Root("", "", "mylog.log");

Ogre手动初始化

int main(int argc, char *argv[])

{

 // tell Root not to load from any plugins or settings file

 Root *root = new Root("", "");

 // Load feature plugins. Scene managers will register

 // themselves for all scene types they support

 root->loadPlugin("Plugin_CgProgramManager");

 root->loadPlugin("Plugin_OctreeSceneManager");

 // load rendersystem plugin(s). The order is important in that GL

 // should be available on on platforms, while D3D9 would be available

 // only on Windows -- the try/catch will intercept the exception in this

 // case where D3D9 is not available and continue gracefully.

 try {

  root->loadPlugin("RenderSystem_GL");

  root->loadPlugin("RenderSystem_Direct3D9");

 }

 catch (...) {}

 try {

  // We'll simulate the selection of a rendersystem on an arbirtary basis; normally

  // you would have your own code to present the user with options and select the

  // rendersystem on that basis. Since a GUI is beyond the scope of this example, we'll

  // just assume the user selected OpenGL.

  RenderSystemList *rList = root->getAvailableRenderers();

  RenderSystemList::iterator it = rList->begin();

  RenderSystem *rSys = 0;

  while (it != rList->end()) {

   

   rSys = *(it++);

   if (rSys->getName().find("OpenGL")) {

   

    root->setRenderSystem(rSys);

    break;

   }

  }

  // check to see if a render system was selected; if we reached the end of the list

  // without selecting a render system then none was found.

  if (rSys == 0) {

   delete root;

   std::cerr << "No RenderSystem available, exiting..." << std::endl;

   return -1;

  }

  // We can initialize Root here if we want. "false" tells Root NOT to create

  // a render window for us

  root->initialise(false);

  // set up the render window with all default params

  RenderWindow *window = rSys->createRenderWindow(

   "Manual Ogre Window", // window title

   800,     // window width, in pixels

   600,     // window height, in pixels

   false,     // fullscreen or not

   0);      // use defaults for all other values

  // from here you can set up your camera and viewports as normal

  // get a pointer to the default base scene manager -- sufficient for our purposes

  SceneManager *sceneMgr = root->createSceneManager(ST_GENERIC);

  // create a single camera, and a viewport that takes up the whole window (default behavior)

  Camera *camera = sceneMgr->createCamera("MainCam");

  Viewport *vp = window->addViewport(camera);

  vp->setDimensions(0.0f, 0.0f, 1.0f, 1.0f);

  camera->setAspectRatio((float)vp->getActualWidth() / (float) vp->getActualHeight());

  camera->setFarClipDistance(1000.0f);

  camera->setNearClipDistance(5.0f);

  // Run the manual render loop. Since we are not using a frame listener in this case, we

  // will count to 15 seconds and then instead of exiting, we'll change the render window settings

  // and re-initialize it.

  bool renderLoop = true;

  Timer *timer = Ogre::PlatformManager::getSingleton().createTimer();

  timer->reset();

  float s = 0.0f;

  while (renderLoop && window->isActive()) {

   renderLoop = root->renderOneFrame();

   // accumulate total elapsed time

   s += (float)timer->getMilliseconds() / 1000.0f;

   // if greater than 15 seconds, break out of the loop

   if (s >= 15.0f)

    renderLoop = false;

   // we must call the windowing system's message pump each frame to

   // allow Ogre to process messages

   //PlatformManager::getSingleton().messagePump();

  }

 }

 catch (Exception &e) {

  std::cerr << e.getFullDescription() << std::endl;

 }

 delete root;

 return 0;

}

视口

通过视口上的一点与相机的原点产生世界空间中的一条光线

// x and y are in "normalized" (0.0 to 1.0) screen coordinates

Ray getCameraToViewportRay(Real x, Real y) const;

视口,创建多个视口，通过Z序（越高越在上）　确定覆盖效果，每个视口可以有不同的背景。

// assume window is a valid pointer to an existing render window, and

// a valid pointer to an existing camera instance

Viewport *vpTop, *vpBottom;

// second parameter is z-order, remaining params are position and size,

vpBottom = window->addViewport(camera, 0);

// create a smaller viewport on top, in the center, 25% of main vp size

vpTop = window->addViewport(camera, 1,

0.375f, 0.375f,

0.25, 0.25);

// set the background of the top window to blue (the default is black

// need to set the bottom window explicitly)

vpTop->setBackgroundColour(ColourValue(0.0f, 0.0f, 1.0f));

// an alternate way to set the color is to use the manifest constant

// vpTop->setBackgroundColour(ColourValue::Blue);

在多视口情况下，overlay缺省在每个视口中渲染。可以关掉。Skybox, Shadow也是如此。

vpTop->setOverlaysEnabled(false);

vpTop->setSkiesEnabled(false);

vpTop->setShadowsEnabled(true);