最简单的Ogre系列之一——Ogre框架程序（不使用ExampleListener/Application）

本文参考Ogre官网上的MinimalApplication写了一个最简单的Ogre程序，不包含任何资源文件，当然了，也没有任何功能: )。本文写作的初衷是：

（1）ExampleListener/Application包含的内容过于丰富，不便于在此基础上写出简单的程序应用，如2D程序。它需要的资源文件和相应的配置文件对于简单的程序显得臃肿。

（2）现有的MinimalApplication混淆了Listener和Application，而且将所有文件写到了一个程序里面，文档结构不清晰。

（3）更重要的是通过自己写这样一个程序，能够了解Ogre建立的详细过程，有助于理解Ogre的框架。

闲言少叙，进入正题。建立一个Win32程序，程序包括三个文件，分别是SimpleListener.h，SimpleApplication.h和main.cpp。该程序使用的是Ogre 1.6.5版本，1.7.x版本可能需要修改相应的include文件。

程序需要包含库OgreMain_d.lib、OIS_d.lib（Debug模式），或OgreMain.lib、OIS.lib（Release模式）；需要包含dll文件OgreMain_d.dll、OIS_d.dll、RenderSystem_Direct3D9_d.dll（Debug模式），或OgreMain.dll、OIS.dll、RenderSystem_Direct3D9.dll（Release模式）。

程序需要建立一个空文件resources.cfg。

程序需要建立一个文件Plugins.cfg，其内容为

# Defines plugins to load
# Define plugin folder
PluginFolder=.
# Define plugins
Plugin=RenderSystem_Direct3D9_d

下面是SimpleListener.h的内容。

/*
======================================================================
SimpleListener.h --- protoype to show off the simple ogre listener.
----------------------------------------------------------------------
Author : Zhu Xiaoyang (xiaoyang.zhu@ia.ac.cn)
Creation Date : Apr 14 2011
Description:
This is a mini Ogre Listener, including SimpleFrameListener,
SimpleKeyListener and SimpleMouseListener.
=======================================================================
*/
#ifndef __SimpleListener_H__
#define __SimpleListener_H__
#include "Ogre.h"
#include "OgreFrameListener.h"
#include <OIS/OIS.h>
using namespace Ogre;
/**
----------------------------------------------------------------------
class SimpleFrameListener
----------------------------------------------------------------------
*/
class SimpleFrameListener : public FrameListener
{
public:
SimpleFrameListener(OIS::Keyboard* keyboard, OIS::Mouse* mouse)
{
mKeyboard = keyboard;
mMouse    = mouse;
}
//This gets called before the next frame is being rendered.
bool frameStarted(const FrameEvent& evt)
{
//update the input devices
mKeyboard->capture();
mMouse->capture();
//exit if key KC_ESCAPE pressed
if( mKeyboard->isKeyDown( OIS::KC_ESCAPE ) )
return false;
else
return true;
}
//This gets called at the end of a frame
bool frameEnded(const FrameEvent& evt)
{
return true;
}
private:
OIS::Keyboard* mKeyboard;
OIS::Mouse*    mMouse;
};
/**
----------------------------------------------------------------------
class SimpleKeyListener
----------------------------------------------------------------------
*/
class SimpleKeyListener : public OIS::KeyListener
{
public:
bool keyPressed    (const OIS::KeyEvent& e)   { return true; }
bool keyReleased   (const OIS::KeyEvent& e)   { return true; }
};
/**
----------------------------------------------------------------------
class SimpleMouseListener
----------------------------------------------------------------------
*/
class SimpleMouseListener : public OIS::MouseListener
{
public:
bool mouseMoved    (const OIS::MouseEvent& e) { return true; }
bool mousePressed  (const OIS::MouseEvent& e, OIS::MouseButtonID id) { return true; }
bool mouseReleased (const OIS::MouseEvent& e, OIS::MouseButtonID id) { return true; }
};
#endif //__SimpleListener_H__

下面是SimpleApplication.h的内容。

/*
==========================================================================
SimpleApplication.h --- protoype to show off the simple ogre application.
--------------------------------------------------------------------------
Author : Zhu Xiaoyang (xiaoyang.zhu@ia.ac.cn)
Creation Date : Apr 14 2011
Description:
This is a mini Ogre Application.  It does noting.
==========================================================================
*/
#ifndef __SimpleApplication_H__
#define __SimpleApplication_H__
#include "Ogre.h"
#include "SimpleListener.h"
using namespace Ogre;
/**
----------------------------------------------------------------------
class SimpleApplication
----------------------------------------------------------------------
*/
class SimpleApplication
{
public:
SimpleApplication()
{
mRoot = 0;
}
~SimpleApplication()
{
if(mRoot)
OGRE_DELETE mRoot;
}
//start example
void go()
{
if( !setup() )
return;
/**
----------------------------------------------------------------------
8 start rendering
@ blocks until a frame listener returns false.
eg. from pressing escape in this example.
----------------------------------------------------------------------
*/
mRoot->startRendering();
/**
----------------------------------------------------------------------
9 clean up
----------------------------------------------------------------------
*/
destroyScene();
}
//setup Ogre
bool setup()
{
/**
----------------------------------------------------------------------
1 Enter ogre
----------------------------------------------------------------------
*/
mRoot = new Root;
/**
----------------------------------------------------------------------
2 Configure resource paths
@ Load resource paths from config file
File format is:
[ResourceGroupName]
ArchiveType=Path
.. repeat
For example:
[General]
FileSystem=media/
zip=packages/level1.zip
----------------------------------------------------------------------
*/
ConfigFile cf;
cf.load("resources.cfg");
//Go through all sections & settings in the file
ConfigFile::SectionIterator seci = cf.getSectionIterator();
String secName, typeName, archName;
while ( seci.hasMoreElements() )
{
secName = seci.peekNextKey();
ConfigFile::SettingsMultiMap  *settings = seci.getNext();
ConfigFile::SettingsMultiMap::iterator i;
for (i = settings->begin(); i != settings->end(); ++i)
{
typeName = i->first;
archName = i->second;
ResourceGroupManager::getSingleton().addResourceLocation(
archName, typeName, secName);
}
}
/**
----------------------------------------------------------------------
3 Configures the application and creates the window
----------------------------------------------------------------------
*/
if ( !mRoot->showConfigDialog() )
{
//Ogre
delete mRoot;
return false; //Exit the application on cancel
}
mWindow = mRoot->initialise(true, "Simple Ogre App");
ResourceGroupManager::getSingleton().initialiseAllResourceGroups();
/**
----------------------------------------------------------------------
4 Create the SceneManager
@ SceneManager Type
ST_GENERIC = octree
ST_EXTERIOR_CLOSE = simple terrain
ST_EXTERIOR_FAR = nature terrain (depreciated)
ST_EXTERIOR_REAL_FAR = paging landscape
ST_INTERIOR = Quake3 BSP
----------------------------------------------------------------------
*/
mSceneMgr = mRoot->createSceneManager(ST_GENERIC);
/**
----------------------------------------------------------------------
5 Create the camera
----------------------------------------------------------------------
*/
mCamera = mSceneMgr->createCamera("SimpleCamera");
/**
----------------------------------------------------------------------
6 Create one viewport, entire window
----------------------------------------------------------------------
*/
Viewport* viewport = mWindow->addViewport(mCamera);
/**
----------------------------------------------------------------------
7 Add OIS input handling
----------------------------------------------------------------------
*/
OIS::ParamList pl;
size_t windowHnd = 0;
std::ostringstream windowHndStr;
//tell OIS about the Ogre window
mWindow->getCustomAttribute("WINDOW", &windowHnd);
windowHndStr<<windowHnd;
pl.insert( std::make_pair( std::string("WINDOW"), windowHndStr.str() ) );
//setup the manager, keyboard and mouse to handle input
inputManager = OIS::InputManager::createInputSystem( pl );
keyboard = static_cast<OIS::Keyboard*>(inputManager->createInputObject( OIS::OISKeyboard, true ) );
mouse    = static_cast<OIS::Mouse*>(inputManager->createInputObject( OIS::OISMouse,    true ) );
//tell OIS about the window's dimensions
unsigned int width, height, depth;
int top, left;
mWindow->getMetrics(width, height, depth, left, top);
const OIS::MouseState &ms = mouse->getMouseState();
ms.width  = width;
ms.height = height;
//everything is set up, now we listen for input and frames (replaces while loops)
//key events
keyListener = new SimpleKeyListener();
keyboard->setEventCallback(keyListener);
//mouse events
mouseListener = new SimpleMouseListener();
mouse->setEventCallback(mouseListener);
//render events
mFrameListener = new SimpleFrameListener(keyboard, mouse);
mRoot->addFrameListener(mFrameListener);
return true;
}
//clean Ogre
void destroyScene()
{
//OIS
inputManager->destroyInputObject(mouse);             mouse = 0;
inputManager->destroyInputObject(keyboard);          keyboard = 0;
OIS::InputManager::destroyInputSystem(inputManager); inputManager = 0;
//listeners
delete mFrameListener;
delete mouseListener;
delete keyListener;
}
private:
Root* mRoot;
Camera* mCamera;
SceneManager* mSceneMgr;
RenderWindow* mWindow;
//OIS
OIS::InputManager* inputManager;
OIS::Keyboard* keyboard;
OIS::Mouse* mouse;
//Listener
SimpleKeyListener* keyListener;
SimpleMouseListener* mouseListener;
SimpleFrameListener* mFrameListener;
};
#endif //__SimpleApplication_H__

下面是main.cpp的内容。

#include "SimpleApplication.h"
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
#define WIN32_LEAN_AND_MEAN
#include "windows.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR strCmdLine, INT )
#else
int main(int argc, char **argv)
#endif
{
// Create application object
SimpleApplication app;
srand(time(0));
try {
app.go();
} catch( Exception& e ) {
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
MessageBoxA( NULL, e.getFullDescription().c_str(), "An exception has occured!", MB_OK | MB_ICONERROR | MB_TASKMODAL);
#else
std::cerr << "An exception has occured: " << e.getFullDescription();
#endif
}
return 0;
}
#ifdef __cplusplus
}
#endif