让你的OGRE demo也有loadingBar

OGRE demo loadingBar

做法：
(1)先在你的demo主类头文件里加入
   #include "ExampleLoadingBar.h"
(2)再在主类的protected域内加入data member:
   ExampleLoadingBar mLoadingBar;
(3)再在主类的protected域内加入member function:
           void loadResources(void)
        {

                mLoadingBar.start(mWindow, 1, 1, 0.75);

                // Turn off rendering of everything except overlays
                mSceneMgr->clearSpecialCaseRenderQueues();
                mSceneMgr->addSpecialCaseRenderQueue(RENDER_QUEUE_OVERLAY);
                mSceneMgr->setSpecialCaseRenderQueueMode(SceneManager::SCRQM_INCLUDE);
               
                // Initialise the rest of the resource groups, parse scripts etc
                ResourceGroupManager::getSingleton().initialiseAllResourceGroups();
                ResourceGroupManager::getSingleton().loadResourceGroup(
                        ResourceGroupManager::getSingleton().getWorldResourceGroupName(),
                        false, true);

                // Back to full rendering
                mSceneMgr->clearSpecialCaseRenderQueues();
                mSceneMgr->setSpecialCaseRenderQueueMode(SceneManager::SCRQM_EXCLUDE);

                mLoadingBar.finish();

        }
释疑：
在Demo的父类ExampleApplication中 loadResources如下实现：
        virtual void loadResources(void)
        {
                // Initialise, parse scripts etc
                ResourceGroupManager::getSingleton().initialiseAllResourceGroups();

        }
这个被override后，里面的操作被包含了，如红色的所示。咱不会少做事，所以放心用吧