Ogre采用树桩管理场景中的各种"元素"(摄像机、灯光、物体等)，所有的东西都挂在"树"上，不在"树"上的东西不会被渲染。 Ogre::SceneManager就是"树"的管理者，Ogre::SceneNode是从SceneManager中创建的（当然BSP和8*树的管理也和这两个类有关，这暂时不讨论）。 AABB(轴对齐包围盒) 这个东西是碰撞检测的基础，和它类似的还有OBB(有向包围盒)，由于OBB创建复杂，所以Ogre采用了AABB。最简单的碰撞检测： 通过Ogre::SceneNode::_getWorldAABB()可以取得这个叶子节点的AABB(Ogre::AxisAlignedBox)，Ogre::AxisAlignedBox封装了对AABB的支持，该类的成员函数Ogre::AxisAlignedBox::intersects()可以判断一个AABB和"球体、点、面以及其他面"的相交情况（碰撞情况）。 m_SphereNode树的叶子，挂了一个"球" m_CubeNode树的叶子，挂了一个"正方体" AxisAlignedBox spbox = m_SphereNode->_getWorldAABB(); AxisAlignedBox cbbox = m_CubeNode->_getWorldAABB(); if(spbox.intersects(cbbox)) { //相交
}
附上简单的AABB测试程序，碰撞之后模型放大十倍，当然碰撞之后的事情你可以随意修改#include"ExampleApplication.h" #include <stdio.h> class CollionFrameListener:public ExampleFrameListener { private: SceneNode* m_node; SceneNode*m_node2; SceneManager* mSceneMgr; public: CollionFrameListener(RenderWindow* win, Camera* cam,SceneNode* node,SceneNode*node22,SceneManager* manager) :ExampleFrameListener(win,cam),m_node(node),m_node2(node22),mSceneMgr(manager) { } bool frameStarted(const FrameEvent& evt) { AxisAlignedBox spbox=m_node->_getWorldAABB(); AxisAlignedBox cbbox=m_node2->_getWorldAABB(); if(spbox.intersects(cbbox)) { m_node2->setScale(10,10,10);
} return ExampleFrameListener::frameStarted(evt); } };
class CollionApplication:public ExampleApplication { protected: SceneNode*node1; SceneNode* node2; void createScene() { mSceneMgr->setAmbientLight(ColourValue(1,1,1));
Entity* ent1=mSceneMgr->createEntity("robot","robot.mesh"); node1=mSceneMgr->getRootSceneNode()->createChildSceneNode("robotnode"); node1->attachObject(ent1); Entity *ent2=mSceneMgr->createEntity("ogrehead","ogreHead.mesh"); node2=mSceneMgr->getRootSceneNode()->createChildSceneNode("ogreheadnode",Vector3(2,0,0)); node2->attachObject(ent2);
} void createFrameListener() { mFrameListener=new CollionFrameListener(mWindow,mCamera,node1,node2,mSceneMgr); mFrameListener->showDebugOverlay(true); mRoot->addFrameListener(mFrameListener); } };
INT WINAPI WinMain( HINSTANCE hInstance, HINSTANCE, LPSTR, int ) { CollionApplication app; app.go(); }区域查询：简单的讲就是，查询某一区域中有什么东西，分为AABB、球体、面查询。 //创建一个球体查询，这里的100是m_SphereNode挂着的那个球体的半径 SphereSceneQuery * pQuery=m_SceneMgr-＞createSphereQuery(Sphere(m_SphereNode-＞getPosition(),100)); //执行这个查询 SceneQueryResult QResult=pQuery-＞execute(); //遍历查询列表找出范围内的物体 for (SceneQueryResultMovableList::iterator iter = QResult.movables.begin(); iter != QResult.movables.end();++iter) { MovableObject* pObject=static_cast＜MovableObject*＞(*iter); if(pObject) { if(pObject-＞getMovableType()=="Entity") { Entity* ent = static_cast＜Entity*＞(pObject); //这里简化了操作，由于只有一个"球体"和一个"正方体"， //所以只判断了球体和正方体的相交 if(ent-＞getName()=="cube") { //改变位置防止物体重叠 vtl=-vtl; m_SphereNode-＞translate(vtl); break; } } } }
新建一个空的ogre程序，将这个代码添加到你的cpp文件中就可以运行，这个例子是如果碰撞就将模型放大十倍，当然碰撞之后的代码你可以随便修改#include"ExampleApplication.h" #include <stdio.h> class CollionFrameListener:public ExampleFrameListener { private: SceneNode* m_node; SceneManager* mSceneMgr; public: CollionFrameListener(RenderWindow* win, Camera* cam,SceneNode* node,SceneManager* manager) :ExampleFrameListener(win,cam),m_node(node),mSceneMgr(manager) { } bool frameStarted(const FrameEvent& evt) { SphereSceneQuery * pQuery=mSceneMgr->createSphereQuery(Sphere(m_node->getPosition(),10)); SceneQueryResult QResult=pQuery->execute(); for (SceneQueryResultMovableList::iterator iter = QResult.movables.begin(); iter != QResult.movables.end();++iter) { MovableObject* pObject=static_cast<MovableObject*>(*iter); if(pObject) { if(pObject->getMovableType()=="Entity") { Entity* ent = static_cast<Entity*>(pObject); if(ent->getName()=="ogrehead") { m_node->setScale(10,10,10); break; } } } }
return ExampleFrameListener::frameStarted(evt); } };
class CollionApplication:public ExampleApplication { protected: SceneNode*node1; void createScene() { mSceneMgr->setAmbientLight(ColourValue(1,1,1));
Entity* ent1=mSceneMgr->createEntity("robot","robot.mesh"); node1=mSceneMgr->getRootSceneNode()->createChildSceneNode("robotnode"); node1->attachObject(ent1); Entity *ent2=mSceneMgr->createEntity("ogrehead","ogreHead.mesh"); SceneNode* node2=mSceneMgr->getRootSceneNode()->createChildSceneNode("ogreheadnode",Vector3(2,0,0)); node2->attachObject(ent2); } void createFrameListener() { mFrameListener=new CollionFrameListener(mWindow,mCamera,node1,mSceneMgr); mFrameListener->showDebugOverlay(true); mRoot->addFrameListener(mFrameListener); } };
INT WINAPI WinMain( HINSTANCE hInstance, HINSTANCE, LPSTR, int ) { CollionApplication app; app.go(); }相交查询:遍历所有的对象，找到一对一对的相交物体（废话呀，相交当然至少两个物体）。 //创建相交检测 IntersectionSceneQuery* pISQuery=m_SceneMgr-＞createIntersectionQuery(); //执行查询 IntersectionSceneQueryResult QResult=pISQuery-＞execute(); //遍历查询列表找出两个相交的物体 for (SceneQueryMovableIntersectionList::iterator iter = QResult.movables2movables.begin(); iter != QResult.movables2movables.end();++iter) { SceneQueryMovableObjectPair pObject=static_cast＜SceneQueryMovableObjectPair＞(*iter); //if(pObject) { String strFirst=pObject.first-＞getName(); String strSecond=pObject.second-＞getName(); //下面加入你自己的两个物体相交判断代码，或者简单的用AABB的判断方法， } }
在Ogre中，可以创建一个查询器，比如球体查询器，AABB查询器，面查询器等。下面我们以最常用的球形查询器为例来说明：
如下面的代码，我们首先创建一个球形查询器，它需要定义一个球体，我们把它的位置，设置为摄像机的位置，半径为10，掩码为第二个参数，默认为-1，
通过掩码，可以把碰撞的物体分成不同的组，比如我们设置球形场景查询器的掩码为0x1,则它只检测和它掩码相同物体的碰撞。该摄像机检测到entity对象后，就把摄像机位置沿摄像机方向，向后移动一个单位，这样会实现碰撞检测，但是摄像机因为向后有个移动，所以会有抖动。
//创建球形查询器,第二个参数表示掩码,默认情况下为-1 SphereSceneQuery * pQuery=mSceneMgr->createSphereQuery(Sphere(mCamera->getPosition(),10)); SceneQueryResult QResult=pQuery->execute(); for (std::list<MovableObject*>::iterator iter = QResult.movables.begin(); iter != QResult.movables.end();++iter) { MovableObject* pObject=static_cast<MovableObject*>(*iter); if(pObject) { if(pObject->getMovableType()=="Entity") { Entity* ent = static_cast<Entity*>(pObject); //if(ent->getName()=="Head") //{ // //m_node->setScale(10,10,10); // pObject->getParentNode()->scale(0.5,0.5,0.5); // break; //} Ogre::Vector3 v = mCamera->getPosition(); Ogre::Vector3 d = mCamera->getDirection(); v = v + d*(-1); mCamera->setPosition(v); } } }全部的代码: #include "ExampleApplication.h" RaySceneQuery* raySceneQuery = 0; // Event handler to add ability to alter curvature class TerrainFrameListener : public ExampleFrameListener { public: SceneManager* mSceneMgr; TerrainFrameListener(SceneManager *sceneMgr,RenderWindow* win, Camera* cam) : ExampleFrameListener(win, cam) { // Reduce move speed mMoveSpeed = 50; mSceneMgr = sceneMgr; } bool frameRenderingQueued(const FrameEvent& evt) { if( ExampleFrameListener::frameRenderingQueued(evt) == false ) return false; // clamp to terrain static Ray updateRay; updateRay.setOrigin(mCamera->getPosition()); updateRay.setDirection(Vector3::NEGATIVE_UNIT_Y); raySceneQuery->setRay(updateRay); RaySceneQueryResult& qryResult = raySceneQuery->execute(); RaySceneQueryResult::iterator i = qryResult.begin(); if (i != qryResult.end() && i->worldFragment)//把摄像机定在地形10个单位高的地方。 { mCamera->setPosition(mCamera->getPosition().x, i->worldFragment->singleIntersection.y + 10, mCamera->getPosition().z); } //创建球形查询器,第二个参数表示掩码,默认情况下为-1 SphereSceneQuery * pQuery=mSceneMgr->createSphereQuery(Sphere(mCamera->getPosition(),10)); SceneQueryResult QResult=pQuery->execute(); for (std::list<MovableObject*>::iterator iter = QResult.movables.begin(); iter != QResult.movables.end();++iter) { MovableObject* pObject=static_cast<MovableObject*>(*iter); if(pObject) { if(pObject->getMovableType()=="Entity") { Entity* ent = static_cast<Entity*>(pObject); //if(ent->getName()=="Head") //{ // //m_node->setScale(10,10,10); // pObject->getParentNode()->scale(0.5,0.5,0.5); // break; //} Ogre::Vector3 v = mCamera->getPosition(); Ogre::Vector3 d = mCamera->getDirection(); v = v + d*(-1); mCamera->setPosition(v); } } } return true; } }; class TerrainApplication : public ExampleApplication { public: TerrainApplication() {} ~TerrainApplication() { delete raySceneQuery; } protected: virtual void chooseSceneManager(void) { // Get the SceneManager, in this case a generic one mSceneMgr = mRoot->createSceneManager("TerrainSceneManager"); } virtual void createCamera(void) { // Create the camera mCamera = mSceneMgr->createCamera("PlayerCam"); // Position it at 500 in Z direction mCamera->setPosition(Vector3(128,25,128)); // Look back along -Z mCamera->lookAt(Vector3(0,0,-300)); mCamera->setNearClipDistance( 1 ); mCamera->setFarClipDistance( 1000 ); } // Just override the mandatory create scene method void createScene(void) { // Set ambient light mSceneMgr->setAmbientLight(ColourValue(0.5, 0.5, 0.5)); // Create a light Light* l = mSceneMgr->createLight("MainLight"); // Accept default settings: point light, white diffuse, just set position // NB I could attach the light to a SceneNode if I wanted it to move automatically with // other objects, but I don't l->setPosition(20,80,50); // Fog // NB it's VERY important to set this before calling setWorldGeometry // because the vertex program picked will be different ColourValue fadeColour(0.93, 0.86, 0.76); mSceneMgr->setFog( FOG_LINEAR, fadeColour, .001, 500, 1000); mWindow->getViewport(0)->setBackgroundColour(fadeColour); std::string terrain_cfg("terrain.cfg"); mSceneMgr -> setWorldGeometry( terrain_cfg ); // Infinite far plane? if (mRoot->getRenderSystem()->getCapabilities()->hasCapability(RSC_INFINITE_FAR_PLANE)) { mCamera->setFarClipDistance(0); } // Set a nice viewpoint mCamera->setPosition(707,2500,528); mCamera->setOrientation(Quaternion(-0.3486, 0.0122, 0.9365, 0.0329)); //mRoot -> showDebugOverlay( true ); raySceneQuery = mSceneMgr->createRayQuery( Ray(mCamera->getPosition(), Vector3::NEGATIVE_UNIT_Y));//光线的位置和方向，垂直向下 Entity* ogreHead = mSceneMgr->createEntity("Head", "ogrehead.mesh"); //创建ogre head实体，测试通过射线查询movable来实现摄像机碰撞检测 SceneNode* headNode = mSceneMgr->getRootSceneNode()->createChildSceneNode("ogreHead"); headNode->attachObject(ogreHead); headNode->setPosition(500.0, 100.0, 500.0); headNode->scale(Vector3(2,2,2)); } // Create new frame listener void createFrameListener(void) { mFrameListener= new TerrainFrameListener(mSceneMgr,mWindow, mCamera); mRoot->addFrameListener(mFrameListener); } };