基于射线查询的方式，实现摄像机和地形的碰撞检测，防止摄像机穿透地面,这也是ogre demo中Terrian例子中的方法。
首先定义 RaySceneQuery* raySceneQuery = 0;
在CreateScene时候，创建场景查询
frameRenderingQueued事件中，进行射线查询，设定摄像机位置
raySceneQuery = mSceneMgr->createRayQuery(
Ray(mCamera->getPosition(), Vector3::NEGATIVE_UNIT_Y));//光线的位置和方向，垂直向下
然后在
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)//把摄像机定在地形个单位高的地方。
{
mCamera->setPosition(mCamera->getPosition().x,
i->worldFragment->singleIntersection.y + 10,
mCamera->getPosition().z);
}
return true;
}
这样就把摄像机设在离地形高10个单位的地方。
Ogre 中，每个节点有AABB(轴对齐包围盒),通过包围盒，可以实现碰撞检测判断。具体实现过程如下： 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）。 Code 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 } 下面是测试2个节点通过AABB判断碰撞的程序代码：
Code
#ifndef __gkd4_h_
#define __gkd4_h_
#include "ExampleApplication.h"
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
#include "../res/resource.h"
#endif
#include
#include
#include
#include
//两个场景节点
SceneNode*node1;
SceneNode* node2;
CEGUI::MouseButton convertOISMouseButtonToCegui(int buttonID)
{
switch (buttonID)
{ case 0: return CEGUI::LeftButton;
case 1: return CEGUI::RightButton;
case 2: return CEGUI::MiddleButton;
case 3: return CEGUI::X1Button;
default: return CEGUI::LeftButton;
}
}
class gkd4FrameListener : public ExampleFrameListener, public OIS::KeyListener, public OIS::MouseListener
{
private: SceneManager* mSceneMgr;
CEGUI::Renderer* mGUIRenderer;
bool mShutdownRequested;
bool mUseBufferedInputKeys, mUseBufferedInputMouse, mInputTypeSwitchingOn;
public: gkd4FrameListener(SceneManager *sceneMgr, RenderWindow* win, Camera* cam, CEGUI::Renderer* renderer) : ExampleFrameListener(win, cam, false, true), mGUIRenderer(renderer), mShutdownRequested(false), mUseBufferedInputKeys(false), mUseBufferedInputMouse(true),
mSceneMgr(sceneMgr)
{
mMouse->setEventCallback(this);
mKeyboard->setEventCallback(this); mInputTypeSwitchingOn = mUseBufferedInputKeys || mUseBufferedInputMouse;
}
bool frameStarted(const FrameEvent& evt)
{ bool ret = ExampleFrameListener::frameStarted(evt);
if(mUseBufferedInputMouse) { CEGUI::MouseCursor::getSingleton().show( ); }
else
{ CEGUI::MouseCursor::getSingleton().hide( ); } AxisAlignedBox spbox=node1->_getWorldAABB(); AxisAlignedBox cbbox=node2->_getWorldAABB();
if(spbox.intersects(cbbox))
{ node2->setScale(10,10,10); }
return ret;
}
bool processUnbufferedKeyInput(const FrameEvent& evt)
{
bool ret =ExampleFrameListener::processUnbufferedKeyInput(evt);
// see if switching is on, and you want to toggle if (mInputTypeSwitchingOn && mKeyboard->isKeyDown(OIS::KC_M) && mTimeUntilNextToggle <= 0)
{ switchMouseMode();
mTimeUntilNextToggle = 1;
}
if (mInputTypeSwitchingOn && mKeyboard->isKeyDown(OIS::KC_K) && mTimeUntilNextToggle <= 0)
{
// must be going from immediate keyboard to buffered keyboard switchKeyMode();
mTimeUntilNextToggle = 1;
}
return ret;
}
void requestShutdown(void)
{
mShutdownRequested = true;
}
void switchMouseMode()
{ mUseBufferedInputMouse = !mUseBufferedInputMouse; mMouse->setBuffered(mUseBufferedInputMouse);
}
//----------------------------------------------------------------- void switchKeyMode()
{ mUseBufferedInputKeys = !mUseBufferedInputKeys; mKeyboard->setBuffered(mUseBufferedInputKeys);
}
bool frameEnded(const FrameEvent& evt)
{
if (mShutdownRequested)
return false;
else
return ExampleFrameListener::frameEnded(evt);
}
//----------------------------------------------------------------//
bool mouseMoved( const OIS::MouseEvent &arg )
{
CEGUI::System::getSingleton().injectMouseMove( arg.state.X.rel, arg.state.Y.rel ); return true;
}
//----------------------------------------------------------------//
bool mousePressed( const OIS::MouseEvent &arg, OIS::MouseButtonID id )
{
CEGUI::System::getSingleton().injectMouseButtonDown(convertOISMouseButtonToCegui(id));
return true;
}
//----------------------------------------------------------------//
bool mouseReleased( const OIS::MouseEvent &arg, OIS::MouseButtonID id )
{
CEGUI::System::getSingleton().injectMouseButtonUp(convertOISMouseButtonToCegui(id));
return true;
}
//----------------------------------------------------------------//
bool keyPressed( const OIS::KeyEvent &arg )
{
if( arg.key == OIS::KC_ESCAPE )
mShutdownRequested = true;
CEGUI::System::getSingleton().injectKeyDown( arg.key ); CEGUI::System::getSingleton().injectChar( arg.text );
return true;
}
//----------------------------------------------------------------//
bool keyReleased( const OIS::KeyEvent &arg )
{
if( arg.key == OIS::KC_M )
mMouse->setBuffered( !mMouse->buffered() );
else if( arg.key == OIS::KC_K )
mKeyboard->setBuffered( !mKeyboard->buffered() ); CEGUI::System::getSingleton().injectKeyUp( arg.key ); return true;
}
};
class gkd4App : public ExampleApplication
{ private: CEGUI::OgreCEGUIRenderer* mGUIRenderer; CEGUI::System* mGUISystem;
public: gkd4App() : mGUIRenderer(0), mGUISystem(0) {} ~gkd4App()
{
if(mGUISystem)
{
delete mGUISystem;
mGUISystem = 0;
}
if(mGUIRenderer)
{
delete mGUIRenderer;
mGUIRenderer = 0;
}
}
protected: virtual void createCamera(void)
{
// Create the camera
mCamera = mSceneMgr->createCamera("PlayerCam");
// Position it at 500 in Z direction
mCamera->setPosition(Vector3(0,0,80));
// Look back along -Z
mCamera->lookAt(Vector3(0,0,-300));
mCamera->setNearClipDistance(5);
}
virtual bool configure(void)
{
// Show the configuration dialog and initialise the system
// You can skip this and use root.restoreConfig() to load configuration
// settings if you were sure there are valid ones saved in ogre.cfg
if(mRoot->showConfigDialog())
{
// If returned true, user clicked OK so initialise
// Here we choose to let the system create a default rendering window by passing 'true'
mWindow = mRoot->initialise(true);
// Let's add a nice window icon
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32 HWND hwnd;
mWindow->getCustomAttribute("WINDOW", (void*)&hwnd); LONG iconID = (LONG)LoadIcon( GetModuleHandle(0), MAKEINTRESOURCE(IDI_APPICON) );
SetClassLong( hwnd, GCL_HICON, iconID );
#endif return true;
}
else
{
return false;
}
}
// Just override the mandatory create scene method
virtual void createScene(void)
{
// setup GUI system
mGUIRenderer = new CEGUI::OgreCEGUIRenderer(mWindow, Ogre::RENDER_QUEUE_OVERLAY, false, 3000, mSceneMgr);
mGUISystem = new CEGUI::System(mGUIRenderer); CEGUI::Logger::getSingleton().setLoggingLevel(CEGUI::Informative);
// load scheme and set up defaults CEGUI::SchemeManager::getSingleton().loadScheme( (CEGUI::utf8*)"TaharezLookSkin.scheme");
mGUISystem->setDefaultMouseCursor( (CEGUI::utf8*)"TaharezLook", (CEGUI::utf8*)"MouseArrow");
mGUISystem->setDefaultFont((CEGUI::utf8*)"BlueHighway-12"); CEGUI::MouseCursor::getSingleton().setImage("TaharezLook", "MouseArrow"); CEGUI::MouseCursor::getSingleton().show( ); setupEventHandlers();
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);
// Set ambient light mSceneMgr->setAmbientLight(ColourValue(0.5, 0.5, 0.5));
// Create a light
Light* l = mSceneMgr->createLight("MainLight"); l->setPosition(20,80,50);
}
// Create new frame listener void createFrameListener(void) { mFrameListener= new gkd4FrameListener(mSceneMgr, mWindow, mCamera, mGUIRenderer);
mRoot->addFrameListener(mFrameListener);
}
void setupEventHandlers(void)
{ }
bool handleQuit(const CEGUI::EventArgs& e)
{
static_cast(mFrameListener)->requestShutdown();
return true;
}
};
#endif
// #ifndef __gkd4_h_
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。
Code
//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：
Code
#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);
}
};
在3中，我提到检测到碰撞时候，后移一个单位，摄像机会抖动，现在通过记录摄像机上步移动偏移量，如果检测到碰撞则反移回来，可以解决这个问题。
下面是修改后的代码：
Code
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
Vector3 oldPos = mCamera->getPosition();
SphereSceneQuery * pQuery=mSceneMgr->createSphereQuery(Sphere(mCamera->getPosition(),10),0x01);
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);
mCamera->moveRelative( - mTranslateVector);
}
}
}
return true;
}
本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/wangwang123654/archive/2009/12/10/4980450.aspx