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);
}
};
