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);
}
};