自学教程：C++ GetSpeed函数代码示例

void AirsideFollowMeCarInSim::ServicingFlight(){	double dDist = m_pServiceFlight->GetDistInResource() + m_pServiceFlight->GetLogEntry().GetAirsideDescStruct().dLength;	CPoint2008 CarPos = m_pServiceFlight->GetResource()->GetDistancePoint(dDist);	SetMode(OnService);	SetSpeed(m_pServiceFlight->GetSpeed());	ElapsedTime tTime = ElapsedTime(2.0*CarPos.distance(GetPosition())/GetSpeed()) + GetTime();	SetTime(tTime);	if(GetResource() != m_pServiceFlight->GetResource())		GetResource()->SetExitTime(this,tTime);	SetResource(m_pServiceFlight->GetResource());	SetPosition(CarPos);	SetDistInResource(dDist);	WirteLog(CarPos,GetSpeed(),tTime);	m_pServiceFlight->SetBeginFollowMeCarService();	AirsideFollowMeCarServiceEvent* pEvent = new AirsideFollowMeCarServiceEvent(m_pServiceFlight);	pEvent->setTime(tTime);	pEvent->addEvent();}

void Asserv::stop(bool emergency){    float actualSpeed = GetSpeed();    /* distance theorique (temps continu) pour annuler la vitesse avec un freinage maximum et constant*/    if (emergency){        d_freinage  = (actualSpeed*actualSpeed) * .5 / decEmergency;    } else {        d_freinage  = (actualSpeed*actualSpeed) * .5 / dec;        }    setTarget(initialSens * d_freinage, 0.0);    emergencyStop = emergency;}

void CVideoReferenceClock::SetSpeed(double Speed){  CSingleLock SingleLock(m_CritSection);  //dvdplayer can change the speed to fit the rereshrate  if (m_UseVblank)  {    if (Speed != m_ClockSpeed)    {      m_ClockSpeed = Speed;      CLog::Log(LOGDEBUG, "CVideoReferenceClock: Clock speed %f%%", GetSpeed() * 100.0);    }  }}

void PathBehavior::SerializeTo(gd::SerializerElement & element) const{    SerializePathsTo(element.AddChild("paths"));    element.SetAttribute("currentPath", GetCurrentPathName());    element.SetAttribute("speed", GetSpeed());    element.SetAttribute("offsetX", GetOffsetX());    element.SetAttribute("offsetY", GetOffsetY());    element.SetAttribute("angleOffset", angleOffset);    element.SetAttribute("reverseAtEnd", ReverseAtEnd());    element.SetAttribute("stopAtEnd", StopAtEnd());    element.SetAttribute("followAngle", FollowAngle());}

void PhysicalObj::Collide(collision_t collision, PhysicalObj* collided_obj, const Point2d& position){  Point2d contactPos;  Double contactAngle;  switch (collision) {  case NO_COLLISION:    // Nothing more to do!    return;  case COLLISION_ON_GROUND:    ContactPointAngleOnGround(position, contactPos, contactAngle);    ASSERT(!collided_obj);    break;  case COLLISION_ON_OBJECT:    contactPos = position;    contactAngle = - GetSpeedAngle();    // Compute the new speed norm of this and collided_obj, new speed angle will be set    // thanks to Rebound()    // Get the current speed    Double v1, v2, mass1, angle1, angle2, mass2;    collided_obj->GetSpeed(v1, angle1);    GetSpeed(v2, angle2);    mass1 = GetMass();    mass2 = collided_obj->GetMass();    // Give speed to the other object    // thanks to physic and calculations about chocs, we know that :    //    // v'1 =  ((m1 - m2) * v1 + 2m1 *v2) / (m1 + m2)    // v'2 =  ((m2 - m1) * v2 + 2m1 *v1) / (m1 + m2)    collided_obj->SetSpeed(abs(((mass1 - mass2) * v1 + 2 * mass1 *v2 * m_cfg.m_rebound_factor) / (mass1 + mass2)),                           angle1);    SetSpeed(abs(((mass2 - mass1) * v2 + 2 * mass1 *v1 * m_cfg.m_rebound_factor) / (mass1 + mass2)), angle2);    break;  }  // Mark it as last collided object  m_last_collided_object = collided_obj;  // Make it rebound!!  MSG_DEBUG("physic.state", "%s rebounds at %.3f,%.3f", GetName().c_str(),            contactPos.x.tofloat(), contactPos.y.tofloat());  Rebound(contactPos, contactAngle);  CheckRebound();}

void CBubbling::Spawn( void ){	Precache();	SetModel( GetModelName() );		// Set size	SetSolidType( SOLID_NOT );							// Remove model & collisions	SetRenderAmount( 0 );								// The engine won't draw this model if this is set to 0 and blending is on	SetRenderMode( kRenderTransTexture );	int speed = fabs( GetSpeed() );	// HACKHACK!!! - Speed in rendercolor	SetRenderColor( Vector( speed >> 8, speed & 255, ( GetSpeed() < 0 ) ? 1 : 0 ) );	if( !GetSpawnFlags().Any( SF_BUBBLES_STARTOFF ) )	{		SetThink( &CBubbling::FizzThink );		SetNextThink( gpGlobals->time + 2.0 );		m_state = true;	}	else		m_state = false;}

void CTriggerPush::Touch( CBaseEntity *pOther ){	// UNDONE: Is there a better way than health to detect things that have physics? (clients/monsters)	switch( pOther->GetMoveType() )	{	case MOVETYPE_NONE:	case MOVETYPE_PUSH:	case MOVETYPE_NOCLIP:	case MOVETYPE_FOLLOW:		return;	default: break;	}	if( pOther->GetSolidType() != SOLID_NOT && pOther->GetSolidType() != SOLID_BSP )	{		// Instant trigger, just transfer velocity and remove		if( GetSpawnFlags().Any( SF_TRIG_PUSH_ONCE ) )		{			pOther->SetAbsVelocity( pOther->GetAbsVelocity() + ( GetSpeed() * GetMoveDir() ) );			if( pOther->GetAbsVelocity().z > 0 )				pOther->GetFlags().ClearFlags( FL_ONGROUND );			UTIL_Remove( this );		}		else		{	// Push field, transfer to base velocity			Vector vecPush = ( GetSpeed() * GetMoveDir() );			if( pOther->GetFlags().Any( FL_BASEVELOCITY ) )				vecPush = vecPush + pOther->GetBaseVelocity();			pOther->SetBaseVelocity( vecPush );			pOther->GetFlags() |= FL_BASEVELOCITY;			//			ALERT( at_console, "Vel %f, base %f/n", pevToucher->velocity.z, pevToucher->basevelocity.z );		}	}}

// 添加到CByteArraybool CShape::CodeToDataBlock(DBWriteSet& setWriteDB, bool bExData){	CBaseObject::CodeToDataBlock(setWriteDB,bExData);	setWriteDB.AddToByteArray((BYTE)GetCurRgnType());	setWriteDB.AddToByteArray(GetRegionID());	setWriteDB.AddToByteArray(GetRegionExID());	setWriteDB.AddToByteArray(GetPosX());	setWriteDB.AddToByteArray(GetPosY());	setWriteDB.AddToByteArray(GetDir());	setWriteDB.AddToByteArray(GetPos());	setWriteDB.AddToByteArray(GetSpeed());	setWriteDB.AddToByteArray(GetState());	setWriteDB.AddToByteArray(GetAction());	return true;}

void CRock_Fall::Update(float fElapsedTime){	AnimationManager::GetInstance()->Update(fElapsedTime, *GetAnimInfo());	//CEntity::Update(fElapsedTime);	SetPosX(GetPosX());	SetPosY(GetPosY() + GetSpeed() * fElapsedTime);	CCamera* Game_Camera = CCamera::GetInstance();	if(this->GetPosY() > Game_Camera->GetPosY() + Game_Camera->GetHeight())	{		CRemoveEntityMessage* pMsg = new CRemoveEntityMessage(this);		CSGD_MessageSystem::GetInstance()->SendMsg(pMsg);		pMsg = nullptr;	}}

// 添加到CByteArraybool CShape::AddShapeToByteArray(vector<BYTE>* pByteArray){	_AddToByteArray(pByteArray,(CGUID&)GetExID());	_AddToByteArray(pByteArray, (long)GetCurRgnType());	_AddToByteArray(pByteArray, GetRegionID());	_AddToByteArray(pByteArray, GetRegionExID());	_AddToByteArray(pByteArray, GetPosX());	_AddToByteArray(pByteArray, GetPosY());	_AddToByteArray(pByteArray, GetDir());	_AddToByteArray(pByteArray, GetPos());	_AddToByteArray(pByteArray, GetSpeed());	_AddToByteArray(pByteArray, GetState());	_AddToByteArray(pByteArray, GetAction());	return true;}

//发送变化的速度值到客户端void CMoveShape::SendChangedSpeedToClients(){	//if(m_bSpeedLvlChanged)	{		m_bSpeedLvlChanged = false;		CMessage msg(MSG_S2C_SHAPE_CHANGEMOVEMODE);		msg.Add(GetType());		msg.Add(GetExID());		//移动模式		msg.Add(static_cast<char>(GetIsRun()==false?0:1));		//当前速度		msg.Add( GetSpeed());		//变化比率		msg.Add(GetSpeedChangedRatio());		msg.SendToAround(this);	}}

void CBaseDoor::Spawn(){	Precache();	SetMovedir( this );	if( GetSkin() == 0 )	{//normal door		if( GetSpawnFlags().Any( SF_DOOR_PASSABLE ) )			SetSolidType( SOLID_NOT );		else			SetSolidType( SOLID_BSP );	}	else	{// special contents		SetSolidType( SOLID_NOT );		GetSpawnFlags().AddFlags( SF_DOOR_SILENT );	// water is silent for now	}	SetMoveType( MOVETYPE_PUSH );	SetAbsOrigin( GetAbsOrigin() );	SetModel( GetModelName() );	if( GetSpeed() == 0 )		SetSpeed( 100 );	m_vecPosition1 = GetAbsOrigin();	// Subtract 2 from size because the engine expands bboxes by 1 in all directions making the size too big	m_vecPosition2 = m_vecPosition1 + ( GetMoveDir() * ( fabs( GetMoveDir().x * ( GetBounds().x - 2 ) ) + fabs( GetMoveDir().y * ( GetBounds().y - 2 ) ) + fabs( GetMoveDir().z * ( GetBounds().z - 2 ) ) - m_flLip ) );	ASSERTSZ( m_vecPosition1 != m_vecPosition2, "door start/end positions are equal" );	if( GetSpawnFlags().Any( SF_DOOR_START_OPEN ) )	{	// swap pos1 and pos2, put door at pos2		SetAbsOrigin( m_vecPosition2 );		m_vecPosition2 = m_vecPosition1;		m_vecPosition1 = GetAbsOrigin();	}	m_toggle_state = TS_AT_BOTTOM;	// if the door is flagged for USE button activation only, use NULL touch function	if( GetSpawnFlags().Any( SF_DOOR_USE_ONLY ) )	{		SetTouch( NULL );	}	else // touchable button		SetTouch( &CBaseDoor::DoorTouch );}

void cArrowEntity::OnHitEntity(cEntity & a_EntityHit, const Vector3d & a_HitPos){	if (!a_EntityHit.IsMob() && !a_EntityHit.IsMinecart() && !a_EntityHit.IsPlayer())	{		// Not an entity that interacts with an arrow		return;	}		int Damage = (int)(GetSpeed().Length() / 20 * m_DamageCoeff + 0.5);	if (m_IsCritical)	{		Damage += m_World->GetTickRandomNumber(Damage / 2 + 2);	}	a_EntityHit.TakeDamage(dtRangedAttack, this, Damage, 1);		Destroy();}

void clRailPositioner::Update( float dt ){	float S = GetSpeed( dt );	// move to properties	float PitchRate = 90.0f * dt;	float PanRate = 90.0f * dt;	PitchRate *= Env->Console->IsKeyPressed( LK_SHIFT ) ? 3.0f : 1.0f;	PanRate *= Env->Console->IsKeyPressed( LK_SHIFT ) ? 3.0f : 1.0f;	if ( Env->Console->IsKeyPressed( LK_LEFT  ) ) { FPitch -= PitchRate; }	if ( Env->Console->IsKeyPressed( LK_RIGHT ) ) { FPitch += PitchRate; }	if ( Env->Console->IsKeyPressed( LK_E ) )     { FPan -= PanRate; }	if ( Env->Console->IsKeyPressed( LK_C ) )     { FPan += PanRate; }	FPitch = Math::ClipAngleTo0_360( FPitch );	FPan   = Math::ClipAngleTo0_360( FPan );	LMatrix4 PitchMtx;	PitchMtx.IdentityMatrix();	PitchMtx.RotateMatrixAxis( Linderdaum::Math::DegToRad( -FPitch ), FUpVector );	LVector3 ViewDir = -( PitchMtx * FDirVector );	LVector3 SideDir = -( FUpVector.Cross( ViewDir ) );	if ( Env->Console->IsKeyPressed( LK_Q ) || Env->Console->IsKeyPressed( LK_1 ) ) { FPosition += S * FUpVector; }	if ( Env->Console->IsKeyPressed( LK_Z ) || Env->Console->IsKeyPressed( LK_2 ) ) { FPosition -= S * FUpVector; }	if ( Env->Console->IsKeyPressed( LK_W ) || Env->Console->IsKeyPressed( LK_UP   ) ) { FPosition += -ViewDir * S; }	if ( Env->Console->IsKeyPressed( LK_S ) || Env->Console->IsKeyPressed( LK_DOWN ) ) { FPosition += ViewDir * S; }	if ( Env->Console->IsKeyPressed( LK_A ) ) { FPosition +=  SideDir * S; }	if ( Env->Console->IsKeyPressed( LK_D ) ) { FPosition += -SideDir * S; }	LMatrix4 Rotation = LMatrix4::GetRotateMatrixAxis( Math::DegToRad( FPan ), SideDir ) * LMatrix4::GetRotateMatrixAxis( Math::DegToRad( FPitch ), FUpVector );	FCurrentTransform = LMatrix4::GetTranslateMatrix( -FPosition ) * Rotation;}

void cArrowEntity::OnHitEntity(cEntity & a_EntityHit, const Vector3d & a_HitPos){	super::OnHitEntity(a_EntityHit, a_HitPos);	int Damage = static_cast<int>(GetSpeed().Length() / 20 * m_DamageCoeff + 0.5);	if (m_IsCritical)	{		Damage += m_World->GetTickRandomNumber(Damage / 2 + 2);	}	unsigned int PowerLevel = m_CreatorData.m_Enchantments.GetLevel(cEnchantments::enchPower);	if (PowerLevel > 0)	{		int ExtraDamage = static_cast<int>(ceil(0.25 * (PowerLevel + 1)));		Damage += ExtraDamage;	}	// int KnockbackAmount = 1;	unsigned int PunchLevel = m_CreatorData.m_Enchantments.GetLevel(cEnchantments::enchPunch);	if (PunchLevel > 0)	{		Vector3d LookVector = GetLookVector();		Vector3f FinalSpeed = Vector3f(0, 0, 0);		switch (PunchLevel)		{			case 1: FinalSpeed = LookVector * Vector3d(5, 0.3, 5); break;			case 2: FinalSpeed = LookVector * Vector3d(8, 0.3, 8); break;			default: break;		}		a_EntityHit.SetSpeed(FinalSpeed);	}	// a_EntityHit.TakeDamage(dtRangedAttack, this, Damage, KnockbackAmount);  // TODO fix knockback.	a_EntityHit.TakeDamage(dtRangedAttack, this, Damage, 0);  // Until knockback is fixed.	if (IsOnFire() && !a_EntityHit.IsSubmerged() && !a_EntityHit.IsSwimming())	{		a_EntityHit.StartBurning(100);	}	// Broadcast successful hit sound	GetWorld()->BroadcastSoundEffect("random.successful_hit", GetPosX(), GetPosY(), GetPosZ(), 0.5, static_cast<float>(0.75 + (static_cast<float>((GetUniqueID() * 23) % 32)) / 64));	Destroy();}

static IOReturnPrintSpeedForBSDNode ( const char * bsdNode ){		IOReturn		error			= kIOReturnError;	int 			fileDescriptor	= 0;	UInt16			speed			= 0;	char 			deviceName[MAXPATHLEN];		if ( strncmp ( bsdNode, "/dev/rdisk", 10 ) == 0 )	{		 sprintf ( deviceName, "%s", bsdNode );	}		else if ( strncmp ( bsdNode, "/dev/disk", 9 ) == 0 )	{		sprintf ( deviceName, "%s", bsdNode );	}		else if ( strncmp ( bsdNode, "disk", 4 ) == 0 )	{		sprintf ( deviceName, "%s%s", "/dev/", bsdNode );	}		else	{		goto ErrorExit;	}		fileDescriptor = OpenMedia ( deviceName );	require ( ( fileDescriptor > 0 ), ErrorExit );		speed = GetSpeed ( fileDescriptor );	printf ( "%s: speed = %d KB/s/n", deviceName, speed );		CloseMedia ( fileDescriptor );		ErrorExit:			return error;	}

void CluzookaCluster::DoSpawn(){  const uint fragments = 2;  Double angle;  Double speed;  GetSpeed( speed, angle );  speed = 25;// always  Point2i parent_position = GetPosition();  Double angle_range = QUARTER_PI;  uint rec_depth = 0;#ifdef CLUSTERS_SPAWN_CLUSTERS  rec_depth = m_recursion_depth - 1;#endif  ClusterSpawner< CluzookaCluster >::SpawnClusters( fragments, rec_depth,    parent_position, speed, angle, angle_range, cfg, launcher );}

void cBoat::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk){	super::Tick(a_Dt, a_Chunk);	BroadcastMovementUpdate();	SetSpeed(GetSpeed() * 0.97);  // Slowly decrease the speed	if ((POSY_TOINT < 0) || (POSY_TOINT >= cChunkDef::Height))	{		return;	}	if (IsBlockWater(m_World->GetBlock(POSX_TOINT, POSY_TOINT, POSZ_TOINT)))	{		if (GetSpeedY() < 2)		{			AddSpeedY(0.2);		}	}}

void cArrowEntity::OnHitEntity(cEntity & a_EntityHit, const Vector3d & a_HitPos){	if (!a_EntityHit.IsMob() && !a_EntityHit.IsMinecart() && !a_EntityHit.IsPlayer() && !a_EntityHit.IsBoat())	{		// Not an entity that interacts with an arrow		return;	}		int Damage = (int)(GetSpeed().Length() / 20 * m_DamageCoeff + 0.5);	if (m_IsCritical)	{		Damage += m_World->GetTickRandomNumber(Damage / 2 + 2);	}	a_EntityHit.TakeDamage(dtRangedAttack, this, Damage, 1);		// Broadcast successful hit sound	m_World->BroadcastSoundEffect("random.successful_hit", (int)GetPosX() * 8, (int)GetPosY() * 8, (int)GetPosZ() * 8, 0.5, (float)(0.75 + ((float)((GetUniqueID() * 23) % 32)) / 64));	Destroy();}

dFloat CustomDGRayCastCar::GenerateTiresSteerForce (dFloat value){	dFloat speed, relspeed;	relspeed = dAbs ( GetSpeed() ); 	speed = relspeed;	speed *= m_maxSteerForceRate;	dFloat value2 = value;	if ( speed > m_maxSteerSpeedRestriction ) {		speed = m_maxSteerSpeedRestriction; 	}	if ( value2 > 0.0f ) {		value2 = -( m_maxSteerForce * speed ) * ( 1.0f - relspeed / m_engineSteerDiv );	} else 		if ( value < 0.0f ) {			value2 = ( m_maxSteerForce * speed ) * ( 1.0f - relspeed / m_engineSteerDiv );		} else {			value2 = 0.0f;		}		return value2;}

void CluzookaRocket::DoSpawn(){  const uint fragments = static_cast<CluzookaConfig &>(cfg).m_fragments;  const Double angle_range = static_cast<CluzookaConfig &>(cfg).m_angle_dispersion * PI / (Double)180;  const uint recursion_depth = 0;#ifndef CLUSTERS_SPAWN_CLUSTERS  ASSERT( recursion_depth == 0 );#endif  Double angle;  Double speed;  GetSpeed( speed, angle );  speed = 25;// always  Point2i parent_position = GetPosition();  ClusterSpawner< CluzookaCluster >::SpawnClusters( fragments, recursion_depth,    parent_position, speed, angle, angle_range, cfg, launcher );}

void cArrowEntity::OnHitSolidBlock(const Vector3d & a_HitPos, eBlockFace a_HitFace){	Vector3d Hit = a_HitPos;	Hit += GetSpeed().NormalizeCopy() / 100000;  // Make arrow sink into block a bit so it lodges (TODO: investigate how to stop them going so far so that they become black clientside)	super::OnHitSolidBlock(Hit, a_HitFace);	Vector3i BlockHit = Hit.Floor();	int X = BlockHit.x, Y = BlockHit.y, Z = BlockHit.z;	m_HitBlockPos = Vector3i(X, Y, Z);	// Broadcast arrow hit sound	m_World->BroadcastSoundEffect("random.bowhit", static_cast<double>(X), static_cast<double>(Y), static_cast<double>(Z), 0.5f, static_cast<float>(0.75 + (static_cast<float>((GetUniqueID() * 23) % 32)) / 64));	if ((m_World->GetBlock(Hit) == E_BLOCK_TNT) && IsOnFire())	{		m_World->SetBlock(X, Y, Z, E_BLOCK_AIR, 0);		m_World->SpawnPrimedTNT(X, Y, Z);	}}

bool CCar::SetSpeed(int speed){	if (!IsEngineOn())	{		std::cout << "Couldn't change speed(Engine is off)." << std::endl;		return false;	}	if (GetGear() == 0 && speed > GetSpeed())	{		std::cout << "Couldn't change speed(can't increase speed on 0-gear)." << std::endl;		return false;	}	std::array<int, 2> speedRange = GetSpeedRange(GetGear());	if (speed >= speedRange[0] && speed <= speedRange[1])	{		m_speed = speed;		return true;	}	std::cout << "Couldn't change speed(Your gear does not support this speed)." << std::endl;	return false;}

u32 Army::Troop::GetStrength(void) const{    float res = (GetDamageMin() + GetDamageMax()) >> 1;    // increase strength    if(isFly())		res += res * 0.5;    if(isArchers())	res += res * 0.5;    if(isTwiceAttack())	res += res * 0.5;    if(isHideAttack())	res += res * 0.5;    // slowly: decrease strength    if((!isFly() && !isArchers()) && Speed::AVERAGE > GetSpeed()) res -= res * 0.5;    switch(GetID())    {	case Monster::GHOST: res *= 2; break;	default: break;    }    return static_cast<u32>(res);}

void LocationDlg::UpdateEnabling(){	GetAnimPos()->Enable(m_iAnim != -1);	GetSaveAnim()->Enable(m_iAnim != -1);	GetActive()->Enable(m_iAnim != -1);	GetSpeed()->Enable(m_iAnim != -1);	GetReset()->Enable(m_iAnim != -1);	GetPlay()->Enable(m_iAnim != -1);	GetRecord1()->Enable(m_iAnim != -1);	GetStop()->Enable(m_iAnim != -1);	GetLoop()->Enable(m_iAnim != -1);	GetContinuous()->Enable(m_iAnim != -1);	GetSmooth()->Enable(m_iAnim != -1 && GetAnim(m_iAnim)->NumPoints() > 2);	GetPosOnly()->Enable(m_iAnim != -1);	GetRecordInterval()->Enable(m_iAnim != -1);	GetRecordLinear()->Enable(m_iAnim != -1);	GetRecordSpacing()->Enable(m_bRecordInterval);	GetPlayToDisk()->Enable(m_iAnim != -1);}

void CTriggerPush::Spawn(){	Vector vecAngles = GetAbsAngles();	if( vecAngles == g_vecZero )	{		vecAngles.y = 360;		SetAbsAngles( vecAngles );	}	InitTrigger();	if( GetSpeed() == 0 )		SetSpeed( 100 );	if( GetSpawnFlags().Any( SF_TRIGGER_PUSH_START_OFF ) )// if flagged to Start Turned Off, make trigger nonsolid.		SetSolidType( SOLID_NOT );	SetUse( &CTriggerPush::ToggleUse );	SetAbsOrigin( GetAbsOrigin() );		// Link into the list}

Real SingleCurve3<Real>::GetTime (Real fLength, int iIterations,    Real fTolerance) const{    if (fLength <= (Real)0.0)    {        return m_fTMin;    }    if (fLength >= GetTotalLength())    {        return m_fTMax;    }    // initial guess for Newton's method    Real fRatio = fLength/GetTotalLength();    Real fOmRatio = (Real)1.0 - fRatio;    Real fTime = fOmRatio*m_fTMin + fRatio*m_fTMax;    for (int i = 0; i < iIterations; i++)    {        Real fDifference = GetLength(m_fTMin,fTime) - fLength;        if (Math<Real>::FAbs(fDifference) < fTolerance)        {            return fTime;        }        fTime -= fDifference/GetSpeed(fTime);    }    // Newton's method failed.  You might want to increase iterations or    // tolerance or integration accuracy.  However, in this application it    // is likely that the time values are oscillating, due to the limited    // numerical precision of 32-bit floats.  It is safe to use the last    // computed time.    return fTime;}

void CCruiser::Move(float delta){	switch (mState)	{	case State::Enter:		//Move downwards		mModel->MoveZ(GetSpeed() * -delta);		if (AREA_BOUNDS_TOP - (2.0f * GetRadius()) > mModel->GetZ())		{			mState = State::Rotate;		}		break;	case State::Attack:		break;	case State::Rotate:	{		RotateTowards((*mpPlayers)[0]->GetCenterPoint(), delta * kRotateSpeed);		float bearingToTarget = BearingTowards((*mpPlayers)[0]->GetCenterPoint());		float rotation = GetRotation();		float rotDif = bearingToTarget > rotation ? bearingToTarget - rotation : rotation - bearingToTarget;		if (rotDif < kRotationMargin)		{			mState = State::Attack;			mWeapon->SetFiring(true);			mStateTimer = 0.0f;		}	}		break;	default:		break;	}}

void cMinecart::HandlePhysics(float a_Dt, cChunk & a_Chunk){    if (IsDestroyed())  // Mainly to stop detector rails triggering again after minecart is dead    {        return;    }    int PosY = POSY_TOINT;    if ((PosY <= 0) || (PosY >= cChunkDef::Height))    {        // Outside the world, just process normal falling physics        super::HandlePhysics(a_Dt, a_Chunk);        BroadcastMovementUpdate();        return;    }    int RelPosX = POSX_TOINT - a_Chunk.GetPosX() * cChunkDef::Width;    int RelPosZ = POSZ_TOINT - a_Chunk.GetPosZ() * cChunkDef::Width;    cChunk * Chunk = a_Chunk.GetRelNeighborChunkAdjustCoords(RelPosX, RelPosZ);    if (Chunk == NULL)    {        // Inside an unloaded chunk, bail out all processing        return;    }    BLOCKTYPE InsideType;    NIBBLETYPE InsideMeta;    Chunk->GetBlockTypeMeta(RelPosX, PosY, RelPosZ, InsideType, InsideMeta);    if (!IsBlockRail(InsideType))    {        Chunk->GetBlockTypeMeta(RelPosX, PosY + 1, RelPosZ, InsideType, InsideMeta);  // When an descending minecart hits a flat rail, it goes through the ground; check for this        if (IsBlockRail(InsideType)) AddPosY(1);  // Push cart upwards    }    bool WasDetectorRail = false;    if (IsBlockRail(InsideType))    {        if (InsideType == E_BLOCK_RAIL)        {            SnapToRail(InsideMeta);        }        else        {            SnapToRail(InsideMeta & 0x07);        }        switch (InsideType)        {        case E_BLOCK_RAIL:            HandleRailPhysics(InsideMeta, a_Dt);            break;        case E_BLOCK_ACTIVATOR_RAIL:            break;        case E_BLOCK_POWERED_RAIL:            HandlePoweredRailPhysics(InsideMeta);            break;        case E_BLOCK_DETECTOR_RAIL:        {            HandleDetectorRailPhysics(InsideMeta, a_Dt);            WasDetectorRail = true;            break;        }        default:            VERIFY(!"Unhandled rail type despite checking if block was rail!");            break;        }        AddPosition(GetSpeed() * (a_Dt / 1000));  // Commit changes; as we use our own engine when on rails, this needs to be done, whereas it is normally in Entity.cpp    }    else    {        // Not on rail, default physics        SetPosY(floor(GetPosY()) + 0.35);  // HandlePhysics overrides this if minecart can fall, else, it is to stop ground clipping minecart bottom when off-rail        super::HandlePhysics(a_Dt, *Chunk);    }    if (m_bIsOnDetectorRail && !Vector3i(POSX_TOINT, POSY_TOINT, POSZ_TOINT).Equals(m_DetectorRailPosition))    {        m_World->SetBlock(m_DetectorRailPosition.x, m_DetectorRailPosition.y, m_DetectorRailPosition.z, E_BLOCK_DETECTOR_RAIL, m_World->GetBlockMeta(m_DetectorRailPosition) & 0x07);        m_bIsOnDetectorRail = false;    }    else if (WasDetectorRail)    {        m_bIsOnDetectorRail = true;        m_DetectorRailPosition = Vector3i(POSX_TOINT, POSY_TOINT, POSZ_TOINT);    }    // Broadcast positioning changes to client    BroadcastMovementUpdate();}

// Move to a point with collision testcollision_t PhysicalObj::NotifyMove(Point2d oldPos, Point2d newPos){  if (IsGhost())    return NO_COLLISION;  Point2d contactPos;  Double contactAngle;  Point2d pos, offset;  PhysicalObj* collided_obj = NULL;  collision_t collision = NO_COLLISION;  // Convert meters to pixels.  oldPos *= PIXEL_PER_METER;  newPos *= PIXEL_PER_METER;  // Compute distance between old and new position.  Double lg = oldPos.SquareDistance(newPos);  MSG_DEBUG("physic.move", "%s moves (%s, %s) -> (%s, %s), square distance: %s",            GetName().c_str(),            Double2str(oldPos.x).c_str(), Double2str(oldPos.y).c_str(),            Double2str(newPos.x).c_str(), Double2str(newPos.y).c_str(),            Double2str(lg).c_str());  if (!lg.IsNotZero())    return NO_COLLISION;  // Compute increments to move the object step by step from the old  // to the new position.  lg = sqrt(lg);  offset = (newPos - oldPos) / lg;  // First iteration position.  pos = oldPos + offset;  if (!m_collides_with_ground || IsInWater()) {    MSG_DEBUG("physic.move", "%s moves (%s, %s) -> (%s, %s), collides ground:%d, water:%d",              GetName().c_str(),              Double2str(oldPos.x).c_str(), Double2str(oldPos.y).c_str(),              Double2str(newPos.x).c_str(), Double2str(newPos.y).c_str(),              m_collides_with_ground, IsInWater());    SetXY(newPos);    return NO_COLLISION;  }  do {    Point2i tmpPos(uround(pos.x), uround(pos.y));    // Check if we exit the GetWorld(). If so, we stop moving and return.    if (IsOutsideWorldXY(tmpPos)) {      if (!GetWorld().IsOpen()) {        tmpPos.x = InRange_Long(tmpPos.x, 0, GetWorld().GetWidth() - GetWidth() - 1);        tmpPos.y = InRange_Long(tmpPos.y, 0, GetWorld().GetHeight() - GetHeight() - 1);        MSG_DEBUG("physic.state", "%s - DeplaceTestCollision touche un bord : %d, %d",                  GetName().c_str(), tmpPos.x, tmpPos.y);        collision = COLLISION_ON_GROUND;        break;      }      SetXY(pos);      MSG_DEBUG("physic.move", "%s moves (%f, %f) -> (%f, %f) : OUTSIDE WORLD",                GetName().c_str(), oldPos.x.tofloat(), oldPos.y.tofloat(),                newPos.x.tofloat(), newPos.y.tofloat());      return NO_COLLISION;    }    // Test if we collide...    collided_obj = CollidedObjectXY(tmpPos);    if (collided_obj) {      if (!m_go_through_objects || m_last_collided_object != collided_obj) {        MSG_DEBUG("physic.state", "%s collide on %s", GetName().c_str(), collided_obj->GetName().c_str());        if (m_go_through_objects) {          SignalObjectCollision(GetSpeed(), collided_obj, collided_obj->GetSpeed());          collision = NO_COLLISION;        } else {          collision = COLLISION_ON_OBJECT;        }        m_last_collided_object = collided_obj;      } else {        collided_obj = NULL;        collision = NO_COLLISION;      }    } else if (!IsInVacuumXY(tmpPos, false)) {      collision = COLLISION_ON_GROUND;      m_last_collided_object = NULL;    }    if (collision != NO_COLLISION) {      // Nothing more to do!      MSG_DEBUG("physic.state", "%s - Collision at %d,%d : on %s",                GetName().c_str(), tmpPos.x, tmpPos.y,                collision == COLLISION_ON_GROUND ? "ground" : "an object");      // Set the object position to the current position.//.........这里部分代码省略.........