/** 
 * @file llfollowcam.cpp
 * @author Jeffrey Ventrella
 * @brief LLFollowCam class implementation
 *
 * $LicenseInfo:firstyear=2005&license=viewergpl$
 * 
 * Copyright (c) 2005-2008, Linden Research, Inc.
 * 
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 * 
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/flossexception
 * 
 * By copying, modifying or distributing this software, you acknowledge
 * that you have read and understood your obligations described above,
 * and agree to abide by those obligations.
 * 
 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
 * COMPLETENESS OR PERFORMANCE.
 * $/LicenseInfo$
 */

#include "llviewerprecompiledheaders.h"
#include "llfollowcam.h"
#include "llagent.h"

//-------------------------------------------------------
// class statics
//-------------------------------------------------------
std::map<LLUUID, LLFollowCamParams*> LLFollowCamMgr::sParamMap;
std::vector<LLFollowCamParams*> LLFollowCamMgr::sParamStack;

//-------------------------------------------------------
// constants
//-------------------------------------------------------
const F32 ONE_HALF							= 0.5; 
const F32 FOLLOW_CAM_ZOOM_FACTOR			= 0.1f;
const F32 FOLLOW_CAM_MIN_ZOOM_AMOUNT		= 0.1f;
const F32 DISTANCE_EPSILON					= 0.0001f;
const F32 DEFAULT_MAX_DISTANCE_FROM_SUBJECT	= 1000.0;	// this will be correctly set on me by my caller

//----------------------------------------------------------------------------------------
// This is how slowly the camera position moves to its ideal position 
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_POSITION_LAG		= 0.0f;		
const F32 FOLLOW_CAM_DEFAULT_POSITION_LAG	= 0.1f;  
const F32 FOLLOW_CAM_MAX_POSITION_LAG		= 3.0f;

//----------------------------------------------------------------------------------------
// This is how slowly the camera focus moves to its subject
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_FOCUS_LAG		= 0.0f;
const F32 FOLLOW_CAM_DEFAULT_FOCUS_LAG	= 0.1f;
const F32 FOLLOW_CAM_MAX_FOCUS_LAG		= 3.0f;

//----------------------------------------------------------------------------------------
// This is far the position can get from its IDEAL POSITION before it starts getting pulled
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_POSITION_THRESHOLD		= 0.0f;
const F32 FOLLOW_CAM_DEFAULT_POSITION_THRESHOLD	= 1.0f;
const F32 FOLLOW_CAM_MAX_POSITION_THRESHOLD		= 4.0f;

//----------------------------------------------------------------------------------------
// This is far the focus can get from the subject before it starts getting pulled
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_FOCUS_THRESHOLD		= 0.0f;
const F32 FOLLOW_CAM_DEFAULT_FOCUS_THRESHOLD	= 1.0f;
const F32 FOLLOW_CAM_MAX_FOCUS_THRESHOLD		= 4.0f;

//----------------------------------------------------------------------------------------
// This is the distance the camera wants to be from the subject
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_DISTANCE		= 0.5f;
const F32 FOLLOW_CAM_DEFAULT_DISTANCE	= 3.0f;
//const F32 FOLLOW_CAM_MAX_DISTANCE		= 10.0f; // from now on I am using mMaxCameraDistantFromSubject

//----------------------------------------------------------------------------------------
// this is an angluar value
// It affects the angle that the camera rises (pitches) in relation 
// to the horizontal plane
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_PITCH		= -45.0f; 
const F32 FOLLOW_CAM_DEFAULT_PITCH	=   0.0f;
const F32 FOLLOW_CAM_MAX_PITCH		=  80.0f;	// keep under 90 degrees - avoid gimble lock!


//----------------------------------------------------------------------------------------
// how high or low the camera considers its ideal focus to be (relative to its subject)
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_FOCUS_OFFSET		= -10.0f;
const LLVector3 FOLLOW_CAM_DEFAULT_FOCUS_OFFSET	=  LLVector3(1.0f, 0.f, 0.f);
const F32 FOLLOW_CAM_MAX_FOCUS_OFFSET		=  10.0f;

//----------------------------------------------------------------------------------------
// This affects the rate at which the camera adjusts to stay behind the subject
//----------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_BEHINDNESS_LAG		= 0.0f;
const F32 FOLLOW_CAM_DEFAULT_BEHINDNESS_LAG		= 0.f;
const F32 FOLLOW_CAM_MAX_BEHINDNESS_LAG		= 3.0f;

//---------------------------------------------------------------------------------------------------------------------
// in  degrees: This is the size of the pie slice behind the subject matter within which the camera is free to move
//---------------------------------------------------------------------------------------------------------------------
const F32 FOLLOW_CAM_MIN_BEHINDNESS_ANGLE		= 0.0f;
const F32 FOLLOW_CAM_DEFAULT_BEHINDNESS_ANGLE	= 10.0f;
const F32 FOLLOW_CAM_MAX_BEHINDNESS_ANGLE		= 180.0f;
const F32 FOLLOW_CAM_BEHINDNESS_EPSILON			= 1.0f;

//------------------------------------
// Constructor
//------------------------------------
LLFollowCamParams::LLFollowCamParams()
{
	mMaxCameraDistantFromSubject		= DEFAULT_MAX_DISTANCE_FROM_SUBJECT;
	mPositionLocked						= false;
	mFocusLocked						= false;
	mUsePosition						= false;
	mUseFocus							= false;

	//------------------------------------------------------
	// setting the attributes to their defaults
	//------------------------------------------------------
	setPositionLag		( FOLLOW_CAM_DEFAULT_POSITION_LAG			);
	setFocusLag			( FOLLOW_CAM_DEFAULT_FOCUS_LAG				);
	setPositionThreshold( FOLLOW_CAM_DEFAULT_POSITION_THRESHOLD		);
	setFocusThreshold	( FOLLOW_CAM_DEFAULT_FOCUS_THRESHOLD		);
	setBehindnessLag	( FOLLOW_CAM_DEFAULT_BEHINDNESS_LAG		);
	setDistance			( FOLLOW_CAM_DEFAULT_DISTANCE				);
	setPitch			( FOLLOW_CAM_DEFAULT_PITCH					);
	setFocusOffset		( FOLLOW_CAM_DEFAULT_FOCUS_OFFSET	);
	setBehindnessAngle	( FOLLOW_CAM_DEFAULT_BEHINDNESS_ANGLE		);
	setPositionThreshold( FOLLOW_CAM_DEFAULT_POSITION_THRESHOLD		);
	setFocusThreshold	( FOLLOW_CAM_DEFAULT_FOCUS_THRESHOLD		);

}

LLFollowCamParams::~LLFollowCamParams() { }

//---------------------------------------------------------
// buncho set methods
//---------------------------------------------------------

//---------------------------------------------------------
void LLFollowCamParams::setPositionLag( F32 p ) 
{ 
	mPositionLag = llclamp(p, FOLLOW_CAM_MIN_POSITION_LAG, FOLLOW_CAM_MAX_POSITION_LAG); 
}


//---------------------------------------------------------
void LLFollowCamParams::setFocusLag( F32 f ) 
{ 
	mFocusLag = llclamp(f, FOLLOW_CAM_MIN_FOCUS_LAG, FOLLOW_CAM_MAX_FOCUS_LAG); 
}


//---------------------------------------------------------
void LLFollowCamParams::setPositionThreshold( F32 p ) 
{ 
	mPositionThreshold = llclamp(p, FOLLOW_CAM_MIN_POSITION_THRESHOLD, FOLLOW_CAM_MAX_POSITION_THRESHOLD); 
}


//---------------------------------------------------------
void LLFollowCamParams::setFocusThreshold( F32 f ) 
{ 
	mFocusThreshold = llclamp(f, FOLLOW_CAM_MIN_FOCUS_THRESHOLD, FOLLOW_CAM_MAX_FOCUS_THRESHOLD); 
}


//---------------------------------------------------------
void LLFollowCamParams::setPitch( F32 p ) 
{ 
	mPitch = llclamp(p, FOLLOW_CAM_MIN_PITCH, FOLLOW_CAM_MAX_PITCH); 
}


//---------------------------------------------------------
void LLFollowCamParams::setBehindnessLag( F32 b ) 
{ 
	mBehindnessLag = llclamp(b, FOLLOW_CAM_MIN_BEHINDNESS_LAG, FOLLOW_CAM_MAX_BEHINDNESS_LAG); 
}

//---------------------------------------------------------
void LLFollowCamParams::setBehindnessAngle( F32 b ) 
{ 
	mBehindnessMaxAngle = llclamp(b, FOLLOW_CAM_MIN_BEHINDNESS_ANGLE, FOLLOW_CAM_MAX_BEHINDNESS_ANGLE); 
}

//---------------------------------------------------------
void LLFollowCamParams::setDistance( F32 d ) 
{ 
	mDistance = llclamp(d, FOLLOW_CAM_MIN_DISTANCE, mMaxCameraDistantFromSubject); 
}

//---------------------------------------------------------
void LLFollowCamParams::setPositionLocked( bool l ) 
{
	mPositionLocked = l;
}

//---------------------------------------------------------
void LLFollowCamParams::setFocusLocked( bool l ) 
{
	mFocusLocked = l;

}

//---------------------------------------------------------
void LLFollowCamParams::setFocusOffset( const LLVector3& v ) 
{ 
	mFocusOffset = v; 
	mFocusOffset.clamp(FOLLOW_CAM_MIN_FOCUS_OFFSET, FOLLOW_CAM_MAX_FOCUS_OFFSET);
}

//---------------------------------------------------------
void LLFollowCamParams::setPosition( const LLVector3& p ) 
{ 
	mUsePosition = true;
	mPosition = p;
}

//---------------------------------------------------------
void LLFollowCamParams::setFocus( const LLVector3& f ) 
{ 
	mUseFocus = true;
	mFocus = f;
}

//---------------------------------------------------------
// buncho get methods
//---------------------------------------------------------
F32			LLFollowCamParams::getPositionLag		() const { return mPositionLag;			}
F32			LLFollowCamParams::getFocusLag			() const { return mFocusLag;			}
F32			LLFollowCamParams::getPositionThreshold	() const { return mPositionThreshold;	}
F32			LLFollowCamParams::getFocusThreshold	() const { return mFocusThreshold;		}
F32			LLFollowCamParams::getDistance			() const { return mDistance;			}
F32			LLFollowCamParams::getPitch				() const { return mPitch;				}
LLVector3	LLFollowCamParams::getFocusOffset		() const { return mFocusOffset;			}
F32			LLFollowCamParams::getBehindnessAngle	() const { return mBehindnessMaxAngle;	}
F32			LLFollowCamParams::getBehindnessLag		() const { return mBehindnessLag;		}
LLVector3	LLFollowCamParams::getPosition			() const { return mPosition;			}
LLVector3	LLFollowCamParams::getFocus				() const { return mFocus;				}
bool		LLFollowCamParams::getPositionLocked	() const { return mPositionLocked;		}
bool		LLFollowCamParams::getFocusLocked		() const { return mFocusLocked;			}

//------------------------------------
// Constructor
//------------------------------------
LLFollowCam::LLFollowCam() : LLFollowCamParams()
{
	mUpVector							= LLVector3::z_axis;
	mSubjectPosition					= LLVector3::zero;
	mSubjectRotation					= LLQuaternion::DEFAULT;

	mZoomedToMinimumDistance			= false;
	mPitchCos = mPitchSin = 0.f;
	mPitchSineAndCosineNeedToBeUpdated	= true; 

	mSimulatedDistance = mDistance;
}

void LLFollowCam::copyParams(LLFollowCamParams& params)
{
	setPositionLag(params.getPositionLag());
	setFocusLag(params.getFocusLag());
	setFocusThreshold( params.getFocusThreshold());
	setPositionThreshold(params.getPositionThreshold());
	setPitch(params.getPitch());
	setFocusOffset(params.getFocusOffset());
	setBehindnessAngle(params.getBehindnessAngle());
	setBehindnessLag(params.getBehindnessLag());

	setPositionLocked(params.getPositionLocked());
	setFocusLocked(params.getFocusLocked());

	setDistance(params.getDistance());	
	if (params.getUsePosition())
	{
		setPosition(params.getPosition());
	}
	if (params.getUseFocus())
	{
		setFocus(params.getFocus());
	}
}

//---------------------------------------------------------------------------------------------------------
void LLFollowCam::update()
{
	//####################################################################################
	// update Focus
	//####################################################################################
	LLVector3 offsetSubjectPosition = mSubjectPosition + (mFocusOffset * mSubjectRotation);

	LLVector3 simulated_pos_agent = gAgent.getPosAgentFromGlobal(mSimulatedPositionGlobal);
	LLVector3 vectorFromCameraToSubject = offsetSubjectPosition - simulated_pos_agent;
	F32 distanceFromCameraToSubject = vectorFromCameraToSubject.magVec();

	LLVector3 whereFocusWantsToBe = mFocus;
	LLVector3 focus_pt_agent = gAgent.getPosAgentFromGlobal(mSimulatedFocusGlobal);
	if ( mFocusLocked ) // if focus is locked, only relative focus needs to be updated
	{
		mRelativeFocus = (focus_pt_agent - mSubjectPosition) * ~mSubjectRotation;
	}
	else
	{
		LLVector3 focusOffset = offsetSubjectPosition - focus_pt_agent;
		F32 focusOffsetDistance = focusOffset.magVec();

		LLVector3 focusOffsetDirection = focusOffset / focusOffsetDistance;
		whereFocusWantsToBe = focus_pt_agent + 
			(focusOffsetDirection * (focusOffsetDistance - mFocusThreshold));
		if ( focusOffsetDistance > mFocusThreshold )
		{
			// this version normalizes focus threshold by distance 
			// so that the effect is not changed with distance
			/*
			F32 focusThresholdNormalizedByDistance = distanceFromCameraToSubject * mFocusThreshold;
			if ( focusOffsetDistance > focusThresholdNormalizedByDistance )
			{
				LLVector3 focusOffsetDirection = focusOffset / focusOffsetDistance;
				F32 force = focusOffsetDistance - focusThresholdNormalizedByDistance;
			*/

			F32 focusLagLerp = LLCriticalDamp::getInterpolant( mFocusLag );
			focus_pt_agent = lerp( focus_pt_agent, whereFocusWantsToBe, focusLagLerp );
			mSimulatedFocusGlobal = gAgent.getPosGlobalFromAgent(focus_pt_agent);
		}
		mRelativeFocus = lerp(mRelativeFocus, (focus_pt_agent - mSubjectPosition) * ~mSubjectRotation, LLCriticalDamp::getInterpolant(0.05f));
	}// if focus is not locked ---------------------------------------------


	LLVector3 whereCameraPositionWantsToBe = gAgent.getPosAgentFromGlobal(mSimulatedPositionGlobal);
	if (  mPositionLocked )
	{
		mRelativePos = (whereCameraPositionWantsToBe - mSubjectPosition) * ~mSubjectRotation;
	}
	else
	{
		//####################################################################################
		// update Position
		//####################################################################################
		//-------------------------------------------------------------------------
		// I determine the horizontal vector from the camera to the subject
		//-------------------------------------------------------------------------
		LLVector3 horizontalVectorFromCameraToSubject = vectorFromCameraToSubject;
		horizontalVectorFromCameraToSubject.mV[VZ] = 0.0f;

		//---------------------------------------------------------
		// Now I determine the horizontal distance
		//---------------------------------------------------------
		F32 horizontalDistanceFromCameraToSubject = horizontalVectorFromCameraToSubject.magVec();  

		//---------------------------------------------------------
		// Then I get the (normalized) horizontal direction...
		//---------------------------------------------------------
		LLVector3 horizontalDirectionFromCameraToSubject;	
		if ( horizontalDistanceFromCameraToSubject < DISTANCE_EPSILON )
		{
			// make sure we still have a normalized vector if distance is really small 
			// (this case is rare and fleeting)
			horizontalDirectionFromCameraToSubject = LLVector3::z_axis;
		}
		else
		{
			// I'm not using the "normalize" method, because I can just divide by horizontalDistanceFromCameraToSubject
			horizontalDirectionFromCameraToSubject = horizontalVectorFromCameraToSubject / horizontalDistanceFromCameraToSubject;
		}

		//------------------------------------------------------------------------------------------------------------
		// Here is where I determine an offset relative to subject position in oder to set the ideal position. 
		//------------------------------------------------------------------------------------------------------------
		if ( mPitchSineAndCosineNeedToBeUpdated )
		{
			calculatePitchSineAndCosine();
			mPitchSineAndCosineNeedToBeUpdated = false;
		}

		LLVector3 positionOffsetFromSubject;
		positionOffsetFromSubject.setVec
			( 
				horizontalDirectionFromCameraToSubject.mV[ VX ] * mPitchCos,
				horizontalDirectionFromCameraToSubject.mV[ VY ] * mPitchCos,
				-mPitchSin
			);

		positionOffsetFromSubject *= mSimulatedDistance;

		//----------------------------------------------------------------------
		// Finally, ideal position is set by taking the subject position and 
		// extending the positionOffsetFromSubject from that
		//----------------------------------------------------------------------
		LLVector3 idealCameraPosition = offsetSubjectPosition - positionOffsetFromSubject;

		//--------------------------------------------------------------------------------
		// Now I prepare to move the current camera position towards its ideal position...
		//--------------------------------------------------------------------------------
		LLVector3 vectorFromPositionToIdealPosition = idealCameraPosition - simulated_pos_agent;
		F32 distanceFromPositionToIdealPosition = vectorFromPositionToIdealPosition.magVec();
		
		//put this inside of the block?		
		LLVector3 normalFromPositionToIdealPosition = vectorFromPositionToIdealPosition / distanceFromPositionToIdealPosition;
		
		whereCameraPositionWantsToBe = simulated_pos_agent + 
			(normalFromPositionToIdealPosition * (distanceFromPositionToIdealPosition - mPositionThreshold));
		//-------------------------------------------------------------------------------------------------
		// The following method takes the target camera position and resets it so that it stays "behind" the subject, 
		// using behindness angle and behindness force as parameters affecting the exact behavior
		//-------------------------------------------------------------------------------------------------
		if ( distanceFromPositionToIdealPosition > mPositionThreshold )
		{
			F32 positionPullLerp = LLCriticalDamp::getInterpolant( mPositionLag );
			simulated_pos_agent = lerp( simulated_pos_agent, whereCameraPositionWantsToBe, positionPullLerp );
		}

		//--------------------------------------------------------------------
		// don't let the camera get farther than its official max distance
		//--------------------------------------------------------------------
		if ( distanceFromCameraToSubject > mMaxCameraDistantFromSubject )
		{
			LLVector3 directionFromCameraToSubject = vectorFromCameraToSubject / distanceFromCameraToSubject;
			simulated_pos_agent = offsetSubjectPosition - directionFromCameraToSubject * mMaxCameraDistantFromSubject;
		}

		////-------------------------------------------------------------------------------------------------
		//// The following method takes mSimulatedPositionGlobal and resets it so that it stays "behind" the subject, 
		//// using behindness angle and behindness force as parameters affecting the exact behavior
		////-------------------------------------------------------------------------------------------------
		updateBehindnessConstraint(gAgent.getPosAgentFromGlobal(mSimulatedFocusGlobal), simulated_pos_agent);
		mSimulatedPositionGlobal = gAgent.getPosGlobalFromAgent(simulated_pos_agent);

		mRelativePos = lerp(mRelativePos, (simulated_pos_agent - mSubjectPosition) * ~mSubjectRotation, LLCriticalDamp::getInterpolant(0.05f));
	} // if position is not locked -----------------------------------------------------------


	//####################################################################################
	// update UpVector
	//####################################################################################
	// this just points upward for now, but I anticipate future effects requiring 
	// some rolling ("banking" effects for fun, swoopy vehicles, etc.)
	mUpVector = LLVector3::z_axis;
}



//-------------------------------------------------------------------------------------
BOOL LLFollowCam::updateBehindnessConstraint(LLVector3 focus, LLVector3& cam_position)
{
	BOOL constraint_active = FALSE;
	// only apply this stuff if the behindness angle is something other than opened up all the way
	if ( mBehindnessMaxAngle < FOLLOW_CAM_MAX_BEHINDNESS_ANGLE - FOLLOW_CAM_BEHINDNESS_EPSILON )
	{
		//--------------------------------------------------------------
		// horizontalized vector from focus to camera 
		//--------------------------------------------------------------
		LLVector3 horizontalVectorFromFocusToCamera;
		horizontalVectorFromFocusToCamera.setVec(cam_position - focus);
		horizontalVectorFromFocusToCamera.mV[ VZ ] = 0.0f; 
		F32 cameraZ = cam_position.mV[ VZ ];

		//--------------------------------------------------------------
		// distance of horizontalized vector
		//--------------------------------------------------------------
		F32 horizontalDistance = horizontalVectorFromFocusToCamera.magVec();

		//--------------------------------------------------------------------------------------------------
		// calculate horizontalized back vector of the subject and scale by horizontalDistance
		//--------------------------------------------------------------------------------------------------
		LLVector3 horizontalSubjectBack( -1.0f, 0.0f, 0.0f );
		horizontalSubjectBack *= mSubjectRotation;
		horizontalSubjectBack.mV[ VZ ] = 0.0f; 
		horizontalSubjectBack.normVec(); // because horizontalizing might make it shorter than 1
		horizontalSubjectBack *= horizontalDistance;

		//--------------------------------------------------------------------------------------------------
		// find the angle (in degrees) between these vectors
		//--------------------------------------------------------------------------------------------------
		F32 cameraOffsetAngle = 0.f;
		LLVector3 cameraOffsetRotationAxis;
		LLQuaternion camera_offset_rotation;
		camera_offset_rotation.shortestArc(horizontalSubjectBack, horizontalVectorFromFocusToCamera);
		camera_offset_rotation.getAngleAxis(&cameraOffsetAngle, cameraOffsetRotationAxis);
		cameraOffsetAngle *= RAD_TO_DEG;

		if ( cameraOffsetAngle > mBehindnessMaxAngle )
		{
			F32 fraction = ((cameraOffsetAngle - mBehindnessMaxAngle) / cameraOffsetAngle) * LLCriticalDamp::getInterpolant(mBehindnessLag);
			cam_position = focus + horizontalSubjectBack * (slerp(fraction, camera_offset_rotation, LLQuaternion::DEFAULT));
			cam_position.mV[VZ] = cameraZ; // clamp z value back to what it was before we started messing with it
			constraint_active = TRUE;
		}
	}
	return constraint_active;
}


//---------------------------------------------------------
void LLFollowCam::calculatePitchSineAndCosine()
{
	F32 radian = mPitch * DEG_TO_RAD;
	mPitchCos = cos( radian );
	mPitchSin = sin( radian );
}

//---------------------------------------------------------
void LLFollowCam::setSubjectPositionAndRotation( const LLVector3 p, const LLQuaternion r )
{
	mSubjectPosition = p;
	mSubjectRotation = r;
}


//---------------------------------------------------------
void LLFollowCam::zoom( S32 z ) 
{ 
	F32 zoomAmount = z * mSimulatedDistance * FOLLOW_CAM_ZOOM_FACTOR;

	if (( zoomAmount <  FOLLOW_CAM_MIN_ZOOM_AMOUNT )
	&&  ( zoomAmount > -FOLLOW_CAM_MIN_ZOOM_AMOUNT ))
	{
		if ( zoomAmount < 0.0f )
		{
			zoomAmount = -FOLLOW_CAM_MIN_ZOOM_AMOUNT;
		}
		else
		{
			zoomAmount = FOLLOW_CAM_MIN_ZOOM_AMOUNT;
		}
	}

	mSimulatedDistance += zoomAmount;

	mZoomedToMinimumDistance = false;
	if ( mSimulatedDistance < FOLLOW_CAM_MIN_DISTANCE ) 
	{
		mSimulatedDistance = FOLLOW_CAM_MIN_DISTANCE;

		// if zoomAmount is negative (i.e., getting closer), then
		// this signifies having hit the minimum:
		if ( zoomAmount < 0.0f )
		{
			mZoomedToMinimumDistance = true;
		}
	}
	else if ( mSimulatedDistance > mMaxCameraDistantFromSubject ) 
	{
		mSimulatedDistance = mMaxCameraDistantFromSubject;
	}
}


//---------------------------------------------------------
bool LLFollowCam::isZoomedToMinimumDistance()
{
	return mZoomedToMinimumDistance;
}


//---------------------------------------------------------
void LLFollowCam::reset( const LLVector3 p, const LLVector3 f , const LLVector3 u )
{
	setPosition(p);
	setFocus(f);
	mUpVector	= u;
}

//---------------------------------------------------------
void LLFollowCam::setMaxCameraDistantFromSubject( F32 m )
{
	mMaxCameraDistantFromSubject = m;
}


void LLFollowCam::setPitch( F32 p ) 
{ 
	LLFollowCamParams::setPitch(p);
	mPitchSineAndCosineNeedToBeUpdated = true; // important
}

void LLFollowCam::setDistance( F32 d ) 
{ 
	if (d != mDistance)
	{
		LLFollowCamParams::setDistance(d);
		mSimulatedDistance = d;
		mZoomedToMinimumDistance = false; 
	}
}

void LLFollowCam::setPosition( const LLVector3& p ) 
{ 
	if (p != mPosition)
	{
		LLFollowCamParams::setPosition(p);
		mSimulatedPositionGlobal = gAgent.getPosGlobalFromAgent(mPosition);
		if (mPositionLocked)
		{
			mRelativePos = (mPosition - mSubjectPosition) * ~mSubjectRotation;
		}
	}
}

void LLFollowCam::setFocus( const LLVector3& f ) 
{ 
	if (f != mFocus)
	{
		LLFollowCamParams::setFocus(f);
		mSimulatedFocusGlobal = gAgent.getPosGlobalFromAgent(f);
		if (mFocusLocked)
		{
			mRelativeFocus = (mFocus - mSubjectPosition) * ~mSubjectRotation;
		}
	}
}

void LLFollowCam::setPositionLocked( bool locked )
{
	LLFollowCamParams::setPositionLocked(locked);
	if (locked)
	{
		// propagate set position to relative position
		mRelativePos = (gAgent.getPosAgentFromGlobal(mSimulatedPositionGlobal) - mSubjectPosition) * ~mSubjectRotation;
	}
}

void LLFollowCam::setFocusLocked( bool locked )
{
	LLFollowCamParams::setFocusLocked(locked);
	if (locked)	
	{
		// propagate set position to relative position
		mRelativeFocus = (gAgent.getPosAgentFromGlobal(mSimulatedFocusGlobal) - mSubjectPosition) * ~mSubjectRotation;
	}
}


LLVector3	LLFollowCam::getSimulatedPosition() const 
{ 
	// return simulated position
	return mSubjectPosition + (mRelativePos * mSubjectRotation);
}

LLVector3	LLFollowCam::getSimulatedFocus() const 
{ 
	// return simulated focus point
	return mSubjectPosition + (mRelativeFocus * mSubjectRotation);
}

LLVector3	LLFollowCam::getUpVector() 
{ 
	return mUpVector;			
}


//------------------------------------
// Destructor
//------------------------------------
LLFollowCam::~LLFollowCam()
{
}


//-------------------------------------------------------
// LLFollowCamMgr
//-------------------------------------------------------
//static
void LLFollowCamMgr::cleanupClass()
{
	for (param_map_t::iterator iter = sParamMap.begin(); iter != sParamMap.end(); ++iter)
	{
		LLFollowCamParams* params = iter->second;
		delete params;
	}
	sParamMap.clear();
}

//static
void LLFollowCamMgr::setPositionLag( const LLUUID& source, F32 lag)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setPositionLag(lag);
	}
}

//static
void LLFollowCamMgr::setFocusLag( const LLUUID& source, F32 lag)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setFocusLag(lag);
	}
}

//static
void LLFollowCamMgr::setFocusThreshold( const LLUUID& source, F32 threshold)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setFocusThreshold(threshold);
	}

}

//static
void LLFollowCamMgr::setPositionThreshold( const LLUUID& source, F32 threshold)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setPositionThreshold(threshold);
	}
}

//static
void LLFollowCamMgr::setDistance( const LLUUID& source, F32 distance)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setDistance(distance);
	}
}

//static
void LLFollowCamMgr::setPitch( const LLUUID& source, F32 pitch)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setPitch(pitch);
	}
}

//static
void LLFollowCamMgr::setFocusOffset( const LLUUID& source, const LLVector3& offset)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setFocusOffset(offset);
	}
}

//static
void LLFollowCamMgr::setBehindnessAngle( const LLUUID& source, F32 angle)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setBehindnessAngle(angle);
	}
}

//static
void LLFollowCamMgr::setBehindnessLag( const LLUUID& source, F32 force)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setBehindnessLag(force);
	}
}

//static
void LLFollowCamMgr::setPosition( const LLUUID& source, const LLVector3 position)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setPosition(position);
	}
}

//static
void LLFollowCamMgr::setFocus( const LLUUID& source, const LLVector3 focus)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setFocus(focus);
	}
}

//static
void LLFollowCamMgr::setPositionLocked( const LLUUID& source, bool locked)
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setPositionLocked(locked);
	}
}

//static
void LLFollowCamMgr::setFocusLocked( const LLUUID& source, bool locked )
{
	LLFollowCamParams* paramsp = getParamsForID(source);
	if (paramsp)
	{
		paramsp->setFocusLocked(locked);
	}
}

//static 
LLFollowCamParams* LLFollowCamMgr::getParamsForID(const LLUUID& source)
{
	LLFollowCamParams* params = NULL;

	param_map_t::iterator found_it = sParamMap.find(source);
	if (found_it == sParamMap.end()) // didn't find it?
	{
		params = new LLFollowCamParams();
		sParamMap[source] = params;
	}
	else
	{
		params = found_it->second;
	}

	return params;
}

//static
LLFollowCamParams* LLFollowCamMgr::getActiveFollowCamParams()
{
	if (sParamStack.empty())
	{
		return NULL;
	}

	return sParamStack.back();
}

//static 
void LLFollowCamMgr::setCameraActive( const LLUUID& source, bool active )
{
	LLFollowCamParams* params = getParamsForID(source);
	param_stack_t::iterator found_it = std::find(sParamStack.begin(), sParamStack.end(), params);
	if (found_it != sParamStack.end())
	{
		sParamStack.erase(found_it);
	}
	// put on top of stack
	if(active)
	{
		sParamStack.push_back(params);
	}
}

//static
void LLFollowCamMgr::removeFollowCamParams(const LLUUID& source)
{
	setCameraActive(source, FALSE);
	LLFollowCamParams* params = getParamsForID(source);
	sParamMap.erase(source);
	delete params;
}

//static
bool LLFollowCamMgr::isScriptedCameraSource(const LLUUID& source)
{
	param_map_t::iterator found_it = sParamMap.find(source);
	return (found_it != sParamMap.end());
}

//static 
void LLFollowCamMgr::dump()
{
	S32 param_count = 0;
	llinfos << "Scripted camera active stack" << llendl;
	for (param_stack_t::iterator param_it = sParamStack.begin();
		param_it != sParamStack.end();
		++param_it)
	{
		llinfos << param_count++ << 
			" rot_limit: " << (*param_it)->getBehindnessAngle() << 
			" rot_lag: " << (*param_it)->getBehindnessLag() << 
			" distance: " << (*param_it)->getDistance() << 
			" focus: " << (*param_it)->getFocus() << 
			" foc_lag: " << (*param_it)->getFocusLag() << 
			" foc_lock: " << ((*param_it)->getFocusLocked() ? "Y" : "N") << 
			" foc_offset: " << (*param_it)->getFocusOffset() << 
			" foc_thresh: " << (*param_it)->getFocusThreshold() << 
			" pitch: " << (*param_it)->getPitch() << 
			" pos: " << (*param_it)->getPosition() << 
			" pos_lag: " << (*param_it)->getPositionLag() << 
			" pos_lock: " << ((*param_it)->getPositionLocked() ? "Y" : "N") << 
			" pos_thresh: " << (*param_it)->getPositionThreshold() << llendl;
	}
}