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/**
* @file llcriticaldamp.cpp
* @brief Implementation of the critical damping functionality.
*
* Copyright (c) 2002-2007, 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://secondlife.com/developers/opensource/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://secondlife.com/developers/opensource/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.
*/
#include "linden_common.h"
#include <math.h>
#include "llcriticaldamp.h"
//-----------------------------------------------------------------------------
// static members
//-----------------------------------------------------------------------------
LLFrameTimer LLCriticalDamp::sInternalTimer;
std::map<F32, F32> LLCriticalDamp::sInterpolants;
F32 LLCriticalDamp::sTimeDelta;
//-----------------------------------------------------------------------------
// LLCriticalDamp()
//-----------------------------------------------------------------------------
LLCriticalDamp::LLCriticalDamp()
{
sTimeDelta = 0.f;
}
// static
//-----------------------------------------------------------------------------
// updateInterpolants()
//-----------------------------------------------------------------------------
void LLCriticalDamp::updateInterpolants()
{
sTimeDelta = sInternalTimer.getElapsedTimeAndResetF32();
F32 time_constant;
for (std::map<F32, F32>::iterator iter = sInterpolants.begin();
iter != sInterpolants.end(); iter++)
{
time_constant = iter->first;
F32 new_interpolant = 1.f - pow(2.f, -sTimeDelta / time_constant);
new_interpolant = llclamp(new_interpolant, 0.f, 1.f);
sInterpolants[time_constant] = new_interpolant;
}
}
//-----------------------------------------------------------------------------
// getInterpolant()
//-----------------------------------------------------------------------------
F32 LLCriticalDamp::getInterpolant(const F32 time_constant, BOOL use_cache)
{
if (time_constant == 0.f)
{
return 1.f;
}
if (use_cache && sInterpolants.count(time_constant))
{
return sInterpolants[time_constant];
}
F32 interpolant = 1.f - pow(2.f, -sTimeDelta / time_constant);
interpolant = llclamp(interpolant, 0.f, 1.f);
if (use_cache)
{
sInterpolants[time_constant] = interpolant;
}
return interpolant;
}
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