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/**
* @file llcriticaldamp.cpp
* @brief Implementation of the critical damping functionality.
*
* $LicenseInfo:firstyear=2002&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#include "linden_common.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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