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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"
#include <algorithm>
//-----------------------------------------------------------------------------
// static members
//-----------------------------------------------------------------------------
LLFrameTimer LLSmoothInterpolation::sInternalTimer;
std::vector<LLSmoothInterpolation::Interpolant> LLSmoothInterpolation::sInterpolants;
F32 LLSmoothInterpolation::sTimeDelta;
// helper functors
struct LLSmoothInterpolation::CompareTimeConstants
{
bool operator()(const F32& a, const LLSmoothInterpolation::Interpolant& b) const
{
return a < b.mTimeScale;
}
bool operator()(const LLSmoothInterpolation::Interpolant& a, const F32& b) const
{
return a.mTimeScale < b; // bottom of a is higher than bottom of b
}
bool operator()(const LLSmoothInterpolation::Interpolant& a, const LLSmoothInterpolation::Interpolant& b) const
{
return a.mTimeScale < b.mTimeScale; // bottom of a is higher than bottom of b
}
};
//-----------------------------------------------------------------------------
// LLSmoothInterpolation()
//-----------------------------------------------------------------------------
LLSmoothInterpolation::LLSmoothInterpolation()
{
sTimeDelta = 0.f;
}
// static
//-----------------------------------------------------------------------------
// updateInterpolants()
//-----------------------------------------------------------------------------
void LLSmoothInterpolation::updateInterpolants()
{
sTimeDelta = sInternalTimer.getElapsedTimeAndResetF32();
for (S32 i = 0; i < sInterpolants.size(); i++)
{
Interpolant& interp = sInterpolants[i];
interp.mInterpolant = calcInterpolant(interp.mTimeScale);
}
}
//-----------------------------------------------------------------------------
// getInterpolant()
//-----------------------------------------------------------------------------
F32 LLSmoothInterpolation::getInterpolant(LLUnit<F32, LLUnits::Seconds> time_constant, bool use_cache)
{
if (time_constant == 0.f)
{
return 1.f;
}
if (use_cache)
{
interpolant_vec_t::iterator find_it = std::lower_bound(sInterpolants.begin(), sInterpolants.end(), time_constant.value(), CompareTimeConstants());
if (find_it != sInterpolants.end() && find_it->mTimeScale == time_constant)
{
return find_it->mInterpolant;
}
else
{
Interpolant interp;
interp.mTimeScale = time_constant.value();
interp.mInterpolant = calcInterpolant(time_constant.value());
sInterpolants.insert(find_it, interp);
return interp.mInterpolant;
}
}
else
{
return calcInterpolant(time_constant.value());
}
}
//-----------------------------------------------------------------------------
// calcInterpolant()
//-----------------------------------------------------------------------------
F32 LLSmoothInterpolation::calcInterpolant(F32 time_constant)
{
return llclamp(1.f - powf(2.f, -sTimeDelta / time_constant), 0.f, 1.f);
}
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