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/**
* @file llcriticaldamp.cpp
* @brief Implementation of the critical damping functionality.
*
* Copyright (c) 2002-$CurrentYear$, Linden Research, Inc.
* $License$
*/
#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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